Jeep 4.0L Cooling System Re-Engineering

[Mudderoy]

http://muckleroy.com/images/JeepTempGauge1.jpg

About 2 years after I purchased my 1998 Jeep XJ new "literally from the show room floor", it overheated. Since I was on Interstate 10 and going 80 miles an hour at the time, it took me a bit to pull over.

Naturally it wasn't a situation were it was clearly overheating. The temperature gauge read 240, so there was another notch before it was in the RED zone.

As I was exiting I-10 the gauge abruptly dropped from 240 to about 220. The NORMAL running temperature on the gauge is 210 degrees.

I finally pulled over and let the engine cool. I nursed it home, and poured water in it, while the engine was running of course. The factory coolant looked like red clay!

After taking it into the local car repair center, Gary's Tire and Auto of Katy, TX, they found that the plastic fins on the OEM water pump and disintegrated. They also found that the head was warped. So $980 later I got a good running Jeep back.

They replaced the water pump, thermostat, and had the head milled.

About 3 months after the repairs, I started to see a leak. Looking for it I found it was coming from the radiator. It seemed to be near the side, near or on those big end caps.

I went back to Gary's T&A, and they told me it isn't unusual for the radiator to fail after the cooling system has overheated. They told me the end caps were made of PLASTIC (!!!!) and the radiator couldn't be repaired. I could let them replace it, or they could just give me the address of the place where they'd be getting the replacement radiator. I took the later.

The radiator shop removed the radiator from my XJ and put it in the tank of water. Pressurized the radiator with air, and voilÃ* there was the leak, as shown by the stream of air bubbles.

As previously described it wasn't repairable. I purchase a NEW all METAL radiator and had it installed for about $225.

Years past, at least 5 when the water pump went out. This time I replaced it myself. Remember the last time it cost me $900+ ;)

I have replaced the water pump a total of two times! So that means the water pump has been replace 3 times, in 10 years.

The two times I replaced the water pump it was because it was leaking, indicator of a bad seal. The second time because the main bearing failed. This was about a year after I replaced it the first time.

Recently the engine over heated again. Why? Well I think it gets into a cycle of being hot, the water drains to the over flow tank, and a little spills out through the over flow tank over flow tube. Over a period of, I estimate, 3 months the level of the water gets low enough to allow the engine to over heat.

I'll notice the temperature climb to a needles width above the 210 degree mark on the gauge. I knew I needed to add water, but I just keep forgetting about it. On a cold day (for Houston, about 45 degrees) it over heated.

Once I was able to get about 1 gallon of water in it, it was fine, as has been for a couple of weeks now.

Ok enough is enough! I'm fixing this damn cooling system. The cooling system is the WEAKEST part of the Jeep XJ, at least 98 forward.

Step #1: Replace the thermostat with a 180 degree thermostat.

Why? The OEM thermostat is 195 degrees. I don't want the water to have to get to 195 before the thermostat opens. Checking at my local auto parts place for a 180 degree thermostat was pointless. Looking online, also pointless, for the most part.

After finding an article (http://jeephorizons.com/tech/xj_cooling.html) about Jeep XJ over heating I found a link to TBI Specialties Inc. (http://www.turbocity.com/) They had a hi-flow 180 degree thermostat for $14.95 (http://www.turbocity.com/product_info.php?products_id=160). Well it was $9+ for shipping and $5 for handling!!! but I ordered it anyway. :(

Products
------------------------------------------------------
1 x Hi-Flow Thermostat 180º (640-110) = $14.95
------------------------------------------------------
Sub-Total: $14.95
United Parcel Service (1 x 0.11lbs) (Ground): $9.65
Handling Fee: $5.00
Total: $29.60

I'm in a holding pattern right now, waiting for my High Flow Thermostat Housing from hesco (http://hesco.us/).

Item Options Price
High Flow Thermostat Housing #HFTH $27.95
Merchandise Total: $27.95
TX State Tax (0%): $0.00
Shipping to be Determined. <==== Ding ding ding!!!
SubTotal: $27.95

http://hesco.us/img.asp?tn=showandtell_formsRecordsPhotos&fn=LargePhoto&idn=ID&id=54662

I hadn't seen anything about either the shipping cost, or when the part would be shipped, so I sent an e-mail to the address given in the e-mail'd receipt.

I received a reply back in less than 15 minutes with a tracking number (UPS) and the cost of the shipping. $7.83. No $9.65 for shipping and $5 for handling. Just a reasonable charge for the shipping. So if you are keeping track the thermostat cost me $29+ to get it to my house, and the thermostat housing was $34+. Obviously the better buy was with hesco.

I wish I had bought the thermostat from there now too!

The other good news is the part is scheduled to be delivered today!

[Mudderoy]

I received the thermostat housing from hesco yesterday. I started to install all the goodies, but why do today what you can put off until tomorrow?

I highly recommend the hesco thermostat housing. It is very well made and it is a pleasure seeing it on my XJ. I think it was a very good deal, considering the exorbitant amount I paid for the thermostat. (Have I whined enough about the thermostat price yet?)

http://muckleroy.com/images/JeepThermo1.JPG
Here is the old thermostat housing next to the new hesco housing.
As you can see the picture (prior post) from hesco is real.

http://muckleroy.com/images/JeepThermo2.JPG
Old thermostat housing removed.

http://muckleroy.com/images/JeepThermo6.JPG
All the new goodies installed.

Ok the following were installed:

1. High Flow thermostat housing from hesco.
2. Hi-Flow 180 degree thermostat from TBI
3. New temp/transmitter sensor

Heater hoses were NOT replaced because they were about 4 inches too short. They have been returned and credit card credited.

I let the engine get up to running temp. It is about two needles width lower than it was before. So guessing it would be about 206 degrees instead of the normal 210.

I drove to Wal-Mart and back, actually made one stop to return the heater hoses. The temp stayed at about 206.

I left the engine running while I put some RainX on the windshield. That took maybe 10 minutes. I checked the temp gauge again. About 211.

Maybe I don't have the cooling system full of coolant yet, but this is what I expected. I didn't think the thermostat would do anything to make the engine run cooler, only that it would allow the equipment to cool the water before it said 210 on the gauge.

I also found that the lower bolt on the thermostat housing was very lose.

Anyway tomorrow is a work day so the stop and go traffic on I-10 will be a very good test.

[Mudderoy]

As promised here are the temperature readings while I was coming home from work today. This first picture was taken after the engine had been running for about 20 minutes. I had traveled between 40 and 70 miles an hour by the time I reached I-10.

I'm sorry for the quality of the pictures, but I was driving, and the 4x4 bounces. :D

http://muckleroy.com/images/JeepThermo7.JPG
Remember the speedo is off because of the larger tires. The speed here would have been about 68 or 69 mph. You can see the temp is about 206 degrees(??)

http://muckleroy.com/images/JeepThermo8.JPG
This is about 2 miles down the road, and my speed had increased to about 84 mph for a couple of minutes. Here I am going about 77 mph. This is the reading the gauge would normally be at after the engine was fully warmed up. Before going 80+ mph the gauge would read 211 to 212 degrees.

Bottom line?

It looks like something is a little cooler, or maybe the new temperature sensor is just reading lower. I don't think it is the sensor, I think the additional flow, and the thermostat opening at 180 degrees instead of 195 is allowing the water to stay cooler longer.

This ISN'T going to make the engine run cooler! I'll need an electric fan, and/or a 3 core radiator to accomplish that, but those changes are coming soon.

Stay tuned.

You may be wondering what the heck the speed limit is on I-10, 106 mph. I thought I was going to be run over!

[Mudderoy]

Update -

As i expected the engine cooling system is running a few degrees cooler. I suspect this is due, again, to the thermostat opening at a lower temperature.

The temperature does rise as engine use or load increases. Sitting still seems to cool faster and return to slightly below the normal 210 degrees I am so accustom to seeing over the last 10 years.

It took me less than an hour and about $70 to make this change. A electric fan would have been around $125 and should take about as much time to replace.

I believe the electric fan would have made a difference on the overall cooling of the engine, however having a good thermostat and the additional flow of water in both the thermostat and high flow housing is worth having, and may save me in the future.

This was the cheapest of the three things I want to accomplish on the re-engineering of the XJ's engine cooling system.

[TeXJ]

XJs are known for overheating lol

[Mudderoy]

Well I finally did what I wanted to do and got a 3 core radiator. After some research I went with radiatorbarn.com (I know the name sounds ominous).
They were great! No problems and I had my new radiator fast, like 3 days later.

http://muckleroy.com/images/jeep_temp3.jpg

Update: The price has changed, and availability may be an issue now.

http://muckleroy.com/images/Jeep_radiator1.jpg
After receiving the radiator I called radiatorbarn because of this BENT piece. They said it was normal (because of the packing) just straighten it out and it would be fine. I did and it was. :D

I got the radiator installed and temps were better. About four months later (still very hot outside) I noticed this!
http://muckleroy.com/images/Jeep_radiator2.jpg

I was only able to see this level of detail after removing the electric fan (on the driver's side)

After removing the radiator I was better able to tell what was going on. The electric fan housing had worn a hole in one of the fins. You can see the line here.

http://muckleroy.com/images/Jeep_radiator3.jpg

This was due to the added width of the radiator (3 core instead of 2), or the bracket that holds the electric fan at the bottom of the radiator was put too close to the radiator allowing the electric fan frame (or housing) to make contact with the fins.

Radiatorbarn didn't hesitate to send me a new radiator and pay to ship the old one back. It would have been really simple to repair this leak but Radiatorbarn went the extra mile and just took care of it!

http://muckleroy.com/images/jeep_temp1.jpg
Love this little gadget! Just point it at the thermostat housing.

What's next? Replacement of the mechanical fan with an electric fan and supersizing my transmission cooler!!!

[TeXJ]

i got my 3core radiator from them too. great people to deal with!

[OMOC]

i found a big diffrents in temp when i put a tranny cooler in and moved away from the in tank unit. my xj now runs at about 180*f all day long, even out on the trail. also im still useing the mechanical fan have had no issues with it

[Mudderoy]

i found a big diffrents in temp when i put a tranny cooler in and moved away from the in tank unit. my xj now runs at about 180*f all day long, even out on the trail. also im still useing the mechanical fan have had no issues with it

That gives me hope. I have the factory transmission cooler which I am sure helps, but it is really small compared to the aftermarket ones.

[kryptonitexj]

I been through this same situation. Here was my plan of attack. Replaced Mechanical Fan with a hayden 12 e-fan and Adjustable e-thermostat. Installed a new 3 core "Heat buster" Aluminum radiator from HI-LO. Worked well for a while. Still had heating problems. Tried water wetter. No go. Finaly Removed E-fan and Reinstalled Mechanical fan BUT with a ZJ 4.0 "Max-Cool" fan clutch From Napa. Haven't had a proble since.:D

[Mudderoy]

Thanks, I'll have to look into that.

Back in my small block chevy days the first thing we did was trash that clutch and fan and replace it with a spacer and fixed fan.

[Bighorncrag]

I've also started the re-engineering of the cooling system. Another piece to consider but rather spendy is the HESCO's high flow water pump (http://www.hesco.us/shop.asp?action=details&inventoryID=45086&catId=7967). I'm not as far along in my conversion so I'm not ready to pay $170+ for a water pump.

[Mudderoy]

I've also started the re-engineering of the cooling system. Another piece to consider but rather spendy is the HESCO's high flow water pump (http://www.hesco.us/shop.asp?action=details&inventoryID=45086&catId=7967). I'm not as far along in my conversion so I'm not ready to pay $170+ for a water pump.

Yes, I have looked at that. I want to get one, but like you the price is a bit high. I have the hesco high flow thermostat housing and thermostat now.

I'll be adding a B&M transmission cooler this weekend in an attempt to lower the transmission temps. I am thinking that this may be adding additional heat to the cooling system. With the 3 core in place and air temps above 90, my coolant temp hits 215 to 220 while at 70 mph. I stop, or slow to 30 to 40 mph and the temp drops to 210. So it appears that the cooling system is working very well, it just can't handle keeping it that cool at highway speeds. Part of the problem (I am sure) is my 4.56:1 gears. I run about 2800 rpm in over drive at 70 mph.

Sorry if some of this is a repeat from this thread, I didn't go back and read it all before this post.

[Jeepster19]

I recently did a upgrade on my 98 xj's cooling system.Upgrade included a 3 row radiator,hesco water pump,high-flow thermostat housing with high-flow 195 thermostat,hayden fan clutch,and all new hoses.My temp is around 195-200 all day long.I realize I spent a some cash on it but it was well worth it!!!I hope this helps!Oh yeah,one more thing.On a computer controlled vehicle it's always best to stick with the factory thermostat,195 in our case.Switching to a lower one will tell the computer the engine is not warm and will dump more fuel which will decrease mileage.This info was provide by a good friend who is ase certified,besides he works on my xj and I trust him.He's never steered me wrong yet.

[Mudderoy]

I recently did a upgrade on my 98 xj's cooling system.Upgrade included a 3 row radiator,hesco water pump,high-flow thermostat housing with high-flow 195 thermostat,hayden fan clutch,and all new hoses.My temp is around 195-200 all day long.I realize I spent a some cash on it but it was well worth it!!!I hope this helps!Oh yeah,one more thing.On a computer controlled vehicle it's always best to stick with the factory thermostat,195 in our case.Switching to a lower one will tell the computer the engine is not warm and will dump more fuel which will decrease mileage.This info was provide by a good friend who is ase certified,besides he works on my xj and I trust him.He's never steered me wrong yet.

I don't think the lower degree thermostat makes any difference in the mpg. If it does it's less than 1 mpg. I've read the same from NAXJA folks. If the cooling system isn't capable of keeping the coolant temp down to 160 or 180 then the only time the gas mileage MAY be effected is when the coolant is warming up to the 200's. With my 180 degree thermostat I only see lower than 210 on cold days, otherwise it is up to 210 within 5 to 10 mintues.

I've increased my gas mileage from 10.5 to 13.0. I am hopeful that this tank of gas will see a modest increase. I am further with less fuel. I am nearing 3/4 a tank and 100 miles traveled. I was seeing 130 to 150 at 1/2 of a tank. What did I change? The CPS!!! My occasional miss is gone, and gas mileage SEEMS to be up.

[BlueXJ]

Been following this thread closely. I have the high flow pump and housing from HESCO. Bennie is quite helpful. I have a 2 row but all metal radiator and mine is a Renix closed system so I dumped the plastic tank for an aluminum tank. I want to do what Mudd was talking about in his SBC days with a fan clutch eliminator but it would need to be machined and I have no access to a lathe. Do you know of another that is commercially available? Mine does as yours does. Run around town in stop & go traffic and it stays right at 210 but at 75mph on the highway it goes to a needles width or two past the 210* mark. Slow to 60mph and it drops back to 210* again.
Blue

[Jeepster19]

I don't think the lower degree thermostat makes any difference in the mpg. If it does it's less than 1 mpg. I've read the same from NAXJA folks. If the cooling system isn't capable of keeping the coolant temp down to 160 or 180 then the only time the gas mileage MAY be effected is when the coolant is warming up to the 200's. With my 180 degree thermostat I only see lower than 210 on cold days, otherwise it is up to 210 within 5 to 10 mintues.

I've increased my gas mileage from 10.5 to 13.0. I am hopeful that this tank of gas will see a modest increase. I am further with less fuel. I am nearing 3/4 a tank and 100 miles traveled. I was seeing 130 to 150 at 1/2 of a tank. What did I change? The CPS!!! My occasional miss is gone, and gas mileage SEEMS to be up.
Good luck!!!Give us a update when you get one.

[Bighorncrag]

With the talk of temps running up to what sounds to be the 215 to 230 range, has anyone had the clutch fan engage? And at what temp? I've never had mine engage (electric runs frequently), to my own impatience. I was on a road trip across the state last summer and bought and installed a brand new clutch fan while on the road. No change in operation and cooling, the old one was just fine. Being a shade tree mechanic, I rely on my local expert who says the 4.0L clutch fan has a pretty high temp engagement. Here I was used to my old 79 chev 1/2T 4x and 90 Suburban 454. The clutch fan would engage on those rigs even though the needle hadn't moved on the gauge.:coffee:

[Melissa]

What I am not understanding is why some of your temps rise when going faster down the highway??, mine runs the coolest at those speeds, a needle width above the center mark between 100 and 210. It's when I pull a hill, or get into stop and go traffic that mine gets way to hot, other wise I can run all day and never hit the 210 mark.

Yes, I'm still driving my jeep, even with a unknown problem.

[Mudderoy]

Yeah I know. I don't ever recall having a vehicle do what mine is doing now. Basically I am generating more heat than the system can keep cooled to 210 degrees. The coolest it can keep it is the 215-220 I was talking about.

As soon as I slow down the heat generation is less and my cooling system rapidly cools close to the 210.

So either I am missing something (collapsed hose, bad water pump) or I need to increase my cooling. I'm adding a tranny cooler to see if this is where the additional cooling needs to occur.

Oh, and I need to mention I am sure that running the A/C and making the condenser very hot has a lot to do with this.

[Melissa]

I'm real interested in knowing what the outcome is after you get your tranny cooler in.

[Baddmove]

Hey Mudderoy, i just read this tech article because i was going to put in a lower temp thermostat also, check it out.. http://www.olypen.com/craigh/cooling.htm

There is a popular misconception that installing a lower temp thermostat will help an engine run cooler, and/or solve an overheating problem. This is simply not true. The engine will still operate at the same temp regardless of what thermostat you install. The only function of the thermostat is to determine at what temperature the coolant starts to circulate through the system. It does not determine how hot the engine can get after it opens. That is a function of the system's capacity and radiator's ability to exchange or dissipate heat. Once the thermostat opens (whether it's at 195º, 180º, or 160º) the coolant starts to flow and the engine will eventually heat the system to the same temperature, it will just take a little longer with a lower temp thermostat opening sooner, and this is not what you want. Since the internal combustion engine is less efficient at sub-normal operating temps, the thermostat is designed to get the engine temperature up to normal as soon as possible. By installing a low temp thermostat, you are probably doing more harm than good.

[Mudderoy]

Hey Mudderoy, i just read this tech article because i was going to put in a lower temp thermostat also, check it out.. http://www.olypen.com/craigh/cooling.htm

There is a popular misconception that installing a lower temp thermostat will help an engine run cooler, and/or solve an overheating problem. This is simply not true. The engine will still operate at the same temp regardless of what thermostat you install. The only function of the thermostat is to determine at what temperature the coolant starts to circulate through the system. It does not determine how hot the engine can get after it opens. That is a function of the system's capacity and radiator's ability to exchange or dissipate heat. Once the thermostat opens (whether it's at 195º, 180º, or 160º) the coolant starts to flow and the engine will eventually heat the system to the same temperature, it will just take a little longer with a lower temp thermostat opening sooner, and this is not what you want. Since the internal combustion engine is less efficient at sub-normal operating temps, the thermostat is designed to get the engine temperature up to normal as soon as possible. By installing a low temp thermostat, you are probably doing more harm than good.

Yep I agree. Bad thing about posts, they are hard to find, or hard to remember. I never updated this one.

I went to hi-flow everything (thermostat, thermostat housing, and water pump). Thermostat is 195 because that's what the computer likes.

I think a 180 or 160 thermostat will help the cooling system run cooler but that's only in the short term. As you drive it's still going to heat up to what ever balance it finds between the heat being generated and the ability of the cooling system to get rid of that heat.

My eventual solution to the running hot on the highway, or heat creep, was a stock type radiator. Aluminum/plastic. Mine came with a 2 row, but I have a single "large" row in it now. I will be going back to a 2 row, and hopefully I can find a good all aluminum, because I still don't like the plastic ends.

[Carves]

Yep I agree. Bad thing about posts, they are hard to find, or hard to remember. I never updated this one.


slacko .. :poke: .. :D

... maybe you could merge it with your other one ?? .. It may be a little disjointed, but all the info would be in the one thread.


Just some thoughts & info .... using the quotes as start points.



I went to hi-flow everything (thermostat, thermostat housing, and water pump). Thermostat is 195 because that's what the computer likes.


Speeding up the flow i.e. increasing the number of passes the eth-gly does through the rad ... does "technically" assist with cooling.
..... but the more thrashing the waterpump does ... the more likely its creating, corrosion causing and hot spot forming, bubbles.

I'm presuming that since the northern hemisphere has been using 50/50 eth-gly/water for so long ... that the vehicle designers would already be fitting pumps - best suited for the task ??

Faster flow works well in cold room scenarios with fixed piping sizes .... but I have my doubts, as to the long term benefits in a vehicle ... given the twists, turns and varied opening sizes in an engine block & head ... but thats just my thoughts .. ;)

Granted that the 195* t'stat may provide that "optimum" operating temp ... Its not really a great operating temp, when the provided cooling system ... and quite a number of ebay marvel, "cooling fix" add-ons ... are generally, unable to ensure that , that operating temp is maintained.

FWIW & IMHO .... its a lot better to be running at 185* in the short term ... and running at 200* underload ... rather than starting at 200* and then watching the temp gauge dancing around under load.

....Underload being things like offroading, stuck in traffic, highway & towing ... and maybe lap 26 of the mall carpark, etc., ... :D

Ultimately of course ... the ideal situation is to have a constant, stable, 200* or thereabouts, running temp.


It seems that in reality ... the computer likes whatever temp the engine runs at below 218* ... except this one ...

Code 17 ... P0125 ... Closed Loop Temp Not Reached.
Engine does not reach 20°F within 5 minutes - with a vehicle speed signal.

Be aware that the above temp is not THE, Closed Loop temp as such ... but a required temp and driving situation, once the Closed Loop timer activation has occurred within minutes of startup ... which is generally by about the coincidental time, the coolant temp has reached 65*

The computer especially likes temps in the 160*-170* range as thats about when the computer auto clears non important CELs & DTCs etc.

If any other Emission DTC is set (not an OBDII Monitor), a Good Trip is considered to be when the Oxygen Sensor Monitor and Catalyst Monitor have been completed; or 2 Minutes of engine run time if the Oxygen Sensor Monitor or Catalyst Monitor have been stopped from running.

It can take up to 2 Failures in a row to turn on the MIL. After the MIL is ON, it takes 3 Good Trips to turn the MIL OFF. After the MIL is OFF, the PCM
will self-erase the DTC after 40 Warm-up cycles. A Warm-up cycle is counted when the ECT (Engine Coolant Temperature Sensor) has crossed 160°F and
has risen by at least 40°F since the engine has been started.

Nothing there about needing a 195* t'stat to achieve a computer recognised warmup temp .... Just that the coolant sensor needs to see 160* or above ....
...... Which a 160* t'stat will provide. ;)

I dont think, the computer likes temps over 218* ... coz thats when it turns on the little, "OMFG I'm overheating" 12v aux fan .. ;) .. :)

Now of course ... all the above doesnt mean 160*/180* should be a target temp for the XJ ... just that a bit less than the presumed "best" temp of 210* ... isnt as crucial as folklore would suggest.

Personally .... Im happy with 190*-195* .... and if we are all very lucky ... some dedicated, knowledgable, XJ dabbler like Cheromaniac or someone - might be able to chime in with some of the the PCMs actual, preset, air/fuel ratios at various coolant temps, above and below the computer recognised "warmed" temp of 160*/170*.



I think a 180 or 160 thermostat will help the cooling system run cooler but that's only in the short term. As you drive it's still going to heat up to what ever balance it finds between the heat being generated and the ability of the cooling system to get rid of that heat.


... and theres the crux of the whole "overheating XJ" issue.

The XJs inadequate cooling system as mentioned in that writeup Baddmove linked to.

4.0l XJs dont nescessarily "like" to run hot .... as internet myth would suggest ... but rather - they run hot coz of the piddly little cooling system ... and whatever loads owners place on them, according to driving scenarios and drivetrain mods.

oooops ... can I say "piddly" on a family forum ... :D


X 2 on not making things better - just by jamming in 160*/180* t'stats ... even tho the parts books lists a 180* as an option for the XJ.

A small gain might be had in the short term ... but on its own ... its not a cooling "fix" in an XJ.

If the coolant doesnt shed enough heat in the rad ... the coolant will go back to the engine too hot ... to which the engine adds its operating heat ... providing the result at the thermostat housing.

If you're lucky ... the hotter temp, beyond the control of the t'stat ... will be a happy balance ... but in the case of the XJ ... extra engine load can quickly upset that delicate balance.

Ideally imho ... the rad should "overcool" ... for lack of a better word ... and the t'stat, (a quality one) ... will meter the flow, maintaining a temp slightly over its rated temp.

Which is a lot better than the t'stat just opening at its rated temp and a constant flow of even hotter coolant occurring ... and the max temp being determined by the use of the loud pedal, dodgy fans, incorrect/stale coolant mixes, climate ambients ... or whatever.



My eventual solution to the running hot on the highway, or heat creep, was a stock type radiator. Aluminum/plastic. Mine came with a 2 row, but I have a single "large" row in it now. I will be going back to a 2 row, and hopefully I can find a good all aluminum, because I still don't like the plastic ends.

X 2 on an all metal rad ... Im thinking that cheapness of production, is leading to, way under quality plastics and seals being used ... compared to the quality of the factory original, 1row alloy & 2row alloy & copper rads.

..... and cheapness of production is the whole reason alloy rads came about in the first place anyways ;)

Alloy or copper is not really the issue in getting a good rad ... its more to do with the core tube sizes and fin spacing.

The bestest ever, most expensive, alloy ... or copper ... rad ... will be a dud ... if the tube sizes are:
- Too small/too large a diameter, or
- Too many -blocking airflow as some find with 3row units - and some 2row, going by Mudderoys info/data, or if
- The fin spacing is not conducive to good airflow/heat shedding ability.



.......................... I rely on my local expert who says the 4.0L clutch fan has a pretty high temp engagement.


This is a good/interesting, point ... and additionally, its only a basic, light duty fanclutch.

Would be interesting to know whether the NAPA ZJ HD fanclutch which seems to be successful - has a lower operating temp in addition to its heavier clutch action.

My limited temp testing of the USMW branded, "stock" style replacement I'm using ... suggests its activating a little sooner.

Factory fanclutch testing specs ...
Temps are air temps ... not coolant temps.

Fan drive engagement should have started to occur at between 74° to 82° C (165° to 180° F).
Engagement is distinguishable by a definite increase in fan flow noise (roaring).

Fan drive disengagement should have started to occur at between 57° to 79° C (135° to 175° F).
A definite decrease of fan flow noise (roaring) should be noticed.

.... and given the air temps the spring sensor on the fanclutch needs to "see" ...... just how critical is the size/location of vent holes in hoods ... or that annoying plastic skirt under the engine that stops one getting at components easily ... or the front bumper airdam/front bashplate ... or the missing fanshroud ... or the amount of extra underflow air caused by major lift heights ... or even the amount of mud, caked on the front of the fan ????? ... ;)


... apologies for the long winded post ..:o

You'se can all click on another thread when you wake up ... :D

[4.3LXJ]

As for that fan clutch, I maintain old school is better. Direct drive unless you live in the Arctic, north or south. Air flow is always good anywhere else.

[Carves]

As for that fan clutch, I maintain old school is better. Direct drive unless you live in the Arctic, north or south. Air flow is always good anywhere else.


Yep, a simple reliable system. :thumbsup:

The only reason it wont work ... is if the belt breaks.

"New School" of course dictates ... fancy fan types that have any number of reasons for not working properly ... and all for a teaspoon worth of petrol saved, an imagined ability to wheelstand at the race track, and the protection of our eardrums coz the roaring of a fan moving air is "annoying" .. :rolleyes:

One really has to wonder whether the benefits of the HP/fuel economy gains ... over the life of the vehicle .... are really worth the servicing costs to maintain ... or even "upgrade" ... the system during that time. ;)


I noticed an earlier post asking about fan spacers ... The Derale catalogue lists a selection that might be useful ... for anybody with a preference for a direct drive fan mod.

[XJ4IV]

do what I did... stop driving it on the roads... its that damn blacktop LOL
actually Im glad I looked over this thread... I laughed a bit when I started reading all this caus I joined about a year and a half ago and I was like "havent we heard all this before?"
then I looked at the dates DUH but my cooling system is doing OK I suppose, I recently installed a dual E-fan setup and currently I cannot recall if I have a thermostat in there LOL if I do its a 195* and I also have a 3row from rad barn.com and JUST like tony I got mine three days after purchase and JUST like tony... the opening was jacked a little bit too , hate to see it happen but glad to see it IS common I think the BEST thing I will take from this thread is that folks are bypassing the trans cooler in the radiator and installing an auxillary cooler in a different location!... I think with this VERY hot summer coming up I will be doing that REALLY soon! hopefully before my birthday run!

[07Negative]

There's always Hesco for Therm housing, T-stats, and water pumps. They aren't even all that expensive.
I have that same radiator. It's a piece of shit. It took 3 rads before I got one that wasn't beat to hell. One thing you'll probably notice with that rad is that the rad. cap will squeak against the metal piece that holds the rad. in place. I used a dremel to cut away so it wouldn't. Drove me flippin nuts. If you've got the money. The Griffin rad. is worth the money and it's made in USA not Taiwan.
The fans from Dirt Bound are dope. They work really well.

[Mudderoy]

Wow the price has really come down on the water pump, it was up around $300...

Now $169.95

http://www.hesco.us/img.asp?tn=showandtell_formsRecordsPhotos&fn=LargePhoto&idn=ID&id=55182


:link: (http://www.hesco.us/shop.asp?action=details&inventoryID=45086&catId=7967)

[07Negative]

Its not bad I don't think. I bought all their cooling stuff minus radiator. I got the radiatorbarn junk when I very well knew i should have got the Griffin. So far so good though.

[4.3LXJ]

Hey DeeJay, the Griffin has a good rep and works really well, but I found out the hard way they don't last. They epoxy the tubes to the header instead of brazing them. That epoxy fails after a couple of years and is almost unfixable. I am working on fixing mine, but it still will only last a couple of years before the epoxy lets go again. Other brands braze their tubes and is becoming an industry standard.

[willtodo]

What is the CPS,,, if gettin a new one will give me 2 or 3 mpg ill doit

[4.3LXJ]

The CPS is the crank position sensor and is located on the outside of the upper driver side bell housing. It senses when the crank is top dead center so it can signal the injectors to squirt. They usually work or don't. I am not sure how that would affect milage unless a bad signal would keep the injectors from working properly all the time. But that would be a very jerky ride.

[Mudderoy]

Let me set the record straight here. I have not been pleased with the cooling system performance of the Jeep 4.0L Cherokee. Even before the lift and tires. Now with that said I did find that I caused a problem by using the wrong radiator. I didn't research it enough to learn that the factory radiator was a 2 row aluminum/plastic. I assumed that as long as it was all metal and had more rows it should perform better than the stock radiator. It didn't.

I have made several modifications to the cooling system, and even exhausting the heat from under the hood. It is quite possible that I have made several improvements, however it's really hard to be sure because the radiator was the last thing I replaced (twice) in the process.

I would recommend a good clean coolant system, and a new factory type radiator, which includes row size diameter before going hog wild replacing things. :thumbsup:

[Cheromaniac]

Personally .... Im happy with 190*-195* .... and if we are all very lucky ... some dedicated, knowledgable, XJ dabbler like Cheromaniac or someone - might be able to chime in with some of the the PCMs actual, preset, air/fuel ratios at various coolant temps, above and below the computer recognised "warmed" temp of 160*/170*.

Well I haven't a clue what the A/F ratios are at various coolant temps. except that I know the engine runs rich with more timing advance when the engine's cold. At 160*F the PCM has already gone into closed loop so there's one myth you can kick into touch.
If you install a 160* t'stat, the engine will simply take longer to warm up and run in rich warm-up mode for a longer time, so gas mileage will go down especially in the winter. In the winter months when you need the heater to prevent your balls from freezing up, it'll be practically useless 'cause the air that'll blow out of the vents will at best be lukewarm. If you live near the Equator where it's warm year round, you could run a 160* t'stat or even no t'stat and not have any problem 'cause the engine will still warm up quickly, and the final temp. that it reaches will depend on how well the cooling system works (almost certainly higher than 160*).
I live in a hot desert climate so a 180* t'stat works fine for me. As long as the outside temp. is below 90*F my gauge will stay at 180* when I'm cruising on the highway. If it's 120*F outside, the gauge hovers around 210* and it'll go slightly higher if I have the AC on (which is inevitable if it's hot enough outside to fry an egg on the hood). In the cooler months the heater works well enough for me 'cause I don't need it to be roasting hot. If you want hot air for those cold winter days, use a 195* t'stat or higher.
Jeep obviously designed the 4.0 to run between 195* (the t'stat opening temp.) and 218* (the electric fan on temp.) because that's the most thermodynamically efficient range for best gas mileage and emissions. If you drive a lot in extreme heat (as I do) or you subject the engine to high loads (as you do when offroading especially in sand dunes), it wouldn't come as a surprise to see the temp. gauge occasionally go above 218* if the cooling system is stock. That's why many of us modify the system but many times it's trial and error. Why?
Let's get one thing out of the way. If your engine tends to overheat, a lower temp. t'stat will do diddly squat. I've also observed that the factory clutch fan is practically useless. If it was any good, you wouldn't see the temp. gauge rise steadily to 218* when idling and you wouldn't need an auxiliary electric fan to cool the engine down again. FWIW you're better off running two electric fans in tandem and I've been doing that for 11 years. If you do a lot of offroading, get the highest cfm capacity electric fans you can fit and since they're going to suck a lot of power from the battery, consider upgrading to a higher output alternator at the same time. If you have an auto tranny, an auxiliary cooler is essential.
The stock water pump is adequate except under high load conditions, where a high-flow pump will circulate coolant faster and dissipate the heat. If you're scaling a long uphill incline, the temp. gauge won't rise as fast if you have a high-flow pump. Ideally the pump impeller should have a plate on the back to prevent cavitation at higher rpm.
The stock 2-row radiator is adequate even for a mild 4.6 stroker like mine except in extreme conditions, and that of course only applies if it's fairly new. If it's as old as the Jeep, the chances are that its internals will be clogged up with limescale/rust/dirt and it'll barely have enough capacity to cool a sausage. That's a good excuse to upgrade to a thicker radiator than stock but don't get a 3-row version 'cause the tubes will be smaller. Get a 2-row 'cause that'll have bigger tubes and dissipate more heat. If you choose an aluminium rad, use coolant meant for aluminium engines even though your engine's cast iron. Otherwise you're likely to get brown slime build-up inside the rad, small leaks might appear after a few months, and you'll be cursing the day you spent $300+ to buy the damn thing. You'll probably also curse the manufacturer for producing an expensive, useless POS.
Finally I'll touch on ported t'stat housings. If you're running a t'stat, the t'stat will be the flow-limiting factor in the cooling system and a ported housing will do absolutely diddly squat except look pretty and lighten your wallet (much like a wife or GF really ;)). Even if you don't run a t'stat, it's still a waste of money anyway unless you like to pimp your engine with a bit of bling.

[Cheromaniac]

I forgot to mention hood vents. Yes, they're a good idea 'cause releasing all that pressurized hot air from the engine compartment will allow more cooler air to flow through the radiator. That is, provided you position the hood vents correctly.
The back of the hood is definitely NOT the place to put them 'cause that's a positive pressure area and air will get blown back under the hood instead of being sucked out. The best place is at the front right above the space between the radiator and the engine. Negative pressure above the hood will draw hot air out from underneath and if it rains while the Jeep is at a standstill (or you wash it), the water will drain onto the ground and not get into any electrics. The hood vents on a Mitsubishi Evo and a Shelby GT500 are good examples of how it should be done.

[4.3LXJ]

I have to agree with that one. Most people go for the back because they think the air will get let out the back. But only when parked or very low speed.

[bluedragon436]

I'm just going to take my hood off... damn the man!! LOL... I'm sure the DE/MD cops will love me even more than they already do with my tires sticking out of the flares.. LOL

[nickxj94]

I forgot to mention hood vents. Yes, they're a good idea 'cause releasing all that pressurized hot air from the engine compartment will allow more cooler air to flow through the radiator. That is, provided you position the hood vents correctly.
The back of the hood is definitely NOT the place to put them 'cause that's a positive pressure area and air will get blown back under the hood instead of being sucked out. The best place is at the front right above the space between the radiator and the engine. Negative pressure above the hood will draw hot air out from underneath and if it rains while the Jeep is at a standstill (or you wash it), the water will drain onto the ground and not get into any electrics. The hood vents on a Mitsubishi Evo and a Shelby GT500 are good examples of how it should be done.

Something like mine they work really well on the heat escaping http://img.tapatalk.com/18f8c232-184a-199d.jpgand I have lift my Hood a inch at the hinges for more cool air to get in here in the Arkansas humidity and 92 temp mine don't get over 210 unless siting at McDonald's then the fan kicks on and keeps it cool

[Carves]

I have to agree with that one. Most people go for the back because they think the air will get let out the back. But only when parked or very low speed.


X 2

Was having a chuckle at the cute "hood vents" on a little mercedes in the driveway the other day.

... and even tho the "vents" were mounted in the rear, hood corners - which can be an acceptable location for low & hi speed driving .......


http://i1143.photobucket.com/albums/n629/carves-oz/Vehicle%20Bits/Cooling%20Bits/Merc01b.jpg


........ I scratched my head for a bit and came to the conclusion - that even tho the openings were away from the center, highest pressure, a bit ... the hood angle/incline was still too great for satisfactory venting .... and they would work better for induction purposes.








When I opened it up .......... I found the germans had decided the same thing .. ;) .. :D


http://i1143.photobucket.com/albums/n629/carves-oz/Vehicle%20Bits/Cooling%20Bits/Merc02b.jpg

[XJ408]

I'm having an cooling issue with my 1994 grand Cherokee. There's a leak coming behind water pump. That is my assumption.

Is there any other ideas might where the leak is coming from?

[Cheromaniac]

I'm having an cooling issue with my 1994 grand Cherokee. There's a leak coming behind water pump.

The coolant's probably leaking from the water pump weep hole and that happens when the pump shaft bearings wear out and the seal is broken. The only other possible source in that area is the thermostat housing and any hose that's attached to it.
The best way to find out where the leak is coming from is to run the engine up to operating temp. and then switch it off. Immediately after you shut the engine off any coolant leak will temporarily increase and it'll be easier to spot the source.

[Mudderoy]

Okay so first real test of the cooling system. Now I don't have the high flow water pump, thermostat or thermostat housing on the 4.0l right now. Plus I have a stock hood, so the cowl induction scoop isn't helping. I guess it's really just a test of the single row aluminum/plastic radiator.

Yesterday's drive time air temp was 101 degrees. I drove about 5 miles before getting to 210. Then another 5 before it started creeping over 210. By the time I got home (about 20 miles total) I was nearing the next hash after 210.

The motor was running fine, and it didn't smell hot. Also when I say nearing truth be told, it was maybe slightly past the mid point of the two hashes.

After I got home I checked to see if the electric fan was running, it was. Then I cut the engine off and checked how tight the HD GC fan clutch was. Very tight!

This morning I checked the coolant level in the radiator, it was filled to the top and clear. The overflow bottle was at the proper cold level.

So I think the small head leak (that the chemical test revealed months ago) and high air temps are just overwhelming the single core radiator.

I'm tempted to put the other hood on (scoop) to see what difference it would make, if any.

[Cheromaniac]

Sounds like your temps. are OK and from what you've described, if you do have a head leak it's so tiny not to be a concern at this stage. All seems to be well as far as I can see though it wouldn't hurt to upgrade the radiator to give you an extra margin of safety from overheating.
Just check the coolant level in the overflow bottle at least once/week and monitor for any signs of coolant loss that might be an early sign of the head cracking.

[Mudderoy]

Sounds like your temps. are OK and from what you've described, if you do have a head leak it's so tiny not to be a concern at this stage. All seems to be well as far as I can see though it wouldn't hurt to upgrade the radiator to give you an extra margin of safety from overheating.
Just check the coolant level in the overflow bottle at least once/week and monitor for any signs of coolant loss that might be an early sign of the head cracking.

I've been putting it off, but yeah it came with a dual row and that's what I need to put back in it. I just need to research tube diameters and make sure I get something that is really bigger and not just two rows that are equal to the one row I have now.

If anyone has tube diameters of the stock dual row radiator I'd appreciate the info.

[Carves]

I've been putting it off, but yeah it came with a dual row and that's what I need to put back in it. I just need to research tube diameters and make sure I get something that is really bigger and not just two rows that are equal to the one row I have now.

If anyone has tube diameters of the stock dual row radiator I'd appreciate the info.

E-Mail the supplier of the radiator and request the specs of the core they used.

If you got it off a reseller e.g. NAPA or whatever ... they probably wont have a clue ... and you will have to head further up the supply chain for info.

Most places down here are happy to share info ... but I still had to ring head office to get specifics on the copper XJ rad', this mob supply .... http://www.adrad.com.au/manufacturing/

[Mudderoy]

Matt wanted me to hook up the OBDII today and see just how hot the cooling system was getting. Here's what I found.

230.0 degrees, at times.

This occurred after going 3/4 of the trip home, which is about 20 miles total. Air temps were in the 99 to 102 degree range.

Since I had it on my list of things I was monitoring I can tell you my average speed was about 30 mph. Funny how this back road trek gets me home 5 to 10 minutes quicker than driving 80 mph on the freeways.

I was running about 226 and it would drop to 224 after driving about a mile at 50 mph. It would spike to 230 if I used a lot of throttle, then slowly come back down as I drove.

After I got home I sat in the drive way at idle. Just idle, no revving. It took about 5 minutes for it to come down from 230, it jumped shortly after pulling into the driveway, to 228, 227, 226, 224. Then seemed to level out.

I turned off the A/C and it dropped to 217 after another few minutes. I heard the electric fan switch off. After that it climbed back up to 222, so I decided to switch on the electric fan over ride switch.

After another 5 minutes with the electric fan on and A/C off it was back to 210 degrees.

230 degrees is about 1/2 way between the two hash marks, with the left hash mark being labeled 210.

[Mudderoy]

E-Mail the supplier of the radiator and request the specs of the core they used.

If you got it off a reseller e.g. NAPA or whatever ... they probably wont have a clue ... and you will have to head further up the supply chain for info.

Most places down here are happy to share info ... but I still had to ring head office to get specifics on the copper XJ rad', this mob supply .... http://www.adrad.com.au/manufacturing/

I know (or knew) the tube diameter of the radiator I have now. What I would like to know is the tube diameter of the factory two core that my XJ came with. Then I would know what to look for.

[Carves]

ooops .... you meant the original stock rad ... :D

I regret not pulling mine apart before scrapping it too.

Any laying around up at ... Matts ??, shed ... that he wouldnt miss ... or notice the end cut off ;) .. ;) .. :D

[Mudderoy]

ooops .... you meant the original stock rad ... :D

I regret not pulling mine apart before scrapping it too.

Any laying around up at ... Matts ??, shed ... that he wouldnt miss ... or notice the end cut off ;) .. ;) .. :D

I didn't think of that. In the hay days of the internet who would think of picking up something, physically, and measuring it! What a concept!

[4.3LXJ]

Tony, you can get the OEM core specs from a radiator shop that rebuilds and recores. If the have to match the original tanks, like we did with the HUM WEE radiator, that info has to be available from the core supplier at a minimum.

[Mudderoy]

Well I monitored the temp today. It took 5 miles at an average speed of 27 mph, 98 degree air temp, to get to 210. At 7 miles it was up to 214.

About 12 miles I was seeing 232, and it would drop to 226 after driving a mile at 55 mph.

As I got less than a mile from the house the temp increased to 240!!!!! I drove about another 100 yards to the light, and the temp started dropping rapidly! It was 210 after about 45 seconds!!!!

My mind was racing with what this could be. The light changed after about a minute and I took off, it was laggy. I drove about 1/4 mile to my sub-division and when I turned in it felt like the motor had quit. Power steering gone.

I checked the gauges and the engine was going. I put it in neutral and tried to give it some gas, nothing. At least nothing noticeable. I turned the key off to kill the engine.

After about 10 seconds I tried starting it, it started, but wasn't acting right.

I drove the rest of the way home, all at 210 degrees.

With the engine running I popped the hood and there was oil burning off the intake exhaust side of the engine. I squeezed the upper hose, nothing, seemed bone dry.

I heard the over flow gurgling, and heard a slightly different sound, but in step with the gurgling coming from the radiator cap. It was turned slightly and air was either being sucked in or pushed out. I turned it slightly and both the noise that was coming from it and the gurgling in the overflow stopped.

I killed the engine and turned on the electric fan bypass and monitored the temp.

After a bit it started to drop. I checked the upper hose and now it felt full.

Fast forward with me cooling, monitoring, spraying the radiator with the hose etc.... then killing it again and leaving the electric fan on I got it down to 197.

At this point I took the radiator cap off. It looked like it could use some coolant, so I cranked the motor back up and started filling the radiator. It wasn't empty but it was low. Maybe a gallon, perhaps less. I thought to check this because even after it stopped smoking and running right the temp wouldn't drop below 230 with the A/C off and the electric fan on!

So now the sequence of events (that I'm all too familiar with) seems to be...

The engine gets up to 230, then goes beyond. The cooling system can't cope with the increased pressure so it starts dumping coolant to the over flow and the over flow starts dumping it to the ground (guessing).

At a certain point there isn't enough coolant in the system to circulate through the upper hose so the temp sensor starts measuring air temp, which seems to be 210 degrees unfortunately.

The motor temp increases, but I can't tell because there's no coolant moving over the sensor.

It gets so high that detonation starts to occur and power is lost.

Once I filled the radiator up and ran it for 10 or 15 minutes, the temp was about 197 degrees.

There is no water in the oil, and no water being ejected from the tail pipe.

224

[Carves]

Just looking at your last coupla posts ...

FWIW ... that sequence of events could all be attributed to a dodgy rad cap/warped filler neck.

Is it "unscrewing"/backing off from "locked" ... on its own do you think ?? ...

The CTS needing to be immersed, for correct fluid readings ... is one of the main reasons - I like the digital gauges and bolt on thermo-couplers/sensors as an, extra monitoring system..

Just a thought too ... have you ohms tested the CTS for correct operation ?? ... Theres a results chart in the FSM for ohms values at various temps ... Yours is obviously ballpark at the moment but it wouldnt hurt to check it.

... and yep ... once you've lost coolant ... you've lost cooling ...
That approx gallon you replaced - is about a third of the systems, barely adequate capacity ...

[Mudderoy]

Just looking at your last coupla posts ...

FWIW ... that sequence of events could all be attributed to a dodgy rad cap/warped filler neck.

Is it "unscrewing"/backing off from "locked" ... on its own do you think ?? ...

The CTS needing to be immersed, for correct fluid readings ... is one of the main reasons - I like the digital gauges and bolt on thermo-couplers/sensors as an, extra monitoring system..

Just a thought too ... have you ohms tested the CTS for correct operation ?? ... Theres a results chart in the FSM for ohms values at various temps ... Yours is obviously ballpark at the moment but it wouldnt hurt to check it.

... and yep ... once you've lost coolant ... you've lost cooling ...
That approx gallon you replaced - is about a third of the systems, barely adequate capacity ...

A few days ago I noticed the top coolant temp rising day after day. This usually means that the coolant level is getting low. After getting home Monday evening I checked the fan clutch, but didn't come back out to check the radiator level.

Tuesday morning I took the cap off to check the coolant level and it was full. I put the cap back on and I don't think I twisted it all the way back on, at least that was my thought when I found it wasn't tight.

[Mudderoy]

225

So I took this screen capture about 3 miles before getting to the office. Air temps 81 to 83 degrees, and with A/C full blast.

After my post last night I got to thinking about another time I saw something similar to this. It was the 99 shortly after we got it. The lower hose blew out and most, if not all of the coolant ran out. The sensor was measuring air temp and showing a very nice 210 degrees, when actually the motor was much hotter.

No hose blew out on my 1998, and I didn't see any coolant anywhere. However my theory currently is that as heat and pressure built in the system the coolant evacuated to the overflow bottle on then on to the ground as I drove. Probably over two days of driving when it was at 230, or it could have just happened yesterday.

I think it just gets too hot for the cooling system to cope and the coolant escapes, causing more heat and more coolant loss. It's obvious what the result will be.

Why is it so hot? Under hood temps approaching 200 degrees. Air temps near 100 (probably over). A small head gasket leak adding fuel to the fire.

[89Laredo]

What obd reader do you use?

[Mudderoy]

What obd reader do you use?

An Android phone running...

226

A generic bluetooth enabled elm327 based OBDII scanner.

http://obd2store.com/images/obd2/bluetooth%20ELM327.jpg

For example... :link: (http://www.ebay.com/itm/Mini-ELM327-Interface-V1-5-Bluetooth-OBD-II-OBD2-Auto-Car-Diagnostic-Scan-Tool-/310371228800?pt=LH_DefaultDomain_0&hash=item4843911c80)

[89Laredo]

That's what I figured. Was wondering if those things worked.

[Cheromaniac]

One thing you haven't tried is removing the thermostat to see if that helps at all. It's just possible that your t'stat is sticking, causing the temp. to rise quickly and drop again. Test the t'stat in a saucepan of boiling water and see if it opens properly.

[Mudderoy]

One thing you haven't tried is removing the thermostat to see if that helps at all. It's just possible that your t'stat is sticking, causing the temp. to rise quickly and drop again. Test the t'stat in a saucepan of boiling water and see if it opens properly.

New thermostat (as with all things) can be bad new, or go bad at any time, but this one was installed about two months ago. It's still good advice, thanks.

[Mudderoy]

228

229

What a difference. Now which was it? Filling up the radiator or the air temp?

It never got about 212 yesterday.

[Carves]

Primarily the amount of liquid in the system being correct - I would think.

Just a matter now - of ensuring the level is always right, and noting any running temp changes - in different ambients.

Like you ... I do think that 80*/90* ambients are a critical point for the system - as thats when I've noticed the most change in the stability of the coolant temps ... and sometimes temp spiking ... in three 4.0l jeeps.

In my case ... lower eth-gly concentrations and a 190* t'stat ... and noon siestas ... was the easiest, high ambients fix - on a TJ from new ...

My first TJ warranty claim at 7days of ownership .... Gimmee a new thermostat, this ones not opening properly ... So they did ... which I also ripped out, 7days later ... and replaced with an aftermarket one. :rolleyes:

Doing the same helped with the XJs ... but my biggest XJ improvements in regards to getting a stable XJ running temp ... were the 2row copper rad and having a seperate tranny cooler arrangement.

Other little "mods" & adjustments Ive done, are just icing on the cake imho.

[willtodo]

Has any one tried to fab up a good shroud to fit a large electric fan that will cover the entire radiator,,, set it up with a thermo switch,,, i have a set up on another 4x4 with 16 inch fan that pulls around 3000cfm,, its set up to turn on with computer and ive got a alternate toggle for when im running ac and would like it to be cooling befor it gets up to temp,,, it works real well,,,i intend on doing the same with the XJ,,,deleat the small electric and engine drivin fan ,,,, also on the other 4x4 i have auxilary engine oil cooler routed under bed with fan settin ontop of it,,also controled with comp and toggle,,,

[Mudderoy]

Has any one tried to fab up a good shroud to fit a large electric fan that will cover the entire radiator,,, set it up with a thermo switch,,, i have a set up on another 4x4 with 16 inch fan that pulls around 3000cfm,, its set up to turn on with computer and ive got a alternate toggle for when im running ac and would like it to be cooling befor it gets up to temp,,, it works real well,,,i intend on doing the same with the XJ,,,deleat the small electric and engine drivin fan ,,,, also on the other 4x4 i have auxilary engine oil cooler routed under bed with fan settin ontop of it,,also controled with comp and toggle,,,

http://www.xjtalk.com/showthread.php?t=8001

[BlueXJ]

Has any one tried to fab up a good shroud to fit a large electric fan that will cover the entire radiator,,, set it up with a thermo switch,,, i have a set up on another 4x4 with 16 inch fan that pulls around 3000cfm,, its set up to turn on with computer and ive got a alternate toggle for when im running ac and would like it to be cooling befor it gets up to temp,,, it works real well,,,i intend on doing the same with the XJ,,,deleat the small electric and engine drivin fan ,,,, also on the other 4x4 i have auxilary engine oil cooler routed under bed with fan settin ontop of it,,also controled with comp and toggle,,,

This sounds interesting (both coolant and oil) do you have photos of either or better yet both???

[4.3LXJ]

http://www.xjtalk.com/showthread.php?t=8001

I guess I should add to that write up. I also now have added a 2200 cfm Derale fan. This gives me an incredible 7000 CFM with both fans on.

[willtodo]

This sounds interesting (both coolant and oil) do you have photos of either or better yet both???

ive tried to post pics before but have had problems ,,,,guess ill have to load into photobucket,,,,,