Coolant leak or something else?

[kervinmervin]

I realise there are loads of threads on leaks, but can’t quite see one that aligns.

I’ve been chasing what I assume to be a leak for a long time, I’ve changed various parts and the waterjacket seals have been done fairly recently. The level in the header tank drops whilst driving, ideally I wait for it to cool then top up to the brim, however if on the move I’ll release the cap a bit and release the pressure that lets the water go back up the max (top of neck). Whilst driving for 350miles at the weekend, I stopped once and released the cap and it was fine. Over this distance it wasn’t much, perhaps a few centimetres including tank neck.

No water gets displaced into the top up tank anymore, and when cool there is no pressure in the header tank, so I’m assuming it's not combustion gases (I haven’t done a sniff test though) as the pressure doesn’t rise enough to open the dalek cap (I’ve changed many times). The water doesn’t drop by too much, so it's usable but assuming it's not sealed that its not operating at the right temperature due to the lack of pressure.

So for my sanity is the likely culprit a high temperature water leak or something else? just can’t quite get my head around the symptoms.

I've got to know the system fairly well over the years, but can’t see any visible signs of a leak hot or cold…….. any ideas?

K

[Dubworth]

Something you've probably already checked, but are your coolant pipes underneath ok? I was chasing down a small mystery leak for a long time...turned out the ends of the original pipes were turning rotten and it was creeping through there.

[kervinmervin]

Yes back to front pipes repacked with stainless steel, as have most others!

K