B6 S4 - pressurising??

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shaz

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Quick question guys, when a S4 has reached it's temp at 90 car is hot etc if the coolant cap is lifted partially should it pressurise? And spill out from the overflow hole underneath...?

Or is this a sign of head gasket problems,?

Has been driven and didn't overheat at all - just built up pressure which I didn't think was normal,

Any advice??
 
it should pressurise ... the water and air expand and should be locked in , so when the cap is removed the pressure escapes
if it doesnt pressurise it could potentially be leaking or possibly have a gasket problem

head gasket problems on s4,s are few and far between
 
Thanks pal, I'm going to have to get a second opinion, it's my friends car but I noticed it didn't overheat but when I took off the cap partially it through out some pressure a friend of mine said to me that it shouldn't do that.

I remember I used to remove radiator cap off my old Honda to release any air locks from the rad but this chucks water out!

Are there any other tell tale signs of the head gasket being at fault?
 
Check to see if their is oil in coolant tank or white stuff under the oil cap is a good place to start.
 
The system is meant to pressurise that's why its unsafe to release the cap when hot and risk being scalded by hot steam and boiling water
 
Ok thanks for the tips guys...

I'm gonna drive it for a bit longer see how it goes,
 
Expansion tank caps are prone to failing so may be worth sticking a new one on as they're only about a fiver from TPS.
 
Had a new expansion tank fitted but didn't get a new cap, might get one actually
 
That's normal, it's pressured to raise the boiling point. Removing the cap releases the pressure suddenly, so overflows.
 
Had it pressure tested today by a VW Audi specialist - all is well - no leaks found.

Thanks guys
 
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