BitBasher

Hey Guys, Our beloved a6 avant, the one that we thought would live forever, just suffered a major aneurysm. With 340k km she was still going strong, but no longer. Yesterday morning was fairly cold, -10c, I started her up and left her running to warm up. Ten minutes later my wife heard a knocking noise and noticed a large pool of oil on the ground and shut her off. I jacked her up, pulled the belly pan and had a good look. I couldn't see anything obvious so I suspected that maybe the oil cooler gasket had blown out. I loosened the oil cooler and had a look. The nut wasn't very tight so I thought maybe that's it. Being in the 'sticks' I had no parts but did have some red silicon gasket maker. So I applied some silicon on the rubber gasket and put it back together. I managed to find five litres of oil and put it in and started her up. A heavy stream of oil, maybe the thickness of my little finger, was pouring out. And the engine had some noticeable knocks. So I'm pretty sure she's done for... but where could the leak be coming from? Perhaps the oil pressure sender has ruptured... or could there be an oil galley plug that's popped out of the block?
This doesn't seem to be a common problem; has anyone any ideas? Thanks /PL

Kris Hansen

Pouring out of where? The cooler gasket?

BitBasher

I thought it was coming from the cooler gasket. I loosened it off and had a look, it seems to be fine. I have some 'recycled' oil from my 996 that I'll pour in and get my wife to start her up while I'm looking. Sure not obvious though. And she bled like a stuck pig on the deck of the wrecker!

Airbag

if you heard knocking after you filled it back up im afraid that engine could be done...

BitBasher

I pulled the oiler cooler and found the problem. The rubber o-ring gasket was split. And I had one that I'd bought five years ago but never got around to putting in... 'cause it's a bit of a pita to re and re the coolant hoses.

She was a bit clicky but wasn't knocking after start up so I was optimistic. After about five minutes she quietened right down to her normal purr. I expect the clicking was due to the hydraulic tappets being empty. Went out for a drive to see if all was well with hot oil... yes! still good. Looks like we lucked out on this one. Probably a combination of a recent oil change with good synthetic (Mobil 1 Delvac 0W-40, the best), and cold ambient temperatures.

The gasket looked like it had been stretched, which was undoubtedly due to the oil cooler twisting while removing a stubborn oil filter. It probably was brittle due to the cold and being under tension stress it snapped as the temperature rose... or something like that ;-).

The moral of this story... CHANGE THE OIL COOLER GASKET WHEN YOU DO A TIMING BELT JOB. You have already drained the coolant and have good access to the hoses, piece of cake!

SloopJohnB@mac.com

I'd have to disagree. The oil cooler gasket would not have failed if the oil cooler was tightened properly. That gasket is life-of-vehicle or until it fails. It's not a wear item.

BitBasher

or until it fails? Think about it. Every time you change your oil filter you're fitting a new oil filter gasket. Does it make sense to assume that the oil cooler gasket is going to last the life of the vehicle... maybe if you're in the 'lifetime fill atf' camp. LOL.

Airbag

I replace mine once every 5 years or so.. They go in rubber and come out hard plastic.

Btw I got an extra nut and remove the nut holding it on. Then I use the double nut to take the pipe out it sits on. Screws right out. Replace gasket then out it back. No coolant pipes to deal with. Takes an extra 10 minutes when doing an oil change

Sounds like you got away with one.

SloopJohnB@mac.com

?? The oil filter gasket on the oil filter is a whole different animal compared to a gasket that is part of a housing. The oil filter is scheduled maintenance…it gets removed and replaced by time and mileage. The other gaskets on the engine are not.
That's like saying you need to replace the valve/cam cover gaskets every oil change because they might leak. I've got 180+K miles on my 2K4.2A6 and the valve covers have not been off the engine…no leaks either.

Things like that gasket on the oil filter housing get replaced when they leak, not on a scheduled basis.