Oil cooler woes

[johnny_quattro]

I have what I suspect is a leak from the oil cooler on my 4.2 A8L facelift model, 2000. Checked the oil (as I do every fortnight or so) and was alarmed to see so little oil on the dipstick. Looked underneath and I could see oily parts on the plastic undertray.

Could someone take a look at the attached photos and offer any advice, in particular with regard to not only why these things break but also that oil cooler coolant pipe made out of plastic? I don't think mine is broken as the overflow container is just full of the red coloured antifreeze mixture and is certainly not that chocolate brown emulsion thing.

What is more likely - is it the seal/gasket that's gone or is the whole unit going to be needing replacement? I have already ordered one of the those replacement aluminium parts that is referred to in many posts on this forum. My thought process being, if the oil cooler is indeed shot, then it would need to be replaced but I wouldn't want a new part installed with the same old plastic coolant pipe being put back in.

I'm somewhat clueless on this so I've already warned the garage of the silver QE2's imminent arrival. Any ideas on roughly how much labour would be nice to know.

Cheers all, happy New Year to you all.

[David's8]

'fraid cant offer any helpful advice / info here as my knowledge about this is limited to reading the threads about this issue on the forum but I hope that it gets resolved OK.

[Goran]

There are much more knowledgeable people on here than me, but I would at first say to not immediately suspect any part without proper investigation. Pull all those plastic covers off and undertray, and have a good look all around the block with a torch. These engines can leak from the valve covers, cam shaft seals, sump tray, some large round seal at the back hidden by the transmission (very common as it rarely gets replaces -trans out job).
If you have patience clean up all the oil you can see, dry everything, then after driving the car next time have a look to see where the oil is coming from before it spreads everywhere.

Only if the oil is freshly leaking out from the oil cooler unit itself would I suspect replacing it. Plastic pipe that often fails is a coolant carrying pipe between oil cooler and block and should have nothing to do with oil.

[johnny_quattro]

Just to embellish my previous post, I was suffering from a permanent coolant loss, not massive amounts but I've probably filled it with 2 containers of antifreeze since I've had the car - which was purchased 3 years ago now.

My car is booked in at the local garage when I can get time off work. I do suspect that it is the oil cooler but this will have to be confirmed when the grease monkeys get the car up on the ramps and have a good look.

Will keep everyone posted. The aluminium part I ordered from the chap in Austin, Texas turned up this morning and looks very good quality indeed (see attached photo.) I though that I'd try and kill two birds with one stone with this approach.

[johnny_quattro]

It turns out my oil pressure switch had bitten the dust and was pi55ing oil out in reasonable quantities when travelling. Only a few spots were noticeable under the car though. Nice easy job for the garage.

I'm not going to get the oil cooler replacement part fitted as that looks like a ball-ache of a job from what I've seen of my engine bay today - one for when the weather turns nice again, which might be a while.

[johnny_quattro]

My oil pressure warning light illuminated on the dash last week, and the oil pressure sensor was only replaced just under one year ago. Popped it down to the garage, and the part was replaced this time with a black version from TPS, so the one previously fitted didn't appear to be up to the job.

Just thought it worth mentioning here in case someone hits the same problem - black is good, grey is bad.