pushing coolant

[blizz99]

My coolant is pushing out of the reservoir while idling/driving. It'll suck whatever is left back into the system(which is little) once the car cools back down as normal though. My compression is 170-162-170-175. There's no coolant mixing into the oil, no sweet smell from the exhaust, no smoke from the exhaust. I've pulled the tstat and put into boiling water to see if it opens and it checks out good. What can be the problem?

 

[bryanwheat]

Could be the radiator cap. I would pull it off and check the seal on it. If you are getting a good seal on the cap than next thing is to pressurize the cylinders and see if that air is leaking into the cylinders.

 

[blizz99]

I've pulled the cap and it appears that the seals on it are good. No rips or damage. If it's leaking from the cylinders, wouldn't the coolant that's left in the reservoir NOT be sucked back into the tstat housing?

 

[junkshot]

Had the same issue was my head gasket. Used a autozone block tester to check it pretty easy to use. Might try it or so you can rule it out anyways. Also, I had already pressure tested the radiator system good, had good compression in all cylinders. Was just a small pin hole leaking a little exhaust into my system caused it to slowly push out coolant. Good luck.

 

[bryanwheat]

I've pulled the cap and it appears that the seals on it are good. No rips or damage. If it's leaking from the cylinders, wouldn't the coolant that's left in the reservoir NOT be sucked back into the tstat housing?

Well your options are a bad cap or a leaking head gasket, so it is either or. When the engine is cold with the radiator full, cap on and the hose to the reservoir unhooked squeeze the upper hose and see if coolant comes out of the reservoir hose.

 

[blizz99]

Well your options are a bad cap or a leaking head gasket, so it is either or. When the engine is cold with the radiator full, cap on and the hose to the reservoir unhooked squeeze the upper hose and see if coolant comes out of the reservoir hose.

Just tried this and no coolant came out. So I guess it's the head gasket any way to test it out before I take the head off?

 

[bryanwheat]

Just tried this and no coolant came out. So I guess it's the head gasket any way to test it out before I take the head off?

Of coarse, you can use a cooling system pressure tester, pressurize the cylinders with coolant in the radiator, or use a hydrocarbon detection kit in the coolant.