C5 HDI Water Pressure Problems!!!

slim123 · Post by **slim123** » 26 Nov 2006, 17:16

Not having much to do with the HDI engines, a mate just popped over and asked if I would have a look at his C5 HDI, I didnt look but I think it's a 2.2.

The problem is that the water is pressurising and the hoses are rock solid, he says that it dumped the water out, he topped it up and it drove back home 50 miles with no problems. But looking at the header tank he has constant bubbling and a serious pressure problem.

Also the rad fan dosent seem to come on at all, although the temp gauge was not in the red!

Now, if it was a 1.9 Xantia I would say head gasket and check the head, but he says that it did this about a year ago whilst under warranty, he took it into Citroen and they could find nuffin wrong, the car has been fine since!

Questions are, does the HDI engine have the same reputation for head problems as the older Xantia / BX engines?

How is the fan controlled? is it via the Bitron sensor (as in the Xantia) ? if so where is the Bitron sensor ? or any other sensor for the rad fan.

Any clues would be helpfull.

Regards
Slim

jeremy · Post by **jeremy** » 26 Nov 2006, 18:09

If it gets hot and boils the pressure will rise to something huge BUT when it cools the steam will condense and the pressure will return to zero or close.

If the pressure remains high when its cold - then it means that additional gas has been introduced into the system from somewhere - and about the only place is through the cylinder head gasket.

citronut · Post by **citronut** » 26 Nov 2006, 18:43

first thing i would do is thoughly bleed the system,and get the fan/s working,but before anything when stone cold remove the cap and get someone to cranck it over whilst you look to see if the coolant erupts or just any gas come up through the coolant,as you probably know anyway
regards malcolm

slim123 · Post by **slim123** » 26 Nov 2006, 20:00

Hi Malcolm.

Yes thats what I told him to do, let it cool down, bleed the system through, then run it with the cap off.

Next thing is, where is the fan switch??

Anybody know?

Regards
Slim

wheeler · Post by **wheeler** » 26 Nov 2006, 23:18

the fan is controlled by the engine ECU from the info it gets from the green temp sensor in the thermostat housing.if the sensor fails it should put the fan on at full speed (just like the bitron setup) so i dont reckon there is a problem with the sensor.

slim123 · Post by **slim123** » 27 Nov 2006, 18:39

Well, new events today.

This morning whilst the engine was stone cold, he drained off all the water and refilled slowly with an anti-freeze mix, making sure that all air was out through the bleed points. He then started the car and no apparent problems, but only ran for a few mins.

Later he comes out to the car to find a puddle of anti-freeze / water under the car, now this appears to be from the water pump, (dripping from the cam belt cover) so he is gonna get it changed along with cambelt etc.

My money is still on the head gasket, as a duff water pump has never caused pressure in my book, or would the air ingress cause it??

No doubt, time will tell.

Regards
Slim.

citronut · Post by **citronut** » 27 Nov 2006, 18:47

unlikly but what might have acured is the pump has been leaking so level has gone down and has been topped up without bleeding the system,hence trapped air maybe,to check for head gasket just crank it over stone cold with the cap off to see if the coolant eruppts or gasses up,you can only do this check with the engine stone cold
regards malcolm