Finding a leak

[moojw]

Hi all, I've got a 1.9 DG with a slight leak, i'll fill in the details, back in December in France the waterpump/alternator belt went, when I was replacing it I noticed the bearing on the waterpump was rough so decided to change both the pump and belt, all was good, but about half way back across France we saw water spots on the back window and we'd lost about 2 litres, but I can't see any leak anywhere.

Back in England we drive about town and if we take it steady on the motorway it seems ok, but push it up to 70mph and again it blows the water out, but dammed if I can see any sign of a leak.

So any ideas of how I could track this down?
Is it possible to do some sort of DIY pressure test?

any suggestions welcome and appreciated

[ajsimmo]

It might be pressurising the cooling system, and passing coolant to the expansion tank, then spilling out the vent holes at the top tab. When it cools it'll draw some of the coolant back through the cap into the header tank (and stop leaking), but still leaving the expansion tank level abnormally high.

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[moojw]

Thanks for your reply

I've bought a new header tank cap last week just in case there was an issue with that but no change, although this one is blue and the last was black but I was informed they are the same.

My expansion tank doesn't have much in it at all, and in the last 11yrs that I've had the van it's always been the same, very low to the point of being almost empty, but I've never had an issue even with long motorway drives.

I was thinking maybe I've disturbed something and it's a minor leak but increases with higher revs and pressure, or would you say i'm barking up the wrong tree?
That's why I was thinking if I could get a pressure test then I might be able to locate the leak.

[moojw]

Had a pressure test today and they don't see any leaks, sounds good but I still have an issue so confused, maybe its only under pressure at full heat, something that only gives at full heat and pressure on expansion. Any ideas peeps! Heading from Wales back to London very soon

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[moojw]

Tbh, we have found a great stop over, no site fees, Soft play in 50yrds plus a pool (heated) great, bar n grill has closed so a huge parking area

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