Loosing coolant from header tank

[platty]

Hi,
I am loosing coolant from the header tank after driving for an hour. When stopping coolant is dripping from header on to exhaust and also sprayed around engine bay. Fitting a new blue "dalek" cap has made no difference. Pipe from cap to top up tank is dry. Level sensor seal fine. The top up tank levels stay the same and I cant see any leaking hoses. Engine temp spot on! Anybody got any ideas?

[andisnewsyncro]

system needs bleeding? but if it's "sparaying round" you must have a leak somewhere

[syncrosimon]

I have found that the internal expansion tank will leak just prior to failure. They seem to crack around the seam. You can plastic weld the seam, or just replace. Also check that the level sensor screwed into the top (with wires coming out) is not leaking. This can come loose, or it cam also crack and leak. You need to take the tank out and have a good look at it.

Simon.

[Aidan]

if buying a new expansion tank get one from VW, complete with new genuine cap - gsf ones seem to be factory seconds not for quality, often weep from seam as described