What's leaking at the back of my engine? Everything?
 

Doing a clutch job due to my pilot bearing exploding (cause seems to be torn transmission mount) And there's a lot more oil on the back of my engine than I expected. I sprayed some PB blaster getting the flywheel off so it's a little hard to tell by the pics but if any leak experts can give me an idea of what they think is leaking I'd appreciate it.
https://cimg2.ibsrv.net/gimg/ls1tech...a23a24a9c2.jpg

Also, any secret seals that can leak back here other than the rear main seal?

https://cimg8.ibsrv.net/gimg/ls1tech...9fab88c2f5.jpg
Oil sending unit?

I had a leak on my 06 suburban LQ4/4L80e. I had replaced the oil pan gasket like 1.5 years prior.

Started from the top and worked my way down. Valley cover gasket and camshaft (replaced the cam sensor even though it wasn't "bad".) I think both were leaking just a tiny bit.

Rear main seal was the culprit. Replaced that and it's been pretty clean down there for the last 5 months.

Truck has 255k and every gasket or seal I'm pretty sure were original.

2 weeks ago replaced the oil pressure sender, but it had failed giving a bad reading.

Definitely gonna replace the rear main seal. My only worry is aligning the cover but I guess I can get a tool for that. I wonder if the RMS can throw oil around due to the rotating crank and flywheel etc

There is a rear cover behind the flywheel that the rear main seal is in, which has a gasket of its own.
Under that is the barbell which diverts flow to the filter. It could possibly lesk.

When I put a new rear seal in mine it came with a plastic alignment thing in the seal so there was no need for a tool.

Hey, Gary, IIRC, the barbell is under the rear cover. I don't think it can leak externally unless it's thru a bad cover gasket, or cover seal. Again, IIRC, lol!!

Whatever it is, it's inside the bell housing. Seal, cover gasket, or pan gasket.

Do the simple eeeeeezzzzzzy and obvious thing. Replace the whole rear cover. https://www.rockauto.com/en/moreinfo...pt=695&jsn=658 for example. I don't think you can buy the seal & gasket for any less. As well as, that totally dodge the issue of successfully installing the seal.

I'd STRONGLY suggest that you Heli-Coil the 2 holes in the bottom of the cover for those long oil pan bolts before putting it on though.

Might not be a bad idea to also buy an oil pan gasket, carefully cut out the section across the back under the cover there, and replace it as well; with a bead of Right Stuff or similar in the corners.

It is a worst case scenario.
IF the barbell leaked, AND the cover gasket leaked, it would show just like a main seal leak.
Just exploring the (remote) possibilities...

One bad thing about replacing the entire cover. The GM covers are quality tested for porosity. The cheap Chinese replacement more than likely is not. While it may be just as cheap to get the cover and seal as an assembly, 99.9% of the time a new cover is not needed, only the seal. By buying the complete assembly, youre chancing substituting one problem for another. If the OEM cover is good, I'd recommend just replacing the gasket and seal. My .02

Yep, I also replaced the little barbell diverter. I don't think that will cause an oil leak, but can see it causing a larger leak if rear main seal is already leaking and diverter valve is also leaking? I don't really know. I'd figured might as well replace it.

Also replaced the torque converter lock up o ring and transmission front seal, "while I was in there." Obviously does not apply to OP.

I used the centering tool from SacCity. It was around $40.

GM has a new style rear cover....dont know if yours has it already....supposedly the old style leaked around bolt holes

things that can leak back there

rear cover gasket
valley pan gasket...leaks down
cam sensor...leaks down
rear main seal
oil pan gasket....oil sprays up and everywhere
oil pressure sensor...leaks down

Thanks for the tip. Went ahead and ordered a GM rear cover and 'barbell' like others have said. Did some searching and haven't heard of the helicoil thing but I'll look into that.

Since I've had the car I thought my oil pan was leaking but this is a lot worse. I thought you had to drop the K member to do that? If not then now would be a good time. Once I'm done underneath I'm definitely gonna pull the intake and change the oil pressure sending unit and cam sensor or whatever it is too.

Heli-coil strengthens the threads for those 2 long bolts, which since they are fine thread and just go into aluminum, are SOOOOOPER EEEEEEEEEEZY to strip. For all you know, the only REAL problem you might have, is that some g00b PO already overtightened those, and stripped out the cover. Possible you could fix it by just Heli-coiling your existing one but for a small stack of $.01s why bother if you can just buy a whole new cover, make it indestructible with a Heli-coil, and put the whole deal in your rearview mirror, FOREVER.

Not advocating dropping the oil pan. Leave it in place, cut out the section of the gasket in question, put in the new cover. Avoid complications. I don't know what kind of car this is but I know from a half century of experience that an oil pan gasket is a WITCH with a capital B in many chassis. If the rest of the pan doesn't leak, no sense in disturbing it.

Your leak doesn't look like the CPS, OPSU, or valley cover. Looks like it's coming from inside the BH. I see no oil whatsoever anywhere else. Now, I'm not saying "don't replace the [other parts]", [those things outside the BH] are all perfectly good", "your leeeeek is the cover", NOT NOT NOT NOT NOT NOT NOT. Don't put those words into my mouth (as some have been known to do). Only, your leeeeek looks like it's INSIDE the BH, not OUTSIDE, so FOCUS on things that are INSIDE the BH, in the most cost/time/labor/$$$/risk/reward effective way possible. ;)

I would briefly note also, nothing about engine mounts can damage a clutch. If your clutch grenaded, the root cause is NOT a transmission mount.

As above, I am NOT saying "your trans mount is fine", "don't change your trans mount", or ANYTHING of the like. NOT NOT NOT NOT NOT NOT NOT. Go ahead and change it if it's fornicated. Butt, that is NOT the cause of any clutch malfunction. You'll need to dig a bit deeper, or, just accept that the clutch exploded because... it felt like it. Or was abused. Or there's SOMETHING ELSE that destroyed it. Butt, IN NO POSSIBLE UNIVERSE that you might be living in with the same rules as ours, did the trans mount damage your clutch.

The clutch came out just fine, it was the pilot bearing that exploded. A few other threads discuss how even a slightly misaligned input shaft (which would be thrown at a weird angle if the trans was bouncing around) can destroy a bearing. Maybe you didn't see the second pic I posted but there's a good amount of oil around the driver side head. But good advice on the bolts I've been seeing a handful of threads where people snap those bolts

I would change out the camshaft sensor seal as well

The trans alignment re. the pilot bushing can't "bounce around" because of mounts. That can ONLY happen if the trans isn't bolted securely to the motor.

Never seen anybody snap those oil pan bolts, but that certainly doesn't mean it doesn't happen. I can see how it easily could. The whole system of them is weeeeek. Strengthen what you easily can (the threads) and be careful about everything else.

Looks to me like 95% of your oil leeeeeek is inside the BH. Note that I DID NOT say that the things up top "are good", "don't change them out", etc. etc. etc.; only, that something INSIDE the BH is leeeeeeking in a very big way. By all means renew whatever you have access to and that seems like it could use it.

Driver's side head looks to me like the valve cover gasket. Might be good to hit those while you're at it. Not serious or horrible, butt, no sense in leaving it defective, if it in fact is.

Fair enough...now that I think about it I had a hard time installing the trans back in the first time I did a clutch. I think maybe the alignment tool was drooping a little and threw it off center. Can't remember if I pulled the trans in with the bolts or not (which I now know is a big no-no). Just got the cover in the mail gonna throw it on tonight

There is absolutely nothing wrong with drawing a transmission down with the mounting bolts. BUT-You've gotta be careful, and use common sense. If you're drawing it to the block, or whatever it is being drawn to, take your time, and tighten bolts evenly. If you suddenly find the bolts getting harder to turn, and the trans isn't getting closer to the mating surface, STOP, and rethink what may be happening. Now isnt the time to put a 3 foot pipe on your 1/2" drive ratchet, and twist it in your best John Cena impersonation. Use NO POWER TOOLS!!!