Hi all, I suspect that I may have a leaking oil cooler on my 4.4 L405 however there are no obvious signs that a DIY guy like myself would consider major. I did ask my local Indy to take a look and, even though they say they can see a little oil at the back of the engine when looking from underneath, it is not enough to be certain where it is coming from without starting to take things off to give better access so they have suggested I wait until any leak starts to become more noticeable. There is no oil dripping and there is nothing on the driveway that I can tell. My only suspicion of the oil leak was fumes in the cabin which made me suspect the oil cooler. The oil level has remained consistent and so has coolant so it is likely very early days of this common problem?

I am happy to leave it for a while as I hardly do any miles but am interested in what other would consider the warning signs to be that would drive you to decide to get a repair done? Oil dripping on the drive? Wet oil on the underside of the engine?

If you know someone with an endoscope you could try and find the source that way. could be oil cooler or just the o ring on the feed pipe at the back of the oil cooler. If its the oil cooler the leaking oil usually tracks down both sides of the bell housing after pooling up in the V of the engine. This can be seen from underneath with undertray removed. Mine failed at 42k and 7 years old. Not sure if i would be happy to just let it develop into a more noticeable leak but certainly monitor it every day.

I’m in the same boat but mine is more obvious. I saw drips on the drive. I bought a £30 endoscope and found coolant in the V by the cooler.

Personally I would not risk driving it. There is a possibility of coolant contaminating the oil and then you may have a whole heap of problems. I would get it looked at asap.

Jmho