Oil in Coolant?

[Hannya92]

So I got the car back with the oil cooler replaced and flush done, now coolant is clear pink and I have to drive it for a while to see if it stays this way.

In the garage the guy told me he is not able to see if the oil in the coolant was caused by the oil cooler as the leak would be inside and not visible.

Car drives fine as it was before so I can't really notice any differences beside the coolant colour.

Fingers crossed guys!

[PaulC5]

If you kept the old cooler it might be possible to pressure test it to see if it leaks. Anyway, hopefully the fault has been fixed and the coolant will remain clean.

Probably worth while finding out what make of coolant has been used in case you need to top it up, coolant from Citroen is usually blue so likely a different brand.

[Hannya92]

I didn't got to keep the old cooler, I did 200km so far all good.

The only thing I noticed was that the temperature of the coolant changes goes up to 7 then might go back to 5 before it stays at 6 then sometimes might go up or down again but always go back to 6 after a couple seconds, can anyone please confirm if this is normal or do I have to look at a new sensor?

[PaulC5]

If it did not do this before then there could be some air still to bleed out. If you have a code reader with live data see what the temperatures are.

[Hannya92]

SO I did the test this morning, after having the par parked the whole night I opened the coolant cap and there was back pressure leading some of the liquid to spill out.

Then I drove the car and checked the temperature with the reader - went up to 83C no problem then it went down to 75C depending on the the speed it would go up again to 83C or drop down to 75C but at 90km/h in 6st gear it would stay at 75C with 10degrees outside temperature.

Looks like i have the thermostat stuck opened...

[Gibbo2286]

SO I did the test this morning, after having the par parked the whole night I opened the coolant cap and there was back pressure leading some of the liquid to spill out.

Then I drove the car and checked the temperature with the reader - went up to 83C no problem then it went down to 75C depending on the the speed it would go up again to 83C or drop down to 75C but at 90km/h in 6st gear it would stay at 75C with 10degrees outside temperature.

Looks like i have the thermostat stuck opened...

Stuck open rarely happens with wax pallet thermostats they usually lose the wax and stick shut.

[Hannya92]

maybe somebody can confirm but i dont believe the correct operating temperature is 75 degrees

Also the pressure on the coolant after the car has been parked for over 12h... do I have to look at testing the head gasket?

[Gibbo2286]

I think maybe you do. Although as someone else suggested check the the bleed out of air is complete.

[Hannya92]

i did over 200km since the change of the oil cooler and the flush of the system - no performance issues so far just the variation of coolant temp ( 75c to 83c) i assume there was suppose to be no gas build up on the coolant at this stage

[xantia_v6]

75° seems too low, but check the temperature of the top radiator hose with an infrared thermometer, on some engines the temperature sensor reads low because it sees a portion of cold water from the bottom radiator hose.

[Hannya92]

I don't have one of those but I'll figure something out, I assume it's a bad thermostat, I've looked and they seemed to open at 83C so that would be the minimum temperature when running I suppose.

[myglaren]

I don't have one of those but I'll figure something out, I assume it's a bad thermostat, I've looked and they seemed to open at 83C so that would be the minimum temperature when running I suppose.

Lidl have them for a tenner and there are other similarly inexpensive sources.
I would buy one but then never use it.

[Paul-R]

I would buy one but then never use it.

I have one which I use mostly in the kitchen to check the oil temperatures when I do twice cooked chips.

[MattBLancs]

could one of the causes be the oil cooler?

My understanding is the oil "cooler" (which is an oil-coolant heat exchanger) can fail but tends to be very significant volumes of oil into the coolant (and header tank full of black muck rather than your frothy cappuccino )

Potential you've only "early stages" of cooler failure but otherwise head gasket is possible.

How is coolant temperature behaving (not running hot?) no experience of 1.6 HDi in a C5 but other applications it has normal running temperature of 90° C on the gauge.
How is engine performance - hard to say if you've not had it long?
How are coolant hoses? (Not rock hard as under significant pressure?)

Is is pushing any coolant out of the expansion tank?

[Hannya92]

The oil cooler has been replaced already

How is coolant temperature behaving (not running hot?) ive checked with OBD scanner it foes up to 83c then it might drop to 75c depending on the journey but usually stays between 79/80C
How is engine performance - hard to say if you've not had it long? my wife as a 1.6 and this issue is oin my 2.0hdi - the 2.0hdi performs way better and its responsive so for now i rule out performance issues
How are coolant hoses? (Not rock hard as under significant pressure?) ill check this tonight

Is is pushing any coolant out of the expansion tank? no, but if the car sits for >12h and i open the cap (slowly) i get this big burp of coolant out, like there's some build up pressure stuck there that has nowhere to escape