Posted: Wed Jul 31, 2019 4:17 pm Post subject: Coolant over pressuring from cap
Can anyone help pls I'm going insane.
My car was blowing the cap on the header tank when driven ..I then re routed my cooling system to reflect a basic system as shown on here without a heater as I was originally using a bmw stat.
My car warms up nicely, fans kick in and radiator gets hot, coolant is constantly circulating back into the bottle nicely...no leaks as I used a pressure kit and it held pressure.. it still blows through the cap.
I'm using a corsa header tank which was half full with coolant, is this too much to account for the expansion?
as you have drawn it, the expansion tank is part of your circulation. That is not how it should be.
The expansion tank only needs 1 hose feeding the circulating system, but it should not be part of it.
you should bypass the tank, ant connect manifold to stat, with a T somewhere in the bypass, where you can put the expansion tank.
Also, what I have noticed on my system, because of the setup, I use more coolant in my van, compared to when the engine was in the original car. as a result, you would be needing a bigger expansion tank, or keep a lower level in the expansion tank, to keep more room for actul expansion.
also, if pressure keeps coming back, it can also be a headgasket issue. _________________ 1973 BayWindow running 1.9 110 bhp TDI with flipped gearbox.
as you have drawn it, the expansion tank is part of your circulation. That is not how it should be.
The expansion tank only needs 1 hose feeding the circulating system, but it should not be part of it.
you should bypass the tank, ant connect manifold to stat, with a T somewhere in the bypass, where you can put the expansion tank.
Also, what I have noticed on my system, because of the setup, I use more coolant in my van, compared to when the engine was in the original car. as a result, you would be needing a bigger expansion tank, or keep a lower level in the expansion tank, to keep more room for actul expansion.
also, if pressure keeps coming back, it can also be a headgasket issue.
Many thanks for your reply. Is it correct as the attached picture now. Ive also got an expansion tank i may use from the header tank
Bottom of the header tank to a tpiece, one going to the thermostat smaller hose connection and the other to the connection on my coolant manifold (im using a reversed one)
Still, even after putting this right it is possible that the capacity of the corsa header is too small. you could try running with real low level of coolant, just visible in the header tank to see if this results in less pressure _________________ 1973 BayWindow running 1.9 110 bhp TDI with flipped gearbox.
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