Too much pressure in coolant tank

[Steve Tinker]

If you have excess pressure in the cooling system then the pressure must be coming from somewhere.
1)It can't be the pump as I doubt it could compress up to ~ 20psi even with near boiling point water.
2) It could be a blocked engine / radiator vent line (#11 & 12 in diagram) but ??

I'd hate to think that you have a cylinder head crack opening up when hot and combustion gasses are "pumping up" the cooling system....

[JFP in PA]

Originally Posted by Steve Tinker

If you have excess pressure in the cooling system then the pressure must be coming from somewhere.
1)It can't be the pump as I doubt it could compress up to ~ 20psi even with near boiling point water.
2) It could be a blocked engine / radiator vent line (#11 & 12 in diagram) but ??

I'd hate to think that you have a cylinder head crack opening up when hot and combustion gasses are "pumping up" the cooling system....

This is exactly what I posted to the OP on another site (http://www.renntech.org/forums/topic/48478-too-much-pressure-in-coolant-tank/), and suggested running both a leak down on the engine and checking the vapor above the coolant in the tank for combustion gases using one of these:



That excess pressure is coming from somewhere other than the cooling system.....

[bglz42]

JFP, thanks for your answers. It is not that I didn't believe you...I just was hoping for another verdict, LOL! Sort of like getting another opinion when the diagnosis is cancer!

[JFP in PA]

Originally Posted by bglz42

JFP, thanks for your answers. It is not that I didn't believe you...I just was hoping for another verdict, LOL! Sort of like getting another opinion when the diagnosis is cancer!

There are only a limited number of ways to get a cooling system to over pressure; over heating is the obvious one, but a combustion pressure leak into the cooling system is also a reality.

To use your cancer analogy, it is time to stop speculation and start diagnostics. A leak down will show if one or more cylinders are losing gas pressure, the presence of combustion by products in the cooling system would also be a dead give away. If neither of these check out positive, you will have eliminated a major probability and can move on to look at the cooling system itself.

But you have to start someplace.............

[nicecar]

I just replaced cap and o ring and still having problem. Could it be fixed by replacing the entire valve?

[nicecar]

If the coolant mix was slightly watery would this cause the condensation?