C5 2.2 HDI Possible Head Gasket Failure

[acrowot]

My Grandson has a C5 2.2 Hdi that is now overheatig, these are the symptoms. He has for some time been losing water and has been topping it up with just water, somtimes it would be quite a few weeks between having to refill and sometimes quite frequently, during the cold spell he did not use it for a few days and when he did it overheated and lost water. I had a look and found that someone had done a repair on the top hose this was covered up with a sort of protectve hose and was not easy to see, it was a sort of rubber solution covered with a bandage and this hose. What I think happened was that the water had frozen due to the cold weather causing a build up of pressure this pressure found the weakest point to escape from but when the engine cooled down this repair resealed itself. Anyway I replaced the hose with a new one and installed the Anti Freeze and bled the system, it will start and tickover for more or less as long as you want with no apparant problems but a run on the motorway results in overheating and the Stop Light illuminating. At this point there is no water loss but the rad is completely cold whereas before setting off the rad is at normal operating temp. , this cooling system is sealed it has 2 pipes coming from the header tank, one feedin the rad and the other goes to the thermostat housing and this second pipe under the overheating condition has the water rushing through it into the thermostat housing, I think this is stopping the normal operation of the cooling system and preventing circulation through the Rad., there is no water loss once the engine has cooled, I have also removed the thermostat and rebled has not helped. After the engine has cooled down and restarted normal circulation takes place, What do you experts make of this, Head Gasket or Air Lock, or something else.

[myglaren]

This has unsettling similarities to the problems experienced by boristhespie.
Worth a look through!

[cachaciero]

Unfortunately I can't find at the mo a water flow schematic. However taking what you say at face value I would make the following observations:-
If you have, presumably hot water rushing from the header tank into the thermostat housing this would imply that the pressure in the thermostat housing is less than the header tank so where is this hot water coming from and how is it being pressurised the only other pipe being connected to the top of the rad which appears to be full of cold water or maybe no water.

If I assume that what you really meant was hot water rushing FROM the thermostat housing TO the header tank that might make more sense in that if the thermostat was closed then there would bet a trickle flow through the header tank into the rad which may well not get too hot, ultimately the pressure in the system would cause the pressure cap to blow so loosing coolant.

It would seem to indicate a stuck thermostat but you say that you have run without a thermostat do you still get water flow into the header tank from the thermostat housing?.

If the head gasket or the head was cracked I would expect to see water and gas in the header tank even at idle i.e the system will pressurise very quickly far quicker than any rise in water temp.

After the motorway run and getting an overheat you say "that there is no water loss but the rad is cold" how do you know there is no water loss? I ask because an empty rad will likely be very cool / cold. The fact that there may still be water in the header tank is not an indication that water has not been lost.

I do wonder if there is a partial blockage at the bottom end of the rad, or even the rad itself, this might explain why the system appears o.k at idle with a low cooling demand a trickle of water might be enough to keep the engine cool enough but at M/Way speeds??? .

I think I might be inclined to take the thermostat out disconnect the bottom and top rad pipes and back flush checking that you really can get a good flow of water through the engine, repeat for the rad.

Water pump failure also comes to mind although I cannot envisage a failure of the pump which would allow it to pump at low revs but not high, of course if there is enough convection flow through the system to keep the engine cool at idle then a non pumping pump may not be noticable under idle conditions but this is just speculation (rambling some may say

I would also caution that :-

it is very bad news in my experience to run a diesel to overheat conditions a cracked head is just as likely as a failed head gasket.

Running these cars with less than the recommended amount of antifreeze / inhibitors is asking for leaking heater / radiator matrixes they are all made of paper thin crap ally which will corrode and create pin hole leaks at the drop of a hat without inhibitors.

cachaciero

[acrowot]

Hi cachaciero, thanks for your input, the water flow is FROM the header tank to the thermostat housing. There is now no thermostat in the housing and there is no water loss. My reasoning is that the system is becoming pressurised ( there is no pressre cap on this model ) it seems that that if there is too much pressure then the water is pressured into the thermostat housing, I can see the water travelling to the thermostat, I do not know if the water is hot or cold, I also do not know if the water in the header tank is hot or cold I will have another look, it seems as if at this point there is only cold water circulating through the rad into the header tank on to the thermostat housing and back to the rad, it seems at this point that the rad is excluded from the cooling cycle. What did use to happen with the water loss was that the wate was only lost at the end of a journey when the engine was swithed off, a short while later water would be seen to be flowing out of the top hose ( this did not always happen ). On taking off the top hose all seemed to be OK but eventually after taking off the hose after the temp hit the roof and more closeely examining the hose ( after cutting off the protective stocking on it ) it became evident that some previous owner or garage had done a repair on it, it had been repaired with a sort of rubber solution that seemed to reseal when it
cooled down. I think that it all came to a head because of the lack of antifreeze in the car and the fact that the water had frozen. It now only needs a 4 mile motorway run for the seious overheat to take place, the temp gauge remains normal on slow speed town type runs. It had never overheated with the original top hose repair no matter what type or how long the journey was, it would just come up with low water level usually on first start up as the water had been ejected on previous shut down.

[Simon99]

Had a Mondeo recently where the plastic impeller (water wheel) had freed itself from the main body of the water pump so was not rotating while engine was running. Don't know if C5's use plastic impellers but apparently common fault with mondeos. Showed very similar symptoms. Obviously, to check this would involve removal of timing belt.

[acrowot]

Had a Non-Citroen recently where the plastic impeller (water wheel) had freed itself from the main body of the water pump so was not rotating while engine was running. Don't know if C5's use plastic impellers but apparently common fault with mondeos. Showed very similar symptoms. Obviously, to check this would involve removal of timing belt.

Thanks Simon99, I seem to remember something similar on a Singer Vogue I had many years ago, it also made the heater very poor, this C5 has allegedly had it's cambelt and all associated bits changed some 20000 miles ago but who knows, it is something to bare in mind.

[cachaciero]

Had a Non-Citroen recently where the plastic impeller (water wheel) had freed itself from the main body of the water pump so was not rotating while engine was running. Don't know if C5's use plastic impellers but apparently common fault with mondeos. Showed very similar symptoms. Obviously, to check this would involve removal of timing belt.

Interesting that would be a prime candidate to explain a means by which a pump may pump at low speed but not at higher speed. If the impeller is not tight on the shaft then it would be logical to expect it to slip more at higher loads aka speed.

cachaciero.

[cachaciero]

Right have now found my 2.2 water flow diagram and......
it does not change my opinion that there is either a blockage / restriction on the lower return from rad or a pump failure given that simon99 says that this is common on Mondeo's and they use the same engines it becomes a much more likely candidate.

cachaciero

[acrowot]

Right have now found my 2.2 water flow diagram and......
it does not change my opinion that there is either a blockage / restriction on the lower return from rad or a pump failure given that simon99 says that this is common on Non-Citroen's and they use the same engines it becomes a much more likely candidate.

cachaciero

Thanks cachaciero, I do not think there is a blockage in the bottom of the rad, before the overheat the engine behaved normally except for the occasional water loss from the top hose which had been botched up. I think that the water loss happened when the engine was hot and switched off the top hose would have got hotter as the water was no longer ciculating and hot water rises, I think this caused the rubber type solution to soften and allow the water to escape, as the engine cooled the rubber solution solidified and we were then just left with a shortage of water. The result of adding just water diluted the antifreeze. The car had not been used for about a week during one of the very cold spells during the winter, I think the water froze in the engine causing the overheat, the car had only travelled about 2 miles down the motorway. This theory leads me to believe that maybe simon 99 is correct, if the water pump impeller was surronnded with frozen water and the timing belt turned the pump shaft with the impeller trapped then maybe the shaft turned inside the impeller. I ran the engine on tickover today for about 90 mins, it behaved as it should no overheat, no pressure build up no bubbles in header tank either on tickover or while reving the engine, no loss of water everything nice and hot including all of the rad. The heater always works as it should even when it overheated and the subsequent overheat on testing.

[spider]

Regarding the water pump impeller (sp?) , that was my thought too, as it will circulate in a vague fashion anyway.

Some old TU (1.1 / 1.4 petrol engines) used to suffer with rotted / broken impeller's too...

I'd be tempted to change it to be honest or take it out and confirm at least, then run with no thermostat again (to eliminate that)

While its in bits, its well worth flushing everything out too, just to confirm nothing is blocked (a foreign body possibly, think of something that has accidentally been dropped into the bottle or into an open hose and is moving around.

[CitroJim]

Some old TU (1.1 / 1.4 petrol engines) used to suffer with rotted / broken impeller's too...

Looking at the pump I took out of Robyn's 206 (1.4 TU) I can well understand that. Looks almost as if they suffer from a touch of cavitation. There's some interesting patterns on the impeller..

[acrowot]

Had a Mondeo recently where the plastic impeller (water wheel) had freed itself from the main body of the water pump so was not rotating while engine was running. Don't know if C5's use plastic impellers but apparently common fault with mondeos. Showed very similar symptoms. Obviously, to check this would involve removal of timing belt.

Spot on there Simon, just got round to taking the water pump out and it is exactly as you describe, thanks for your input, the car was my Grandson's but it is now mine and he has my Xantia, looking forward to driving it, it is a very nice ride.