If the passenger floor is wet, 99% ceratin your heater matrix is leaking.
It's a remove dashboard job to replace it. As a bodge try blaning off the feeder hoses. Will stop leak but no heater...
madf
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If it had lost 1.5 litres though the heater matrix you would know about it - the car would stink, all the windows would be steamed up, the windscreen would be all greasy, and probably steam would be coming out of the vents! Apart from the headgasket, the favourite place to leak on these is the bottom of the radiator, or the water pump intake hose on the back of the engine. Check underneath with and without the engine running - a leak of that size should be easily spotted. If it is the headgasket, then expect the symptoms to include pressure remanining in the system when it's cold, pressure building quickly when the engine is started, bubbles in the coolant header tank (although this is easily confused on these engines as they have a deaerator in the rad neck).
I would suspect the head gasket, but there are other (cheaper!) possibilities to examine first before ripping the head off.
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RichardW
Is it illogical? It must be Citroen....
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The way I was taught to test for head gasket faults was to place the overflow pipe into a container small enough to fit where ever its to be fitted, and then take the car for a run or whatever as you've done recently testing how much water you've used and note if any water of a large amount has filled the boltle. If it has, then your gasket is on its way out.
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i have both pressure remaining in the water system when the engine is cold and pressure in the top water hose after a run so im pretty sure it's the headgasket also im sure theres a detiriation in the performance and mpg is down aswell so guess it's time for a top end rebuild
cheers
chris
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There should be *some* pressure in your colant hoses when the engine has been running for a while. The pressure cap fitted to your coolant reservoir ensures this pressurisation, and the cooling system would not work properly without it.
However, if you have excessive pressure, that can point to a head gasket failure. Typically, using a pressure gauge, the pressure will rise and fall as you rev the engine if the gasket has failed, whereas the pressure in a car with a good head gasket remains more constant.
Also, if the head gasket has failed, then the coolant system can depressurise, via the leak, when the engine is left to stand. As you say that you have pressure remaining in a cold system, I would check more carefully before lifting the head off.
Another reliable way to check for head gasket failure is to pass the sniffer of an exhaust gas analyzer over the mouth of your coolant reservoir with the engine running. Any increase in HC means that exhaust gases are in your coolant, therefore your head gasket has failed. In extreme cases, the bubbles of exhaust gas may be visible.
Your coolant loss may also be the result of a leak that you haven't found, or the result of coolant loss if the engine boils over.
Number_Cruncher
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You will always have pressure while the engine is running, this will be to what ever the pressure cap is set at. This why I said to fit a container and see how much coolant enters to determine whether the gasket has gone. If the container remains empty and then I don't think the gasket has gone.
The reason the system is pressurised by the cap is raise the boiling point of the coolant. Pressure caps normally blow off at approx. 14lbs/sqin.
But if the heater is leaking, and if your car has a high mileage of approx 70/80k plus, then its expected. Its common for Pugs and Cits of high mileage and if the coolant has not been renewed or if the incorrect type used. This due to the acid levels that build up in the coolant and corrode's the element.
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Hi autumnboy,
I think there are other cooling system faults that would cause coolant to overflow. If the coolant boils for any reason, then you may expect to find some ejected from the reservoir.
Possible faults that could give rise to boiling over include, among many others;
thermostat blocked shut
water pump impellor broken
cooling jackets silted up
radiator silted up
airlocks in the cooling system
pressure cap leaking
radiator fan switch inoperative
I'm sure there are more!
Just to be sure, I don't doubt, or envy! :-), your working knowledge of French cars in any way, I only intend to broaden the list of possible causes for the fault given by the original poster, and give suggestions of other items to check before he removes his cylinder head.
Number_Cruncher
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in all honesty im probably going to have the head of anyway as the car has done 117k and the service history really isn't good enough to satisfy me and im not totally happy with the running of the engine so for £100 in parts i feel comfortable enough taking the head off and rebuilding it and replacing cambelt/water pump/head gasket while im on then seeing how it runs after i know everythings been taken apart and reset properly i think a weekend and the aforementioned cost are justifiable for the peace of mind it will bring, anybody got any hints or tips for taking off/rebuilding the head on this engine?
cheers
chris
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Knowing these engines pretty well, I have no doubt your headgasket has gone.... I've had the head off a BX TD for the same reason. It's an awful awful job! How's the clutch? If at all suspect, or it's not been changed, then bite the bullet and pull the engine out and do the head and the clutch at the same time - it will be easier in the long run!
The job is very awkward - there's no room, and you can't see half the fastenings for things like the inlet manifold etc.
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RichardW
Is it illogical? It must be Citroen....
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Richard,
Good luck to the original poster in his work, but I have a question about the diagnosis technique for you.
Above, you say that an expected symptom of head gasket failure is pressure remaining in the cooling system when cold. I don't understand, please can you explain it to me.
I would expect an intact cooling system to maintain some pressure. I would expect a breached cooling system, perhaps with a failed head gasket, to lose pressure rapidly, via the leak.
Is there some Gallic peculiarity which is confusing me?
Number_Cruncher
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I think what Richard means is that in an intact cooling system, the pressure when cold should be zero and rising when hot and returning to zero when cool again. With a HG failure, excess pressure is forced into the system via the leak, resulting in a higher pressure than an intact system. Then, when the system cools, it returns to the zero pressure mentioned above, but with the added exhaust gas pressure remaining.
The exhaust gas pressure will remain as it is forced through a tiny hole under cylinder pressure (high), and cannot return through the same hole when the engine is switched off.This is a pretty sure way of detecting a failed HG.
At least thats how i understand it...
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The remaining pressure may be peculiar to these engines, but probably would effect all diesels with the sort of minor leaks these engines tend to start with. Under normal operation, you open the rad cap (cold) and there is no pressure in the system. As the engine warms up, the air and water try to expand and the pressure rises - not to the point where the relief valve in the rad cap lifts though - as the engine cools down, the gas and water contract again, and the volume is the same as last time you . However, factor in a small headgasket leak. This leaks combustion gas into the cooling system. When the engine is shut down, there is not enough pressure to drive the water the other way (cooling system - cylinder). So, from a cold no pressure start, gas leaks into the cooling system and rapidly pressurises it. The rad cap will now simmer at the relief pressure, as it relieves the gas being forced past the head gasket. When you turn the engine off, there is some reduction in the pressure due to it cooling down, but a goodly amount remains due to all the extra air forced into the system. This results in a noticeable hiss when removing the cap, even when the engine is cold. My BX did this for 70,000 miles before it got bad enough for me to do the gasket (mostly becuase I didn't know what was going on / didn't want to contemplate taking the head off!) The BX used a bit of water, but only about 1 pint every 20,000 miles, until the end when it suddenly started using a lot more. I am not sure if the water was finally going out the exhaust if it was just being blown out of the rad cap. Given it was getting difficult to start by the time I got it in the garage, I suspect both were happening.
It's probably not the head gasket leaking per-se that kills these engines, but rather the gradual loss of water leading to inadequate cooling that then causes it to overheat and warp the head (these heads seem to warp if the sun shines on them too much...!)
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RichardW
Is it illogical? It must be Citroen....
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>>It's probably not the head gasket leaking per-se that kills these engines, but rather the gradual loss of water leading to inadequate cooling that then causes it to overheat and warp the head
I think you are spot on there Richard. I really don't believe these engines have an inbuilt tendency to blow gaskets, but often the system will lose coolant one way or another (often out of the cardboard radiators) and this causes the symptoms you describe.
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Ah, that makes it much clearer, thanks Richard and P2501 for your answers.
I was thinking that surely a leak is a leak, not a one way valve, but I have seen cars which don't start making my pressure gauge yo-yo with revving the engine until they are quite hot - so, the idea of a leak being open while the engine is running, and closing as the engine cools down (and, of course, the arguments about the high pressure in the cylinder compared with the lower relieved pressure in the cooling system), is perhaps the right one to explain this.
Thanks again,
Number_Cruncher
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