Renix cooling upgrade

[BlueXJ]

My Renix has always been a bear to purge the air from the system. The traditional way involved putting the rear on a hill or a set of ramps. Then removing the temp sensor from the rear of the head. They can be fragile and I have broken more than one.

I was looking at a pic that Melissa posted about trying to help a member find a rare bracket. And in that pic was a H.O. Thermostat housing. I went out and checked my Renix and it looked like it would fit without modification.

I asked her and she shipped it to me. There is a plug 3/8"NPT as I recall. If you pull that plug and replace it with a radiator type drain you then can purger the cooling system from that drain valve. The drain valve now becomes the high point in the cooling system. No more ramps or hills, and no more broken temp sensors in the rear of the head. I call this modification the "Melissa fix for Renix cooling system purges".

I doubt if any pics would help so none are included. Everyone with an H.O. 4.0L engine has one of those plugs and any Renix owner can see that unless they have a high flow T-stat housing, does not have that plug.

[warrpath4x4]

yah thats a pretty common fix for purging the air out of the renix systems, i did this on mine when i put the new radiator in. i bought all my parts brand new and it was like just over $10. it also helps if you drill a small hole in your thermostat and place it at the top.

http://i59.photobucket.com/albums/g293/smalltowncowboy1980/XJ/006-1.jpg

[96xj]

what dose every body mean when they say Renix and how can i tell if my is ?

[warrpath4x4]

renix was the first gen 4.0L before the H.O. 4.0L came out in 92 (i believe). the renix has a closed cooling system from the factory and the H.O. has an open cooling system (radiator cap on the radiator).

[NickM]

Correction, Renix is all 4.0's from '87 through '90.
'91 on up are all HO and open cooling system (coolant bottle is NOT part of the pressurized system).

Nick

[novastique]

Thanks for asking that, I was about to ask myself!

[BlueXJ]

Thanks warrppath for the pic. I did not have access to a camera while doing the modification.
I have been working exclusively on Renix stuff for over 10 years and have never seen this modification done. You said it is common but not to many people. Again thanks for the illustrative photo.

[xj4lifetwo]

Just as a side note the water outlet can be had aftermarket from Hesco they also offer a high output water pump. I have gone a step farther and put a Moroso rad cap in the top hose (highest point in the system) got rid of the bottle for a standard overflow from Auto Zone and went to a late model heater ctl valve. No more "burping" issues or heating. Oh I also lifted the rear of the hood 1/2" for cowel induction cooling.

[BlueXJ]

Just as a side note the water outlet can be had aftermarket from Hesco they also offer a high output water pump. I have gone a step farther and put a Moroso rad cap in the top hose (highest point in the system) got rid of the bottle for a standard overflow from Auto Zone and went to a late model heater ctl valve. No more "burping" issues or heating. Oh I also lifted the rear of the hood 1/2" for cowel induction cooling.

If you want to keep the pressure tank and are tired of the cheap chinese ones available now you can upgrade as I did.


http://www.macsradiator.com/replacmentjeepradiatorfilltanks.aspx

[Jeep88]

where did you buy the cooling system from

[uberxj92]

i have a 90 renix. i changed it over to an HO cooling system. it was very easy & runs so much cooler. that ridiculous water bottle on the renix system is the root of all evils!!! once it gets hot just once it wont work correctly any more.all you need is the radiator from a 91 to 96 xj, & a barrel hose connector. then you can make your own overflow bottle.

also, just as an after thought, you can drill 1/4" hole in the thermostat. it wont hurt the cooling & it will burp the air out on its own

[MaxxTraxx]

This will be my first Texas summer with a Renix jeep...seems to do fine for now though...but, it did over heat slightly the other day while siting in traffic in low 80's weather...as soon as I got going again went right under 210. It was also good all day yesterday on the trails.

Is it common for it to overheat easily?

[uberxj92]

it shouldnt just sitting in traffic. however even my 92 has done that, indicating an issue. i ended up checking everything, turned out the electric fan wasnt coming on all of the time. i live in florida so a great cooling system is important. i wired the electric fan to a switch inside the jeep that i can turn on & off. that seems to make a huge difference, i used a relay system so the fan actually gets the right amount of amperage & turns faster.
then i put an aftermarket electric fan on the front, middle of the a/c condenser pushing inwards & wired it to a relay & switch as well.
as long as i do not lose too much coolant to overflow she runs cool.
i still have the hood vents to install & i am going to install 2 tranny coolers & bypass the tranny coolant part of the radiator. i will put fans on the coolers.

[Mudderoy]

Just as a side note the water outlet can be had aftermarket from Hesco they also offer a high output water pump. I have gone a step farther and put a Moroso rad cap in the top hose (highest point in the system) got rid of the bottle for a standard overflow from Auto Zone and went to a late model heater ctl valve. No more "burping" issues or heating. Oh I also lifted the rear of the hood 1/2" for cowel induction cooling.

I couldn't make myself spend $300 for a waterpump so I got the flowkooler for $100, still pricey. Makes a difference. I paired it with a high flow therm and therm housing.

[BlueXJ]

Use a 4.0L WP from a GC. They have better flow rate and keep a Renix era Jeep very cool when used in conjunction with a GC fan clutch.

[steph74]

$300 or a water pump ? Aren't the regular ones like $30 ?

I am going to check the cooling system really good on my renix when I change the head.

I have heard about the drilling a hole in the thermostat before.... can someone elaborate a little ?

I don't quite get the idea of the modification of the water outlet BlueXJ shows.
I would think that this is not the highest point of the system ....

[steph74]

Use a 4.0L WP from a GC. They have better flow rate and keep a Renix era Jeep very cool when used in conjunction with a GC fan clutch.

Translation ? lol
Since I am going to change the head, I figured I might as well change the water pump and stuff....

What does that mean ? getting a wterpump from a grand chero=kee ? is it direct fit ?

[Mudderoy]

$300 or a water pump ? Aren't the regular ones like $30 ?

I am going to check the cooling system really good on my renix when I change the head.

I have heard about the drilling a hole in the thermostat before.... can someone elaborate a little ?

I don't quite get the idea of the modification of the water outlet BlueXJ shows.
I would think that this is not the highest point of the system ....

Yeah but the HESCO is a high flow water pump. So is the FlowKooler. $117 at Summit I believe. I've gone through about 5 $30 pumps.

[xj4life2]

Renix ere Jeeps run at 210* normally, at least all that I have worked on and mine included. There are a few things you can do:
1. drop the t stat to a 180*
2. put a moroso in line rad cap in the top hose and a regular overflow tank. You will have to go to a Chevy style heater control valve.
2. Use a Nissan fan t stat (it comes on at 185* rather than the 192* in the Jeep)
3. bypass the electric fan all together and make it manual. It can by wired to be manual /computer controlled by going off the relay (orange wire)
Hope this helps by the way I would also recomend a secondary guage and a sender in the front of the motor , the current sender is in the rear and is not always accurate.
Hope this helps

[MaxxTraxx]

BlueXJ
Use a 4.0L WP from a GC. They have better flow rate and keep a Renix era Jeep very cool when used in conjunction with a GC fan clutch.

I'll have to try that as my fan clutch is about gone hence my slight overheating issues...