2.7Hdi Coupe looses water and gains water pressure

[PietHenning]

Thanks for telling me about activation of v7.55. It is what is available here. I'll look some more.

[addo]

The dash gauge doesn't correlate to what the sensor is "read" to have by the ECU. With Planet or Diagbox you can examine the engine parameters and it may well be the temperature is accurately known by the ECU. It's easy to move the dash gauge needle slightly by pulling it off and pressing back on, but exercise care when prising out the instrument assembly.

[PietHenning]

I took the car to the dealer today after. First thing the mechanic asked was if the fans come on. They will check all of it out.
I will post the result here when they are done.

[PietHenning]

Update:
The dealer did a diagnostic test and all is well. Fan comes on at the right temperature, keeping the coolant at the right temperature. They tested it over 2 days driving it for about 20 km, looking for leaks etc. I took the car back and drove it for 120 km while the temp was OK all the time. After cooling over night it took 1.5 liter of water. I went back to the dealer and the senior mechanic suggested the following:
If the gasket was blown it will push out water much faster than it does and at a rate he will recognize because he saw blown gaskets and how they behave. The car also starts smoothly after cooling, indicating no water on the pistons.
If the thermostat was jammed shut causing the engine side to boil the water will also be pushed out much faster. The symptoms of my car does not match his experience of this problem. Another reason he does not think it is the problem is that the whole radiator is hot - therefore the water passes through it.
He recons the only other place where water can be lost and air be introduced is the Exhaust Gas Recirculation (EGR) Valve Tube. There are two of them. He had one case in his 15 years at Peugeot where there was a leak.
I will now remove then one at a time and pressure test them.
Report will follow.

[Northern_Mike]

I believe you have a head gasket failing I'm sorry to say. I had a C5 2.0HDi with exactly the same symptoms - never overheated, the fans came on, all diagnostics were fine, but it used about a litre of water per 160kms and pressurised the cooling system so badly that I could open it cold in the morning after a drive the evening before and it would spray out.
Radiator and all hoses hot, thermostat fine. The garage initially didn't think the head gasket had failed, but a coolant test, after draining and refilling it showed that there was exhaust gas contamination.

[Peter.N.]

Sadly I would agree with Mike, there are degrees of leakage and it will only blow the water out rapidly or instantaneously if the leak is very bad. I can demonstrate this with a car of my own, I bought a Citroen XM diesel four or five years ago, the first time I used it on a long journey the low water light came on and I had to top it up several times, it had a leaking gasket and was blowing the water out of the overflow.

I loosened the filler cap to allow the pressure to escape and it stopped doing in, in fact I don't think I put any water in it for the last year it was on the road.

Some years ago a bought a Citroen CX diesel, the first time I pushed it up a hill all the lights came on and it virtually emptied the cooling system and yet I had driven it several hundred miles without water loss, it was only when I booted it that the pressure got high enough to expel the water.

Over my car repairing life of about 50 years I have had many head gaskets fail and the symptoms can vary wildly but once the leak starts it will normally get progressively worse - except in the case of my XM.

Peter

[CitroJim]

Sadly, I too agree with Mike and Peter on this. I had the same with a Vauxhall Chavalier many years ago...

[PietHenning]

Thanks Mike, Peter and Jim. I'm afraid you are right, but proving it to the dealer may be a challenge. The engine is under warrenty and I want them to own the problem.
My test results:
My friend and I by-passed the EGR units by removing the water pipes and connecting them to each other. Then we plated the gas exit to close them both. The EGR is closed off and the water does not come near the gas in the heat exchanger. The car behaves the same. To prove that the EGR's are not leaking we plugged one of the water holes and connected a pipe the other. The end of the pipe was put into water. If the exhaust gasses leaked there the pipe would have blown bubbles. None of the EGR's did.
It is holiday season in South Africa now and everything and everybody is closed for Christmas etc. The workshop/dealer opens again in the 2nd week of January. I'll take the car to them then.
I will update again in January. Merry Christmas to all,

[PietHenning]

PS: Is there a way to test the water. The CO2 test we did at idle rpms did not show anything. I was hoping that I can drop something into the water that will react with Co2 or other exhaust gas elements to change the water colour. Testing for co2 under load will be difficult. I'm not sure the workshop will do it. Any suggestions?

[Peter.N.]

There is a test that can be done but I don't think its reliable, I think it's hydrocarbons you are looking for not CO2. I hope you get it sorted out OK.

Peter

[addo]

I would plumb a simple pressure gauge into the cooling system, bleed of air carefully and place it so the gauge could be clearly read by your dash camera.

My petrol V6 Pug has a similar head gasket issue, when pushed hard it builds up quite a lot of pressure and starts to expel coolant.

[Peter.N.]

Good idea

[PietHenning]

Good idea yes. I will do so if the dealer cannot be convinced that the gasket is blown. The pressure will not show more than 1.4 bar because the cap releases at 1.4 bar. I will not try to allow more pressure to see where it goes because I blew my Nissan Patrol radiator which had a wrong cap (replaced by mechanic that worked on my car). It was a costly repair.

[Peter.N.]

Once the engine has come up to temperature, if you release the pressure it should not come up again unless the gasket is leaking, if you see it rise when you accelerate hard the pressure is coming from the leaking gasket if the temperature has not increased.

Peter

[PietHenning]

Thanks Peter, I agree with you, BUT I have to convince the dealer. The dealer holding the warranty is 1400km from me, so the dealer here must convince the the warranty dealer. This will happen in early January when the industry wakes up after summer holiday(South Africa).
My system pressurizes when the engine runs to hot and actually releases pressure at the cap, even after the engine stops. You can hear it. The fact that pressure is released after the engine stops seems to indicate that there is a reservoir or pocket of gas/air somewhere in the engine. If I release the pressure it just builds up again.
BR Piet