Pressure in Coolant reservoir

[rshunter]

Isn't it normal to have pressure in the coolant reservoir shortly after the engine is turned off. Am I correct in assuming the head gasket test is to see if pressure remains after the engine cools, say overnight?

 

[zakkb787]

You check the pressure at the upper radiator hose, not the reservoir.

 

[Dkatubi06]

We need more info on the truck broski. My Lb7 in the 40,000 mike I had it in my truck I was always able to squeeze the rad hose even after a two hundred mile non stop run. SOME pressure is normal and should receded over night.

Are you loosing coolant? Puking out the overflow tube? Some would say replace the radiator cap before doing anything else they pop off @ 16 psi. If your seeing that kind of pressure you MAY or MAY NOT have a head gasket issue

 

[JoshH]

Pressure is normal, but if it holds pressure overnight, that is generally a sign of bad head gaskets.

 

[rshunter]

We need more info on the truck broski. My Lb7 in the 40,000 mike I had it in my truck I was always able to squeeze the rad hose even after a two hundred mile non stop run. SOME pressure is normal and should receded over night.

Are you loosing coolant? Puking out the overflow tube? Some would say replace the radiator cap before doing anything else they pop off @ 16 psi. If your seeing that kind of pressure you MAY or MAY NOT have a head gasket issue

I had gone to look at a 2006 3500 and the man selling had driven it to meet me. Not far but enough to get the engine up to normal operating temps. I am Newb to the diesel world and had tried to watch some "what to look for when buying a duramax videos" and they mentioned the coolant reservoir test for head gasket problems. I just wanted to make sure I understood the process correctly. When I unscrewed to cap to the reservoir it released pressure. Not spewing,but enough to give me pause as I continued to unscrew the cap. Seemed perfectly normal to me understanding the engine was warm and off. Just wanted to double check with the experts.

 

[Dozerboy]

Ya if the HGs are bad it will be a lot of pressure not just a whoosh sound and maybe a little coolant blown out. If the reservoir is anywhere near the full mark it will blow it out the Like nobody’s business.


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[Dkatubi06]

A little pressure is normal, if it comes out like a shook up soda then you have a problem. Did you test drive it your self and re check it?