pressure cap

[blue_nosed]

Can anyone help? I,ve had an s3 since november when warmed up turn engine off occasionally leaks coolant from the expansion tank,checked the caps and according to the bible they were the wrong way around so, changing them to pressure cap to swirl tank and sealing cap to expansion(plastic overflow)tank under pressure it constantly leaks from the overflow pipe,

1.do i have to much coolant?
2.do i need to replace both caps?

[doddze]

does it settle down to a set level in the swirl pot after?

The plastic tank is there to take any excess water from the system...

mine always settles to 2 inches below the swirl pot lid (pressure cap) and the plastic overflow almost empty...

but if it worked fin before you changed them...... change them back

therer seems to be no right or wrong way for the caps just the way that works for your car

[blue_nosed]

i think i,ll run the engine (caps the correct way) and see if it still looses water when eccess has gone out of the system, Hopefully i,ve had to much coolant in?Thanks anyway

[sotons2]

If it helps, the level in mine at cold is about 1 inch below the top of the swirl pot with the expansion tank about half full.

If I overfill it, any excess is dumped on the driveway - particularly after a 'sprited' run

[GreenV8S]

Oh no here we go again!

Blank cap on the swirl tank, pressure cap on the header tank. If you get a leak via the overflow, the pressure cap isn't holding pressure. Replace it, and check that the sealing surface in the neck of the header tank isn't corroded or damaged. Also check for leaks from the link pipe between the swirl tank and the header tank, if necessary replace the link pipe. If you get a leak at the top of the swirl tank, replace the blanking cap and check the sealing face isn't corroded or damaged.

[blue_nosed]

hi again thanks for the replies it seems to be a difference of opinion between Steven Heaths (Bible) and the original set up, New pressure cap 1st and see how it goes

[GreenV8S]

Both cap arrangements work as long as there are no faults in the system and both have their supporters. Whichever way round Steve put it in his books, half the people here would disagree with him!

Putting the caps the 'wrong' way round works and can avoid problems if the header tank or connecting pipe are damaged and won't hold pressure. However, if there are no faults then it is better to put the pressure cap on the header tank.

[blue_nosed]

thanks for your reply forgot to mention all new hoses etc, I,ll leave it as it was (with new pressure cap) and see how it goes. Think i will need a manual switch for fan Is this easy to fit?

[GreenV8S]

Yes.