cooling system

[Thomass]

Back home, from a trip in to Luxembourg, i decided to replace all of the water-hoses. Just for the reason that they didn't feel good, i mean very soft and porous.
Since i have this rig, on the joints, Hose to metal, there is a white kind of stuff around it.
If I clean it of, it will be back after a short wile using the rig. It looks like chalk or aluminium oxide.
Inside the hoses there is nothing to see (except for one hose where the inner layer came lose from the rest and probably causes the prior cooling problems the rig suffered last time from)
I just wonder where this white stuff comes from, and what causes it. And not unimportant, is this bad for the engine ???
my cooling liquid is is an mixture of an antifreeze and de-mineralized water on a 50/50 base.

any body any suggestion ?

[Thomass]

as of this morning,i decided to clean out the cooling system, by means of flushing the engine and all other cooling parts of my rig with plain water.
I used also an liquid that will remove chalk.
At the beginning the watter was clear, and just when i wanted to switch of the flushing-pump, the water became brown and filthy, so i left it flushing for a wile longer.
Now all is installed back on the rig, and did make a first test run the cooling stays within reasonable temp. Only in the mountains (for you hills) the engine becomes to warm...
The white stuff was a kind of chalk, what already contaminated the engine before i bought it.

**** I should buy a new digital camera ****

Th