Problems With Cooling System?

[theprouk]

Hi,

 

I seem to be having a problem with my 110hp HDi Xsara. I have to top up the coolant frequently and it seems to be leaking out of the top of the expansion tank, through the cap. As soon as the engine is started, water disappears from the tank and it builds up with pressure. When the cap is then taken off, you can hear the pressure released and the water comes back.

 

If the cap is taken off the expansion tank and the engine revved, the water boils over from the expansion tank.

 

I have been told it could be the head gasket, does anyone else know what it could be?

 

Cheers.

[billskipton]

My Xsara is displaying the same sort of symptoms - wondered if you'd solved yours, and what the problem was?

 

Best regards,

Bill.

[185nick]

I'm having exactly the same problem. The cap on the expansion tank works as a release valve, if the pressure builds up too much it will let water out to save the expansion tank from cracking. I took my car to the garage to see if head gasket had gone, this can cause cooling system to become pressurised too much, so worth getting checkecd anyway.

 

It turns out the my thermostat was not opening proeprly and not allowing water to flow around the system, thus the build up in pressure. The cause of the problem could be either of these two things or just simply and air lock in the system, which will also not allow proper flow. Only had the thermostat changed the other day and still having problems, but I think this is due to system not being bled properly after thermostat was changed. Am going to bleed it today will post again to let you know how I get on.

[Jonno]

Quote theprouk"If the cap is taken off the expansion tank and the engine revved, the water boils over from the expansion tank."

 

Have you checked the engine oil lately?? Is it emulsified (creamy couloured) if so it may well point to a head gasket leak between a cylinder and oilway.

If there are a lot of bubbles in the expansion tank it could point towards a head gasket leak between a cylinder and coolant waterway.

If you have been having to top up the expansion tank regularly then there is a problem somewhere. Coolant is obviously being lost and if it is coming out of the expansion tank cap there is some serious overpressuring problems.

I hope its something as simple as a stuck thermostat not allowing proper circulation and not something more serious. What sort of mileage has the vehicle done - not that it should make a lot of difference. I am coming up to 107k on my Xsara HDi?

Any other signs of problems - such as increased coolant temp (more than normal)

[theprouk]

On my car, we ended up taking out the thermostat and the problem still occurred. In my particular case it turned out that it was the head gasket that had failed. :blink:

[PaulCartwright]

the exact same thing happned on my 2.0 petrol C5 i did the same thing you guys did thermostat and did the same what it is you wont believe but it DOES work

 

go to citroen and get a new expansion tank cap (the part you take off to put the coolant in) costs about £3 soled the problem instatly

 

theory is water wont boil in a vachume but if the seal on the cap has gone then there is no seal and it allows the water to boil and when you rev the engine the water pump works harder and pumps more water round the engine and it throws it out the top of the expension tank

 

it does work as i had the same problem on my citroen and it was solved instantly

 

Paul

[Jonno]

theory is water wont boil in a vachume

 

Sorry mate that's wrong.

 

Water will boil very easily in a vacuum and at a much lower temperature than 212deg F (100deg C). It's the opposite that applies. You can exceed 100 degrees without water boiling if it is under pressure. Taking it to extremes we have water at work that is in excess of 500 degrees farenheight and still in liquid state - but it is under 600psi of pressure !!

[185nick]

Well I'm still having problems with mine. Bled the system with engine hot and running, as this was suggested to me. Also bled it cold with tight fitting funnel on expansion tank to raise water level above bleed valves on engine (a lot easier and about a foot of 1 1/4" waste pipe, the white pipe that comes out the bottom of your bathroom sink, works a treat. Just take the expansion tank cap off, jam pipe in hole and fill to the top with water, when you have bled the system just pull the pipe out and let water fall on the floor. The excess water in the expansion tank will blow out when the engine's hot.) I have also changed the expansion tank cap, although not brought from citroen dealer, so not authenticated part, took car back to garage today to have the system pressure tested and tested for carbon monoxide in the coolant, a sign of head gasket failure, both tests came back fine.

 

This is driving me nuts now, have emailed citroen this evening to see if they can shed any light on the matter and trip to citroen dealer tomorrow for expansion tank cap, as you just never know.

[jtonky]

the exact same thing happned on my 2.0 petrol C5 i did the same thing you guys did thermostat and did the same what it is you wont believe but it DOES work

 

go to citroen and get a new expansion tank cap (the part you take off to put the coolant in) costs about £3 soled the problem instatly

 

theory is water wont boil in a vachume but if the seal on the cap has gone then there is no seal and it allows the water to boil and when you rev the engine the water pump works harder and pumps more water round the engine and it throws it out the top of the expension tank

 

it does work as i had the same problem on my citroen and it was solved instantly

 

Paul

---------------

Paul, so doing this solved your problem?

I have the exsact same problem with my 1.4 d ax. i was thinking it was over heating, maybe because the fan was not working, maybe because it was not logging the temp correctly, but indeed if the cap is faulty maybe its not allowing the water to get pumped around correctly. ?

[185nick]

I changed my headgasket a couple of months ago and it solved all my problems, haven't had to top up my coolant at all and it seems to be running better as well. Money well spent!