2020 GMC AT4 3.0L/Massive Oil Leak

Granuts55

New member
6
2
Hello, I have a 2020 GMC 3.0L with aprox 7k miles. While I drove home, kept smelling oil burning. Arrived home and backed into the shop, noticed oil EVERYWHERE on the ground. No engine check lights came on. Towed to dealership. 2-3 quarts low on oil. Transmission had to be removed. Determined to be rear main seal, installed incorrectly at factory. Replaced seal and back on the road. 3 weeks later, more oil leaking, just not as excessive. Back to dealership and transmission coming back out to access rear main seal again.
Question-Any other 3.0L owners experience this type of oil leak?
Thanks
 

BoostN

Administrator
Staff member
292
47
TN
Year
2021
Welcome.. this is news to me. Please keep us updated on the fixes!
 

gemarsh

Nebraska, where the Dusty Denali Diesel's roam.
Staff member
283
98
Nebraska
Year
2021
Just did the first service at 3025 miles. Completely dry underneath.
 

MNTIM

New member
24
4
It sure appears the rear main leak is popping up on a handful of trucks. I asked my dealer and they hadn’t had one yet in for that. Bummer and hopefully it’s just a bad batch of improper install or faulty seals. I’ve been keeping an eye on mine. Totally dry at 3500 miles
 

Castry

New member
6
1
Add me to the list didn't even make it to the first oil change. Has been in the shop now for 2 going on three weeks. They replaced the seal thought it was fixed had it detailed and it started leaking again. I guess the GM engineer wants them to replace some seals in the engine now along with the rear main seal again. They offered to submit a claim to pick up the payment do to the longevity of the repair. I'll keep you posted with my truck.
 

gemarsh

Nebraska, where the Dusty Denali Diesel's roam.
Staff member
283
98
Nebraska
Year
2021
Add me to the list didn't even make it to the first oil change. Has been in the shop now for 2 going on three weeks. They replaced the seal thought it was fixed had it detailed and it started leaking again. I guess the GM engineer wants them to replace some seals in the engine now along with the rear main seal again. They offered to submit a claim to pick up the payment do to the longevity of the repair. I'll keep you posted with my truck.
How many miles?
 

Texas

New member
8
1
I have the same issue going on with my truck was driving in from work made it about 3 miles from my house the check engine light came on and it went into reduced power made it home had a trail of oil up the driveway with a large puddle after I stopped. It’s been in the shoo for a week they said it was a blown rear main seal the truck has 4300 miles on it.
 

BoostN

Administrator
Staff member
292
47
TN
Year
2021
I wonder if it's bad seals? Bad factory procedures.. or .. ?
 

Texas

New member
8
1
Well I got mine back from the shop today the understanding that I got from them is that it was improperly installed at the factory. But I don’t trust what they tell me
 

Castry

New member
6
1
They are doing the valve covers on my engine along with the seal again. Apparently that's what the rep wanted them to do.
 

Castry

New member
6
1
Just got my truck back today after 4 weeks in the shop. So far it's not leaking I will keep you all posted. They are picking up my car payment for the month and extending my power train warranty.
 

BoostN

Administrator
Staff member
292
47
TN
Year
2021
Just got my truck back today after 4 weeks in the shop. So far it's not leaking I will keep you all posted. They are picking up my car payment for the month and extending my power train warranty.

Glad to hear they are helping out for being in the shop for that long.
 

Castry

New member
6
1
FYI for anyone who had this problem I was able to get a 60 month 100,000 mile comprehensive warranty bumper to bumper and power train at no cost starting at the date they are submitting the paperwork not the purchase date. I had to options either pursue the car payment for the month or pick the warranty option.
 

LM2 High Country

New member
12
3
FYI for anyone who had this problem I was able to get a 60 month 100,000 mile comprehensive warranty bumper to bumper and power train at no cost starting at the date they are submitting the paperwork not the purchase date. I had to options either pursue the car payment for the month or pick the warranty option.
Thanks for keeping us all in the loop. Good deal and backing to offer that much warranty extension. 11,000 kms on mine including a 2,100km trip pulling a four place enclosed snowmobile trailer though the mountains. So far no leaks, but man did it ever gulp DEF down. Used at least 60 litres of Def on that trip. Averaged 13mpg.
 

Randy

New member
3
0
I have the same issue going on with my truck was driving in from work made it about 3 miles from my house the check engine light came on and it went into reduced power made it home had a trail of oil up the driveway with a large puddle after I stopped. It’s been in the shoo for a week they said it was a blown rear main seal the truck has 4300 miles on it.
Just had same problem 10000 miles on truck
 

Norman

New member
5
0
Is the rear main seal the same as the lower timing cover seal? Does anyone have a part # ? I had same problem. truck is still at dealership. It is 2021.
 
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