Coolant Pressure test

[Rawze]

(12-08-2017 )Pete1990 Wrote:  Im pressure testing the coolant system it has NO leaks outside im pumping it to 15 PSI Which is cap rated... When the engine is COLD there is no drop at all.. it sits at 15 PSI for hours.. When the engine is hot though it loses PSI it loses around 4-5 PSI every hour... This has me thing head maybe now?
This is on a 07 ISX cm870

It is standard practice to always pressure test the coolant system 5 lbs above the cap rating. You do so by removing the pressure relief cap and installing the pressure test kit in its place. Some trucks like my prostar, this is the fill cap, but on other trucks like volvo and pete's/kw's with the plastic tanks, it is the pressure relief cap on the drivers side and not the fill cap. I have met quite a few people who only pressurized their truck to 15 psi, never find the leak, then go back and pressure it to 20 psi and find the leaks. Sometimes that is what it takes.

Also, too many people overlook the pressure relief cap itself going bad. Relief caps are cheap, so buying a new one never hurts.

I would recommend reading this ....
http://rawze.com/forums/showthread.php?t...5#pid15895