Oil in Coolant. Replaced Oil Cooler - Still mixing

[rgracin]

As per title really. D5 185bhp witH 150k manual.

Had oil in the coolant expansion tank. Garage replaced the oil cooler, flushed the system once using the dishwasher tablet method.

When started after, oil has appeared in the expansion tank again. They idled it up to temperature for over an hour. No overheating, but they are suggesting it may be head gasket. I know that’s quite rare on these engines.

Could it be it needs more flushing. Whats people’s thoughts. Have you done the same and need to flush more than once before the oil stops mixing?

Keeping my fingers crossed.

Thanks

[Simmy]

did they confirm by testing that the oil cooler was faulty? dose your car have a transmission cooler built in to the bottom of the radiator? after one of these type of events it can take a few flushes to clean the system. the transmission cooler was a known failiure point on 850 / v70 if system was filled with tap water or weak coolant mix

[rgracin]

Not see if it’s got a transmission cooler. I wouldn’t have thought a manual does, but stand corrected if needs be.

In any case, it’s engine oil not transmission fluid in the expansion/header tank. Don’t think they tested the oil cooler.

[mcfe]

The manual shouldn't. Well, with the oil cooler replaced, the only other way is head gasket. So that is your next culprit.

Also, when you have the head off, by yourself or a shop MACHINE it, if it's not flat just replacing the headgasket will make it fail again. Also have it tested for cracks, if it's cracked it's going to fail forever each time you repair the car.

[ASt85]

Originally Posted by rgracin

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Could it be it needs more flushing. Whats people’s thoughts. Have you done the same and need to flush more than once before the oil stops mixing?

Keeping my fingers crossed.

Thanks

It is a good idea with any oil contaminated cooling system to do a reverse flush as you are more likely to clear oil contamination by passing flushing water up through radiator matrices where the water normally flows from the top to the bottom of the radiator or heater matrix. The relatively low speed of the water moved by the engine's water impeller (aka pump) is insufficient to force all the oil down the radiator.