Lately I've noticed a sort of petrol/oil ish smell from my coolant. And what looks like traces of something floating on top. Is this the first sign of a headgasket starting to fail?

I gather headgasket failure isn't very common on this model but still totally possible I guess.

I've only really noticed it since taking the car off the road last year, and giving it the odd blast. No overheating and doesn't seem to be using coolant. Running perfect otherwise. The coolant is brand new genuine Subaru stuff. And the radiator is brand new. Pics attached of the coolant in the expansion tank!

Thanks

 

Certainly that's how mine started (for the second time!) with contamination of the coolant with black oily sludge in the expansion tank, for me it was H/Gs but it's been mentioned that it could also be a cracked cylinder liner.

In either case it's likely to be combustion gases or oil getting in to the coolant. Might be worth doing a few decent 'pulls' on boost and checking the tank immediately after with an exhaust gas sniffer test, this is one way to check it. They are cheap on ebay and really easy to use. When my car finally started overheating the tester fluid turned yellow after 4 squeezes of the pump...


ebay: http://www.ebay.co.uk/itm/Block-test...GcU0xCN4qZ-Xow

 

Thansk for the reply Bazil!

I've had a look at that link, that looks like a handy bit of kit. I may try it.

I think really I should probably have a pro look at it anyway. I guess somethings not right anyway, I'm sure either way its going to put my lights out

 

Sniff test and go from there

 

Looks like oil to me may have come from a failed oil cooler. HG failure usually causes overheating especially when driven hard on boost, and coolant loss when the when it spews out of the header tank. One of the first symptoms for me was my heater only blowing cold due to the system making it's own air and air locking.

 

I wasn't even aware they have an oil cooler. Where is it located? My car has none of those HG symtoms you've mentioned. Is fine on full boost and when idling the fans cut in and out as normal. Doesnt seem to be building abnornal pressure in cooling system either.

My pictures make the specs in the coolant look white but they're not. Thats just the flash.

 

Oil cooler on yours will be the modine,where the oil filters sits.

 

Thanks ossett2k2. I hit google after Richard J's comment and read about modine oil coolers, I didn't even know they existed so i've learned today!

I've been out to look at my car and it seems to be quite oily at the oil cooler/filter and the surrounding area. And can see the wee drop on bottom of filter. Would this have any significance if was a failed oil cooler? Or would my problem be caused by the oil cooler failing internally somewhere.

 

Oil and coolant both flow through the oil cooler so it's possible there is an internal leak there.

From my experience at least the symptoms of head gasket failure were/are:

Contaminating the coolant with an oily film to start with and bubbling in the coolant tank after a decent run, then an oily sludge build up on the side of the tank and on the rad caps. All the while no other apparent issues were noticed.

After months and miles it would only overheat when slowing down after a decent run like country roads going to town driving, and very quickly after that it would overheat even at idle.

Each represents a stage of severity of hg failure I think.

 

This was the cause of my v3 head gasket failure which resulted in following symptoms,

heaters suddenly blowing cold due to combustion air lock in heater matrix,
occasional slight over heating
overpressurizing coolant system when driven hard and spewing out of header tank.

Ran it like that for a while 1-2 months driven very carefully and ended up with melted exhaust valve on chamber 2 due to hot spot on that cylinder.

The black sealing material from the head gasket has totally delaminated from the steel MLS face probably due to previous owner over boosting via bleed valve and running to lean from not being remapped for that amount of boost

Your symptom of oil/water contamination is not the usual type of head gasket failure but it is possible still. Usually they go between the coolant and combustion area which is the thinnest sealing area on the head gasket