Rad caps

[NicBowman]

Hi

This comes up lots of times, surely the pressure cap should be on the plastic tank, and the fixed cap on the metal. The plastic tank is a generic part used on lots of cars and always has the pressure cap. The metal tank is for filling only? Surely?

Nic

[shpub]

It depends.... War and Peace on this in the bible in the cooling chapter. Bear in mind that this is not a normal car and normal bits are frequently used in a different way.

Search the archive and you will find nearly all the possibilities.

[greenv8s]

Yes, but the other way round doesn't work too bad. The two arrangements have different failure modes, so depending what problems you have, swapping the caps over may cure it or at least hide the symptoms. But ideally, if everything is working correctly, the pressure cap should be on the plastic expansion tank and the blanking cap should be on the metal swirl tank.

[WildfireS3]

Mine seems to work with the pressure cap on the swirl tank and the blanking cap on the expansion tank. Car runs fine and doesn't overheat, except when the hose between the two tanks was blocked and then water blew out of the swirl tank.

[shnozz]

WildfireS3 said:

Mine seems to work with the pressure cap on the swirl tank and the blanking cap on the expansion tank. Car runs fine and doesn't overheat,

as did mine. the only time i had any trouble was when the rad cap got a bit long in the tooth and water was going to the expansion tank and I could hear it bubbling away in there after the engine was switched off. New rad cap on teh swirl tank and no troubles at all.

[WildfireS3]

shnozz said:

the only time i had any trouble was when the rad cap got a bit long in the tooth and water was going to the expansion tank and I could hear it bubbling away in there after the engine was switched off.

Oh is this bad?

Mine does that. I have another rad cap at home, it isn't long sprung though.

[Roy C]

WildfireS3 said:

Mine seems to work with the pressure cap on the swirl tank and the blanking cap on the expansion tank.

That's how they left the factory.