Cylinder Head Gasket - or something else?

[Spardo]

For a while I have had a warning of low water level signalling on the dash now and again. It rarely needs much water and never overheats. The Citroen dealer has said it needs a new gasket and has quoted €1,500 minimum.

However, a mechanic friend who is laid up with flu at the moment doubts the diagnosis and set me a test to confirm or otherwise.

I put a thin rubber glove on the expansion tank filler and ran the engine on tickover for 50 minutes. He said that if the gasket is blown the glove will inflate with combustion gases. If not, will just receive warm water when it heats up.

I ran the test, the glove didn't inflate.
None of the classic symptons are present. No oil in water, no water in oil, tickover normal, power normal, no black or white smoke, no overheating.

So what have the Citroen garage done to come up with gasket. Pressure test? And would that trump all the rest? On the other hand what do others think is causing the slight water loss problem?

[geoff]

For a while I have had a warning of low water level signalling on the dash now and again. It rarely needs much water and never overheats......

None of the classic symptons are present. No oil in water, no water in oil, tickover normal, power normal, no black or white smoke, no overheating.

How much water and how often ?

Sometimes the coolant reservoir cap fails to seal effectively and can over time allow the water to slowly evaporate.

You may have a very minor weep from a coolant pipe external to the engine.
Cab heaters often have a mnor leak that is evidenced in the footwell area.

From what you describe I'd be sceptical of the dealers diagnosis.

[Spardo]

Thanks Geoff I tried to send a reply but it wouldn't work (Error message) for some reason

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As that seemed to work, I'll try again.

Water loss about an inch from a 1.5 litre water bottle and 3 inches when cold in the morning. Warning first occurred about 2 months ago but now more persistent and about every 800/900 kms.

Coulant cap seems fine, it releases the pressure when I unscrew it slowly.

No visible leaks from pipes in or out of the car but will check again tomorrow.

Could it be a sensor problem? But that wouldn't explain the water loss.

[Gadgetman]

You really need to get the coolant system pressure tested.

This is done by replacing the radiator cap with one that has an air pump and a gauge fitted to it.
Just pump it up a bit and leave it for few minutes. If the pressure drops, you have a leak. Try to stay below 1.4Bar when testing, though, as that's the 'release pressure' on the valve in the radiator cap. Pumping it up to a higher pressure can cause ... issues...

£1500 sounds expensive even for a head gasket replacement...
Did they say explicitly that it was the cylinder head gasket?

[Spardo]

I am in France and the term used was 'joint de culasse' which does translate as cylinder head gasket.

My mechanic friend has suggested putting a thin rubber glove over the filler after removing the cap, securing it and then running the engine for a while. I did it yesterday but just to make sure will try again today. he says if the glove inflates it shows that there is a leak into it of combustion gases, thus a gasket problem. It didn't inflate.

I am going to try something simple tomorrow too. Buy a new pressure cap. If the current one is faulty it might explain both the warning signal and the water loss.

Oh, by the way it was 1,500 euros, not pounds, but still very expensive.

[Gadgetman]

Take a good look at the radiator cap.

I assume it's a black cap with a heavy metal spring?
If it's the same as used on the Mk. I models, there's a 1mm thick gasket on the bottom, the spring is made of a square-section metal, and there's some plastic in the center.
Clean the gasket thoroughly, then put your lips to it and pretend that it's a trumpet and BLOW!
If you can blow through it at all, you can either wear spandex and call yourself 'Captain Trumpet' or the valve is shot...

Another and not as embarrassing way to test it is to rapidly SQEEZE HARD on the top radiator hose(while the cap is in place, of course).
If there's a problem with the radiator cap you should hear the air at the top of the expansion tank escape through the cap.

[Spardo]

Thanks Gadgetman, I'll do all that this afternoon while I'm out there doing all my other tests. Without looking at it first I'm pretty sure that the cap is as you describe.

[trustme]

For a while I have had a warning of low water level signalling on the dash now and again. It rarely needs much water and never overheats. The Citroen dealer has said it needs a new gasket and has quoted €1,500 minimum.

However, a mechanic friend who is laid up with flu at the moment doubts the diagnosis and set me a test to confirm or otherwise.

I put a thin rubber glove on the expansion tank filler and ran the engine on tickover for 50 minutes. He said that if the gasket is blown the glove will inflate with combustion gases. If not, will just receive warm water when it heats up.

I ran the test, the glove didn't inflate.
None of the classic symptons are present. No oil in water, no water in oil, tickover normal, power normal, no black or white smoke, no overheating.

So what have the Citroen garage done to come up with gasket. Pressure test? And would that trump all the rest? On the other hand what do others think is causing the slight water loss problem?

check for damage to heater matrix pipes under the bonnet

[Spardo]

Just been and done the condom/glove test again, and this time I made a better job of sealing it to the filler aperture.

The glove inflated within 5 minutes. I suppose this means that it is the gasket after all so only two things remain. Bite the bullet and take it to Citroen next week and pay the bill, or find someone as good but less expensive.

One final question. Does the fact that all the classic symptoms are not present mean that it is less serious than it might be and that the head may not need to be skimmed, or is that something that should be done in any case?

[Gadgetman]

No, 5 minutes to inflate does NOT mean the head gasket is shot.

That can also happen if there's air trapped anywhere in the system.
(Trapped air means that water can transition into steam, and when that happens, pressure builds.)

Do a proper bleed out of the system to get rid of any trapped air before doing anything else.

Which engine do you have?