Hi everyone!
I've been battling a persistent oil leak coming from the back of the engine, right side just behind the timing chain cover.
I've replaced the upper oil pan gasket and o-rings, lower oil pan gasket, timing chain cover gasket and rubber mains as well as valve cover gaskets.
Only thing left I think is the back shell side of the timing chain cover, but that requires removal of the chain, gears, tensioner, water pump - quite a job and I'm anxious to dive that deep in.
I haven't found much online for the timing cover back shell to the engine block seal.
Anyone have experience with a leak like this?
I smeared sealant around the area but to no avail - still leaking - just enough to be a major nuisance.

This is a 1998 GXE with 212,000 miles, but still a lot of life in her!

Added note:
I should also mention that the car was launched onto a rock wall by my teenage son back in November, I replaced the engine and trans pans as they were scraped.
I haven't discounted that the block may be cracked. And sort of makes sense that it leaks only after heating up... may be time for a few tubes of JB weld!!

Thanks in advance,
Wayne

 

I believe that other than those under the timing cover... common leaks on that side come from cam position sensor (up top though), front crank seal, oil pressure sending unit switch. Not sure if a rear leaking valve cover gasket might make its way down there, but that's something to consider.

 

Thanks! I did replace all of the above and confirm they are dry.
The leak is coming from above the upper oil pan a little deeper than the timing chain cover, more like where the inner timing chain housing mounts to the block.
Maybe adding dye to oil would help? I've never used those types of diagnostic tools.

Thanks!

 

the dye would be a very good idea. You could see where it's actually coming from.

I suppose that it's possible that the timing cover was hit sideways. That could cause the gasket to move a bit, creating the leak.

 

Had the same leak. It was the inner orings inside the timing cover. You do have to remove the timing chain but not a big deal, just line up your 3 timing marks on chain before you dissasemble. I have done this 3 times on 3 different cars. I found that getting oem orings is the way to go. I used a dab of grease to hold the orings in place until I could get inner cover back on. Make sure you follow the sealant application as described in the service manual.

 

And to add to what sdunker said, RTV for the timing Chain cover. Gaskets don't last.

Maybe think about a new Timing Chain since you've already gone that far and a new tensioner as well with that many miles. Then you'll have a really long way to go before retiring it at over 400K.

Also check the Power Steering system. That has been the culprit and fooled many as well.

 

I removed and resealed the timing chain cover, new crank seal and half moons, cleaned up all the surfaces and grey rtv - I didn't see any o -rings under the timing cover though.
Are they under the tensioner?
I did replace the 2 O rings around the oil pump passages on the upper oil pan, as well as the lower half moon and sealed it up tight.
No leaks from any of those surfaces, but that one persists directly above the oil pressure sending unit.
Drips off the lip on the block, down the harness that is routed behind the axle and onto the sending unit.
Was a 3-4" diameter puddle, now is a 1-2" diameter puddle, so I made some difference, maybe with the pile of sealant I added to the block.
Only leaks after it gets hot, and drips for about 3-4 minutes and stops.

Ready to JB weld this bugger and call it a day.

 

Also, power steering pump and lines replaced. No leaks.

 

There is another cover under the large timing chain cover. Can't see it until you get it apart. There are two orings under this inner cover. When they go bad they leak out by the oil pressure switch.