Odd cooling system problem.

[Aunt Trumpet]

When checking my wifes Bongo header tank the other day it was empty so I filled it back to the max mark. It took about a kettle full.

I've checked it at different intervals since and every time it was empty, however it only ever takes about the same amount of water. This leads me to conclude that its losing water but only until a certain level then stops. The temperature gauge never says anything different but normal.

Any ideas what could be going on here?

Any help much appreciated.

[francophile1947]

You've obviously got a leak from somewhere. Have you checked the hoses in the engine compartment and underneath?
The temperature gauge is useless, so you can't rely on that - by the time the gauge shows anything, the engine is often ruined.
If you are having to put a kettle of water in, the header tank must be empty. You must bleed the system before using the car, because there will almost certainly be air in the system. I assume, as you make no mention of overheating, that she is only doing short trips.
Is there any smoke/steam from the exhaust or signs of water in the oil?

[Aunt Trumpet]

Yes, it is only doing short trips with the occsional long one. It doesn't appear to be overheating or losing water onto the drive when stopped. No signs of water in the oil as I've just done an oil change.The header tank is emptying, but how come it is a certain amount? If I had a leak would it not keep leaking until I was completely out?

[scanner]

Yes, it is only doing short trips with the occsional long one. It doesn't appear to be overheating or losing water onto the drive when stopped. No signs of water in the oil as I've just done an oil change.The header tank is emptying, but how come it is a certain amount? If I had a leak would it not keep leaking until I was completely out?

But not if as you say the leak is at a certain level at or near the header tank.

Is one of the hoses into/out of the tank loose so the joint is leaking?

[mikexgough]

there could be a pin hole leak or a weep somewhere, could be in a metal pipe or even a hose........ might be small enough not to see, I had a radiator seam weep a week or so ago, I changed the radiator and checked all the pipes and hoses while there and changed the coolant, via my homebrew method and all is well in the world

[Triple/R]

I'm certainly no expert----could it be the actual header tank,then when it gets to that level it stops leaking???

[Aunt Trumpet]

I'm certainly no expert----could it be the actual header tank,then when it gets to that level it stops leaking???

mmm, the problem is it empties the tank fully.

Think i'll have to fill it up, keep the engine running and have a good look around and underneath.