Cooling system pressure

[race watcher]

I have run into this problem in the past.. What I found most of the time I had an air pocket somewhere in the cooling system.

[rod]

the cap is obviously good, or it would not hold pressure that long. there would not be any leaks in the cooling system or it would not hold pressure that long. most likely an air pocket in the system somewhere. you may have to raise the front of the car way up to get it to 'burp'. after the season is over, pull the 'stat and drill at least one 'air bleed' hole in the 'stat housing.

rod in AZ

[ROY]

Thank You everyone that gave suggestions.I do not run a T-stat,so no restriction there.The air pocket makes sense,even though I fill the system slowly and with the upper hose off at the radiator and turned so as to be the highest point in the system.I spoke with two engine builders today,they both said it had to be blown head gaskets even though the gaskets do not show any damage!! ROY.

[Ed Wright]

I would pressure check the cap. May not be releasing at the proper pressure. Five to seven psi would be plenty. I actually don't run any pressure in mine. I just cut a small "V" in the rubber gasket. Never a problem. I jack the front of my car up when I fill the cooling system, and run my electric water pump while topping it off.

[Alex Denysenko]

the only time I have evetr seen this on a SBF is when someone installed the head gaskets backwards.

[Dwight Southerland]

Originally Posted by Ed Wright

I would pressure check the cap. May not be releasing at the proper pressure. Five to seven psi would be plenty. I actually don't run any pressure in mine. I just cut a small "V" in the rubber gasket. Never a problem. I jack the front of my car up when I fill the cooling system, and run my electric water pump while topping it off.

I was going to suggest a "no pressure system". I have always used a cap that seals at the top but no pressure mechanism. There are advantages.

[Wade_Owens]

Originally Posted by Dwight Southerland

I was going to suggest a "no pressure system". I have always used a cap that seals at the top but no pressure mechanism. There are advantages.

x2

Wade

[Tom Goldman]

I use Evans NPG coolant with a zero pressure cap.
my spare engine is an old Comp engine that has some heads that leak a little, not unlike some SS heads.
This stuff works great and is race legal as it is not an ethelyne glycole base and cleans righ up.
It boils at 360 deg F at no pressure and has a very low expansion rate.
not cheap, but it works great and can be reused for several racing seasons.






http://www.evanscooling.com/products/coolants/npg-2/