MartinL2

Please can anyone advise why when the engine has been running for about 10 minutes it blows coolant out if the expansion tank cap. When I then stop the engine it seems to blow out a bit more coolant. Cheers Martin 

Hi Anthony, funny you should say that, my cap looked perfectly OK but was also 22 years old. When I refilled there was alot of air to get out, I now need to get some anti freeze in there but the only way I seemed to get the air out was by blowing the hose pipe down the heater pipe so not sure how I'm going to get the air out when I have added the antifreeze..Martin 

Thank you for all your responses, engine flushed, replacement expansion tank cap fitted, refilled, and all air pockets vented, no water blowing out the top on test drive. Just need to get a bit of antifreeze in their now. Martin 

Thank you for all your responses, I have purchased a new cap today, going to try flushing and refilling and fit new cap and see how it goes. Can anyone advise the best way to refill avoiding any airlocks? The car is fitted with a heater. Martin

Obviously also vented it from the top of the radiator as well.

Obviously also vented it from the top of the radiator as well.

I am pretty sure I have only had this problem since replacing the coolant. The caterham is fitted with a heater and I have disconnected a heater pipe to vent it from there.

Is there only one cap type to suit this expansion tank, or are there different caps set at different vent pressures according to actual engine type. To be honest I drained the coolant system, flushed it through, refilled with almost neat red anti freeze and then it seemed to blow out of the expansion tank. Bit by bit with keep refilling, the coolant is probably just water now, and maybe the reason for the rusty coloured coolant..Martin 

Hi Jonathan, if you could send me some info, that would be very much appreciated...Martin 

Hi Jonathan, thankyou for your response, I don't think it has an o ring, are these caps set to vent at a specific pressure  and if so can they start to stick causing the coolant system to over pressurise, causing water to flash to steam and leak out through the cap..Martin

Please can anyone advise why coolant keeps on blowing out of the expansion tank filler cap. Could the cap be faulty and would anyone know the part number for this cap and the best place to source one from? Thank you Martin