Leaking Rear Main Seal?

[rustycrocker]

2007 Yukon XL, 170k miles. Have a leak from the bottom of the engine. Cleaned it up and watched for leaks and it appears to be leaking between the engine block and the bellhousing. Guessing it is main seal?

 

[Geotrash]

Check the area around the oil filter. There's a block-off plate where the oil cooler lines would normally enter the oil pan, if equipped, and that plate warps and leaks over time. It's the most common leak point we see on these. And the oil runs down to the bottom and masquerades like a rear main seal leak.

 

[rustycrocker]

I will check that, but the oil seems to be coming from that hole between the pan and the bellhousing.

 

[Geotrash]

I will check that, but the oil seems to be coming from that hole between the pan and the bellhousing.

Understood. A few other possibilities worth checking before pulling the transmission are:

1/The valley cover plate on top of the engine. Most people find that the gasket takes a set over time and the bolts are barely finger tight, so leaks develop that run down the back of the engine. You can look at this with an inspection mirror.

2/ Oil pressure sender on the top rear of the valley cover plate. Inspection mirror will work here, too.

3/ Rear of the valve cover gaskets. Same deal - leaks down the backside of the engine.

4/ Crank position sensor behind the starter. Look for oil beneath the starter.

If you pull the transmission, replace the rear main seal, rear cover seal, the oil gallery barbell, and the torque converter itself, if it's a 6.2L (6L80) and it's original. This will save you from having to do it again in a year or two. The TC on the 6L80 will eat itself (very few will make 200K), and it will take the transmission with it when it fails.

 

[OR VietVet]

The oil may be coming from that hole but.....you should still check what @Geotrash suggested. You also have that round cover you can remove and inspect inside there. If you see wet in there, you guess is likely right. I would also look at back of the intake. If you do the rear main seal assembly, is the perfect time to do torque converter seal and new transmission mount and any other components that you take apart.

Sorry for duplication of @Geotrash. I was typing and posted and then saw his post.

 

[rustycrocker]

I can't see anything near the intake or upper rear of the block. The oil filter is clean and no oil near the block-off plate. There is a small amount of oil near the starter and the bolts holding the starter to the block. When I remove the inspection cover, there is oil on the rear of the block and some pooled up on the little ledge at the back of the block where it meets the bellhousing. Pretty sure it is the main seal.

 

[donjetman]

2007 Yukon XL, 170k miles. Have a leak from the bottom of the engine. Cleaned it up and watched for leaks and it appears to be leaking between the engine block and the bellhousing. Guessing it is main seal?

If it is, here what I changed when I did the job 5+ yrs and 63k miles ago:
Installed rear main seal & cover – Dorman 635-518 - $43
https://www.tahoeyukonforum.com/threads/rear-main-seal-job-pan-etc-07-yukon-denali-6-2.108334/
Performed GM TSB # 10-06-01-008M:
https://f01.justanswer.com/ebrock63...il+Consumption,+MIL+ON,+Engine+Runs+Rough.pdf
and used Gunk Motor Medic $5 to do the piston combustion chamber soak, replaced:
Valve cover driverside – GM# 12570427 - $117
Oil pan gasket – GM# 12612350 - $36
Oil pickup o-ring – Felpro 72401 or GM 12584922 - $9
Torque Converter – P4646 (gopnh.com) Precision- $218
Tranny front pump seal – GM# 24237531 - $30
Tranny Input shaft seal – GM# 24219390 - $10
AFM Deflector – gm#12639759 - $8
Trans cooler line 1 – ACDelco 15779543 - $16
Trans cooler lines 2 – ACDelco 25999420 - $56
Trans cooler clips- ACDelco# 24205103 - $10
Trans cooler gasket - $7
Front lower plastic cowl - $31
Starter – 6757N - $60

No regrets and still going strong at 193k miles

 

[rustycrocker]

20 years ago, I would have jumped into this project, but at 70, I am not up to pulling the tranny with the vehicle on jackstands. And being retired and on a fixed income, I can't afford to have a shop do it. Looks like I will just keep feeding it a quart of oil every month and deal with the puddle under the car.

 

[strutaeng]

20 years ago, I would have jumped into this project, but at 70, I am not up to pulling the tranny with the vehicle on jackstands. And being retired and on a fixed income, I can't afford to have a shop do it. Looks like I will just keep feeding it a quart of oil every month and deal with the puddle under the car.

I understand. I certainly can't see my Father who is around that age taking on this job...

Maybe you can look into a mobile mechanic? It probably depends on where you live, but I've seen guys around here advertising mobile jobs such as brake work, suspension, DOD/AFM and cam swaps. You are not paying shop overhead costs, so the prices seem pretty reasonable. Just a thought...

 

[OR VietVet]

20 years ago, I would have jumped into this project, but at 70, I am not up to pulling the tranny with the vehicle on jackstands. And being retired and on a fixed income, I can't afford to have a shop do it. Looks like I will just keep feeding it a quart of oil every month and deal with the puddle under the car.

At 71, and still working on vehicles at home, I understand. I do lots of different repairs and maintenance work but would not tackle this at home, either. If you are a veteran, you can check at the local American Legion or VFW for possible help, with finding a repair source or even help with the financial part. If all else fails, there are additives that can be poured in that can swell that seal and stop or slow down the leak, maybe. Is not a guarantee fix.