Burning Coolant...

Xantia2.0 · Unread post by **Xantia2.0** » 04 Oct 2010, 15:57

Yep, the thing all us drivers dread. The day we check our coolant and see it has went from the maximum mark to below the minimum mark in less than a week...

However I don't think it is the Head Gasket as there is no smoke, no noticeable loss of compression, and no oil in the coolant/coolant in the oil. I've looked through the history and in all its 148,000 miles it has never had a new Inlet Manifold Gasket. So I'm guessing a mixture of high millage and old age has perished the gasket.

Is there anything that could have caused the gasket to go ?

P.S. I got the wheel bearing changed

spider · Unread post by **spider** » 04 Oct 2010, 16:42

Congrats on wheel bearing.

Its not leaking out is it ? , radiator probably prime suspect.

Some leaks (tiny pinholes) will only leak when warm and under normal pressure, making the difficult to spot (tell tale antifreeze staining is a good clue)

Probably take it to a nearby garage and get the coolant system pressure tested (they fit a special cap and pressurise the cooling system, leave it a short time and check to see that the pressure has not dropped) , that's certainly the 'easy' method.

Caution: if you have a component that is just 'starting' to fail, it can be made worse by this test.

I thought about using the exhaust analyser to sniff the coolant vapour but not too sure if this will work on a diesel actually. EDIT... Just noticed yours is petrol. Basically if there's any HC present in the vapour (do NOT let the probe have a drink!) then the h/g is probably failing.

Alternative is to have a block tester (fits in coolant bottle and fluid inside tester changes colour if gasses are present) although I've never really found these terribly reliable.

Personally, I would pressure test the coolant system first.

At least on a petrol the hoses around the back are (relatively) easy to get at, I remember on the XUD9 there was a loop at the lower end and it was horrible to fix due to no space (a bit like where the early XUD's had the fuel heater, but worse)

Xantia2.0 · Unread post by **Xantia2.0** » 04 Oct 2010, 17:06

It's not a leak as I've given the rad and hoses a good check. I am also sure it is the gasket as after giving the engine a good rev there is coolant sitting in the tail pipe and a green residue as well.

spider · Unread post by **spider** » 04 Oct 2010, 17:11

Still worth pressure testing.

If its actually in the exhaust ( ! ) , there's a chance of a cracked head / block

, not really sure how likely that is though.

Xaccers · Unread post by **Xaccers** » 04 Oct 2010, 17:26

Check under the front foot well carpets for wet patches.

spider · Unread post by **spider** » 04 Oct 2010, 17:53

Xac wrote:Check under the front foot well carpets for wet patches.

I thought about that too, but figured if it was losing a litre or so it would be really bad inside and smell if not.

DickieG · Unread post by **DickieG** » 04 Oct 2010, 18:06

What about the pressure cap? Invariably forgotten but often the cause in such cases.