Engine: D5: 06 plate V70 D5 Engine oil leaking into coolant

[stoneconservator]

My V70 had started losing/using engine oil (some where around 1 litre in about 2000 miles topped up with about a quarter litre each time) but I couldn't find a leak anywhere until the engine overheated and the pressure realise on the coolant system opened and it turns out the oil had been getting into the coolant. My local servicing garage (not a volvo dealer) had seen similar problems twice before (one in a V70 and one in an XC90 - both diesel) in both these cases the system was flushed and refilled and that seems to have been the end of it. My car has just passed 100,000 and the others were also higher mileage. The local Volvo dealer says they have not come across this problem. Anybody had this issue and are there any suggestions about the cause of the problem? Obviously it would be good to locate the cause to ensure it doesn't occur again.

[Clan]

Originally Posted by stoneconservator

My V70 had started losing/using engine oil (some where around 1 litre in about 2000 miles topped up with about a quarter litre each time) but I couldn't find a leak anywhere until the engine overheated and the pressure realise on the coolant system opened and it turns out the oil had been getting into the coolant. My local servicing garage (not a volvo dealer) had seen similar problems twice before (one in a V70 and one in an XC90 - both diesel) in both these cases the system was flushed and refilled and that seems to have been the end of it. My car has just passed 100,000 and the others were also higher mileage. The local Volvo dealer says they have not come across this problem. Anybody had this issue and are there any suggestions about the cause of the problem? Obviously it would be good to locate the cause to ensure it doesn't occur again.

You really must change the Oil/Water heat exchanger on the back of the sump .. then flush out the system with some sort of emulsifier to get rid of the oil , also all the rubber hoses will need changing otherwise one day in the future one will burst and all your coolant will be gone in the blink of an eye . The rubber absorbs the oil and rots quite quickly .

[Peter D]

You need to have the header tank check for combustion gases in case this is a HG leak. It could be a straight leak of oil into the coolant so no gases as such and the Cooler will need to be bypassed for a while to see if it fills up with some oil and is the cause of the problem. The cooler can be pressure tested with compressed air at the appropriate pressure and a leak test done. Regards Peter

[Brendan W]

My money is on the cooler as well. You may also have coolant in the sump. I would drop the oil as a precaution in addition to the actions on the coolant side and flush the system before refilling.

[Bernard333]

Originally Posted by stoneconservator

(one in a V70 and one in an XC90 - both diesel) in both these cases the system was flushed and refilled and that seems to have been the end of it..

Its not likely to be the end of it. If its the oil heat exchanger and its a small leak pressurising your coolant system get it repaired urgently as its likely to burst completely. I am working on a V70 D5 which has every coolant pipe and the thermostat housing completely blocked with a black/grey gunge, I removed a pint of this stuff from the top radiator hose by pulling a rag through it but its in all the pipes and radiator etc. In my case it may be a failed heat exchanger but not 100% certain, the car starts easy and runs fine and the sump oil looks ok but the engine overheats after 8 miles. I am planning to temporarily fit a unit taken from a petrol V70 provided I can find a way to get the gunge out of the coolant system, its smaller capacity but looks to be the same fixings.

[stoneconservator]

Thanks for the replies. I've been away a few days so couldn't check and reply any sooner. Will take a look at the suggestions about the oil cooler etc. Certainly having cleaned out and replaced the coolant the car is still over heating quite quickly so problem will definitely be more than simply cleaning out the oil/coolant emulsion! All very helpful comments and much appreciated.

[Bernard333]

I can confirm the oil cooler on my V70 D5 had burst, have replaced it with one taken from a T5 which although lower capacity will do for now. As you can see from the photo the thermostat is gunged up so main problem is getting it all out from the engine/radiator/heater matrix/egr etc. The thermostat still opens but the gunge prevents coolant passing through it so the engine was overheating . Fortunately even though the flow rate from sump to coolant system was about 1 litre of oil per 20 minutes it seems to have been all one way so the engine may be ok. If you suspect a leaking oil cooler my advice would be get it sorted urgently before it gets worse. I started another thread on this and will post more photos.

[Brendan W]

I hear that dishwasher tabs are your only man for degunging the coolant system.

[Bernard333]

Yes , looks like the dishwasher tabs are the way to do it, I just dont like the idea of detergent in the water pump but at the moment I cannot see an alternative as just flushing with water is not working.