Engine running cool, oil in water
 

Hi guys. For a couple of weeks I've noticed the car has been running cooler than usual - temp gauge usually sits at half way mark but recently has been a couple of notches below. Yesterday on the drive to work it barely got past the quarter mark. I checked the water level and the expansion tank was almost empty (no warning light which was strange, too). Filled it up and noticed oil spots in the water - never a good sign.

I checked the oil level and that was low, too. I topped this up a few weeks ago so this isn't normal, either. Today I ran the car with the expansion tank cap off and there were no bubbles and no smell of gasses. There's a little bit of gunk of the oil filler cap but not what I'd call abnormal and none in the oil filler area. Diptick looks clean with no obvious signs of water. Engine is running fine and gearbox changing ok so my question is: Head gasket or radiator oil cooler?

I'm inclined to think it's the oil cooler but the engine temp thing has got me questioning myself. Surely if it was head gasket it would overheat rather than run too cool? Could oil in the water affect the thermostat working properly or is it just as likely to be a separate fault?

Any input is gratefully accepted.
Car is a 2004 C70 2.0 turbo auto convertible.

You need a new coolant thermostat and also a new oil cooler on the sump ,
and a thorough cooling system flush out with an emulsifier . You may get away with the hoses if the oil has not been in there long , but the hot oil does soak into the rubber hoses and eventually ruins them and they burst . A full set of hoses will cost around £300 ! The biggest part of this job is the clean up .

Yeah, that's what I thought. Oil hasn't been in the system long as there was none there last time I checked a week or so ago. I'll give that a bash first and see how it goes. Seems like the cheapest option :teeth_smile:

Cheers!

As above - H/G failure is very rare on these unless they've been properly cooked by running with bad overheating. Beware the low temperature reading, this could be due to the coolant level being below that of the sensor, it could still be overheating.

Re. cleaning the system out, a good trick that definitely works is to rebuild the system, then run it for a few miles with a mixture of clean water and clothes washing liquid in the system, this is pretty good at dissolving the oily residues and leaves it a lot cleaner. You may choose to drain this and do it again, with a final drain/refill of the correct coolant antifreeze mixture.

I'd recommend fixing this pronto, and don't run it any more until sorted.

Don't worry, the car is definitely off the road until it's fixed. I've had the same thing happen to a Corsa I had once so I know what I'm up against with flushing the system. I'm sort of relieved it's just the oil cooler and not the Rad or HG :teeth_smile:

Just a quick update on this to say after changing oil cooler and thermostat everything is fine.

Apart from one of my back springs snapping on the way home from work tonight :angry_smile::mad:

Alby

It may warm your heart to know you are not alone

After 11 months i finally sorted out all the tools and kit to change the timing belt on my Saffy R. Drove to my girlfriends put her on stands to discover some tick turd had obliterated the timing marks on the cams and replaced them with 2 marks, one of which cannot be in the correct position !!

Had a chat with John at Volvo Services in Wickford and agreed in the circs I would get him to do it. He then confirms my suspicion that the offside lower engine mount is completely shot and of course all parts stores are closed !!

Oh the joys !