Water Leak

[kennyfin73]

Have a leak somewhere and bugger if I can find it. Replaced plastic connector below air manifold (was leaking there) and renewed O rings in radiator hose to same connector. All good there now. No evidence of water under car, no oil in water or vice versa and running at normal temp.
Can only think it may be pin hole in radiator or water pump dripping and disappearing when running. No real sign of water anywhere. Head gasket????  >:(

[X5Sport]

How fast is the loss?  Have you checked the pressure cap?  Might be allowing a steady water loss if it can't maintain pressure.

Another thing to try is to pressurise the system when cold and look for leaks.  There are devices you can buy/beg/borrow which go in place of the pressure cap location and allow you to bring the system up to operating pressure without it being hot.

[kennyfin73]

I noticed the pressure cap has only one o ring but there is no evidence of any escape from cap.
Are you thinking there may be a vapour leak at the cap ultimately causing a drop in coolant level. Will get a 2nd O ring tomorrow.

The leak is prob about 100ml per 150 mile maybe. Rough guess!

While we are on the cooling circuit do you know the sizes of the larger water hose O rings, am guessing 38 - 40mm by 4mm.

[Horizon]

[quote="kennyfin73"]
Have a leak somewhere and bugger if I can find it. Replaced plastic connector below air manifold (was leaking there) and renewed O rings in radiator hose to same connector. All good there now. No evidence of water under car, no oil in water or vice versa and running at normal temp.
Can only think it may be pin hole in radiator or water pump dripping and disappearing when running. No real sign of water anywhere. Head gasket????  >:(
[/quote]
Give us a clue, is it a diesel or a petrol, 3.0 or V8. The expansion tank is a usual suspect, it's best to put your car details on your signature to help people in diognosing certain problems.

[kennyfin73]

Its a 2003 3.0D (184hp).

Expansion tank is good, no signs of leakage in that area