Rear main seal

Welcome to the forum Randy.. I've seen a few occurrences of this. Is yours a 2020 or 21?
 
My rear main seal, went out at aprox 7000 miles. GMC dealer said the main seal was installed incorrectly at factory. Truck was down 6-7 days. I got the GMC back and still had small leak. Back to GMC dealer and another 6-7 days. GMC dealer said, their tech did not install, the new rear main seal correctly. GMC dealer owned the fix and admitted improper installation. At aprox 12k miles now and no leak. No other problems at this time.
 
New to this motor, so not sure if rear main seal is the same as lower timing cover. Just lost mine. 3900 miles. Truck is still in shop. Oil all over driveway. Do you have a part # ?
 
You are replacing the seal yourself?

I thought I was bad for not going to the dealership. No way in hell I would do it on a 4k mile engine with warranty.

I'm sure the dealer would find the part number for you.
 
Hello everyone my rear main seal blew out with 6011 miles on the odometer
 
There’s another forum where the number of trucks with this issue is going up. Which sucks since I have a 2020...it should be a recall for GM if it continues.
 
Let’s hope GM steps up to the plate and acknowledges the issue.
 
Let's hope GM has a fix and we don't all succumb to endless stack ups replacing this over and over.
 
I was talking with my son, who is a heavy equipment tech, about this and he thinks it could be a problem with the PCV system if it builds up too much pressure it will blow out the seal. Although it's entirely possible that it's either a poor design or a batch of bad seals, it could be pressure blowing out these seals.

There isn't any info out there yet beyond what GM is letting trickling out.
 
I have a 2021 GMC Denali with the 3.0L and having it towed to dealer today. I think the seal is blown with 11k miles. Barely made it home and oil everywhere under truck. No oil on dipstick. I will post what they say.
 
I have a 2021 GMC Denali with the 3.0L and having it towed to dealer today. I think the seal is blown with 11k miles. Barely made it home and oil everywhere under truck. No oil on dipstick. I will post what they say.
Sucks, keep us updated!
 
Sucks, keep us updated!
It turns out that my oil filter was leaking. I usually do my own oil changes but the first one was included so I let the dealer do it. They told me that there was a small hole in the oil filter. I asked how that happened and they said it was over torgued. How does that happen with an oil filter? They changed the oil and filter but I know I was several quarts low and I had to drive about 50 miles home like that since you can not buy the DEXOS-D oil anywhere but the dealer. I have never had an oil filter leak in my 56 years. Motor sounds fine but I will be doing all my own service for now on. (Whenever possible)
 
It turns out that my oil filter was leaking. I usually do my own oil changes but the first one was included so I let the dealer do it. They told me that there was a small hole in the oil filter. I asked how that happened and they said it was over torgued. How does that happen with an oil filter? They changed the oil and filter but I know I was several quarts low and I had to drive about 50 miles home like that since you can not buy the DEXOS-D oil anywhere but the dealer. I have never had an oil filter leak in my 56 years. Motor sounds fine but I will be doing all my own service for now on. (Whenever possible)
Good to read.

Never had a hydraulic, fuel, coolant, or oil filter leak, 'cept for a double gasket oops, in 40 years of turning wrenches.
 
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