Coolant loss

[cla5h]

Car has been losing coolant for some time - initially found to be a burst rad which was changed a year ago.
Later found to be losing it from a loose hose, so tightened clip.

However still losing it now - drops from Min to near bottom of expansion tank within 3 fuel fill-ups.

Have run car till fan kicks in, and can't see anything coming out. Have put 22psi into system, and no obvious leaks (although left it pressurised for up to an hour, and when I disconnected airline, level looked a bit lower than when I started.)
Also jacked either end to see if anything would flow from front or rear -still nothing.

Have now tightened all jubilee clips that I could get access to, just in case.

Small amount of mayo in oil filler cap, which I've previously put down to condensation from car lying unused for week or two at a time.

Anyone got any opinions?

[Shug]

It might just settle at that level. Leave it to see how far it drops (obviously without letting it go so low it's out of the expansion bottle)

Mine has always settled low - over two different engines.

Take it you've changed the cap on the tank?

[cla5h]

Yep, cap's been changed twice in less than two years.

Previously, I've let it get so low that I can only just see it at the top of the hose entering the bottom of the header tank - didn't want to let it go any lower.

[Shug]

Could be a slight inlet manifold gasket leak?

[tenkfeet]

Have you bled it fully after the leak . If there is air trapped it will expand and hoof it out . When I took the cap off VERY CAREFULLY when it was hot to top up the fluid the coolant would rush in and rise to near the top of the tank . Bleeding properly and leaving the cap off when it was warming up solved it.

[robin]

The dynamics of the coolant level will be affected by the presence of air. Extra air will not make the system pressure increase - quite the opposite - the air compresses nicely, so the more air you have, the less pressure is created by the incompressible coolant expanding (think about it like doubling the volume of the expansion tank, but leaving the volume of coolant the same; there will obviously be less pressure in the expansion tank when hot).

If there is extra air somewhere else in the system, it will compress and the coolant level in the tank might even drop rather than rise as the car heats up (in fact this is a sure sign of air in the system).

I very much doubt that extra air will cause coolant loss (but coolant loss can cause extra gas, in the case of HGF and also with some types of leak, coolant goes out as it heats up, air comes in as it cools down).

Inlet manifold gasket or head gasket are the most likely causes. On early S1 could also be pinhole in coolant rail in drivers side chassis, but this was fixed sometime in 98 IIRC.

Cheers,
Robin

[cla5h]

Coolant rises normally when hot, so probably not air in system.
Never had any issues with temp.

Car's a S2 (52 111) so shouldn't be affected by coolant rail issue.

Re: Inlet manifold gasket, previous posts say a symptom would be coolant getting into spark plug chambers. Plugs were changed at service 6 weeks ago, and no mention was made of anything untoward (granted, I didn't ask.)
Would enough time have elapsed for the new plugs to show signs?

Re: HGF - may seek out a HC sniffer. If this was the case, would it have been noticeable in the oil when it was changed at service?

[robin]

Doubt anything would be noticed during servicing - depends on who's doing it and whether or not they've been primed to look for it.

The coolant doesn't get into the spark plug bores, it gets into the combustion chamber and steam cleans the plugs ... so if one plug is shiny and the others are the normal browny/grey colour then I would say you have coolant->chamber leak - either HGF or inlet manifold gasket. After 6 weeks and a litre or two of coolant, you might tell the difference if you popped the spark plugs out again.

Cheers,
Robin

[steve_weegie]

Re: HGF - may seek out a HC sniffer. If this was the case, would it have been noticeable in the oil when it was changed at service?

There's a couple of different kind of HGF. Oil to water is generally the result of an elastomer seal blowing and gives you the mayo in the oil & expansion tank. Combustion gas to coolant is the one that the sniffer test looks for & doesnt necessarily give you mayo, but will give you air in the coolant system & the resultant temperature spikes. Gas to coolant is normally the result of liner height problems, fire ring failure on the gasket, or a mixed bag of other head problems....

You can pick up a sniffer online for about 20 quid, or you're welcome to borrow mine

[Matelotman]

My inlet manifold gasket leak was a visible drip which left a small wet patch in the dirt on the inside of the undertray.

[Rich H]

Heater matrix weep? Any odd smells in the cabin?
Does it loose coolant when stationary or only when moving/engine running?

[cla5h]

Familiar with the smell of anti-freeze in the cabin from when the rad was burst, so no.

As to stationary/running- I'd say the latter only, although difficult to judge.

Never found any wet patches or stains on undertrays.

[whaleys]

My coolant level changed after I had the remote thermostat fitted. I was told that changes to the coolant system can change levels and the relocation of the thermostat was probably what caused it. I was a bit paranoid about it for a while but it's happy level seems to be about 1 cm below the min level when cold and at the min level when hot.

G