[Elevation-343]

Just had my 2020 Elevation towed to the dealer today. 8700 Miles, blown rear seal. Oil all over the driveway.

 

[98whitelightnin]

Ive had mine almost a week and about 450 miles, knock on wood, no leaks yet

 

[Ron Nielson]

Copy of article attached. Perhaps not all the techs have seen this.

 

[bdgags]

Hi all, I have a new (I have had it 7 days) AT4 3.0 w/ a rear main seal failure at 300 miles. Had the truck 7 days. At dealer now for extensive dismantling and repairs.
Anyone else have leaks very early on with this engine? I am worried about a defect in the block machining where that seal fits.

Same thing has happened to me twice! Its in the shop now; I have just over 7000 miles on it 2020 Sierra Denali Duramax

 

[Philisophe]

There are a number of complaints/reasons for the Rear Seal failures some are as follows....



1.Plugged pcv orifice causing rear seal oil leak
2Catch Can Install
3.Lifted Truck/Oversized Tires/
4.Improper Seal Install From The Manufacturer
5 Poor Transfer case Machining




There are some very well versed individuals on this forum so ..Im curious does anyone have any suggestions as to why. And why so many issues in such a short span of time..

GM says the PVC causes most failures. It appears the transfer case fluids expand and cause the seal to “leak then blow out”

But after the seal is replaced by a dealer the seal failure never returns..

I have my theory as to why in most cases( not all) the seals fail..

These seals must be kept flexible and the oil is the most important component.

Please see the following

Is it the rear main seal that is leaking?

It might not be. On most engines, oil leaks can occur above and below the rear main seal. It could be a leaking oil pressure sensor, oil pan gasket or galley plug near the seal that causes oil to come from the bell housing. Adding dye to the oil can help reveal where the oil is coming from.
Is the PCV system clogged or blocked?


Most rear main seals have a lip that rides on the shaft. The pressure inside the crankcase will push the lip onto the shaft. Too much pressure will eventually cause the lip to balloon and allow oil to pass. If the Positive Crankcase Ventilation (PCV) system is blocked, it will increase the pressures inside the crankshaft and push out the seal. Also, if the engine is supercharged or turbocharged, excessive blowby due to worn or damaged piston rings can cause increased crankcase pressure that can also damage the rear main seal.

What is the condition of the oil?

Most oils have chemicals in their additive packages that will condition the seals in the engine. If the oil is not changed regularly, it will cause the seal to degrade. The seal conditions are depleted over time along with buffers in the oil. The lip that rides on the crankshaft will become stiff and will not be able to seal itself against the crankshaft.

What is the condition of the crankshaft?

The condition of the surfaces that the rear main seal rides on is critical. Any imperfections or wear on the crankshaft can cause a leak. There are sleeve kits that can be installed on the crankshaft to restore the surface.

Did you follow the directions that came with the seal?

Some rear main seals need to be installed dry. These seals have a polytetrafluoroethylene (PTFE) coating on the lip seal that needs to be dry and seat to a dry surface on the crankshaft. The seal will transfer a layer of PTFE to the crankshaft surfaces that the lip will ride on. The transfer layer prevents wear while sealing better than a silicone or Viton material. If the seal is installed with a coating of oil, it will start to leak in a few miles.



I believe that there is a distinct relationship to the quality of the oil..Outside temps



And how long have these NEW trucks been setting..Have the seals become dry and are destined to fail..



Any thoughts

 

[jay p]

Not sue what the transfer case has to do with it since there transmission between the engine and transfer case.

 

[Philisophe]

Not sue what the transfer case has to do with it since there transmission between the engine and transfer case.

Hope this helps


As a senior tech quotes


"The transfer case output shaft seal is located on the transfer case of four-wheel drive cars, trucks, and SUVs. The transfer case completes the activation between two-wheel drive neutral, to low four-wheel, and then to drive four-wheel. Inside the case are a series of gear reductions and chain drives that work together to accomplish their task of supplying power to the drive axles, making the vehicle four wheel drive.


The transfer case output shaft is the part that connects the case to the axle. The purpose of the transfer case output seal is to prevent fluid from leaking out of transmission, where the transfer case is connected by way of the transmission's input shaft. The seal also helps to keep fluid from leaking out of the front and rear output shaft to the differentials, which keeps all metal components properly lubricated for extended use.


If the seals leak, fluid escapes and is no longer able to properly lubricate the interior components of the transfer case. Eventually the parts inside will wear out and overheat. If this happens, the transfer case will be rendered useless and the four-wheel drive operation will not work. Over time the transfer case output shaft seal can fail, and when it does, will display a few symptoms that will alert the driver that a problem with this system exists. .

 

[jay p]

I know what the transfer case does but what does the transfer case have to do with a rear main seal leak on the engine. That was my point!!!! -> NOTHING TO DO WITH IT
That "engineer or tech" needs to go back to school.

 

[redwngr]

As posted by above by Ron, the 3.0 has the timing cover on the back of the engine, and the seal is in that cover.

Depending on what is found, the repair may require replacement of the cover as well....

Diesel Engine Rear Main Oil Seal – TechLink

gm-techlink.com

Diesel Engine Rear Main Oil Seal
April 13, 2021
Some 2020-2021 Silverado, Sierra; 2021 Tahoe, Suburban, Yukon and Escalade models equipped with the 3.0L diesel engine (RPO LM2) may have an oil leak concern and DTC P06DD (Engine Oil Pressure Control Valve Performance) may be set. These conditions may occur if the rear main oil seal has moved or is severely shifted out of position in the timing chain lower cover.
If these conditions are found, replace the timing chain lower cover, which comes with a seal already installed. (Fig. 9)

Fig. 9

If the seal is tilted out of position, use a caliper and record the depth where the seal is pushed in prior to removing the rear cover. Also place an indexing mark on the seal and cover, which will be helpful to the Warranty Parts Center in case the seal falls out or moves during shipping. (Fig. 10)

Fig. 10

Record the Part Unique Number (PUN) found on the white label attached to the back of the cover.
The timing chain lower cover comes with a two-piece protector/installer. The inner piece becomes the installation tool. (Fig 11, A) The outer piece simply holds them together for shipment. Remove and discard the outer piece. (Fig. 11, B)

Fig. 11

The inner piece acts as an installation tool substitute for the EN-52466-2 seal protector and fits over the bevel on the end of the crankshaft. Be sure that the inner lip of the seal slides over the rear of the crankshaft without rolling during installation or a repeat oil leak may occur. The protector/installer (Fig. 12, shown without cover) will have a snug fit to the pilot of the crankshaft.

Fig. 12

 

[Philisophe]

Consequently, Almost 90% of all rear main seal oil leak complaints, were actually leaks in the pan gasket, rocker covers, side covers, etc., and are not leaking rear main oil seals.

Rear Main Seal Leak



Good To know..Just trying to determine actual causes

 

[Luc Janelle]

Hi all, I have a new (I have had it 7 days) AT4 3.0 w/ a rear main seal failure at 300 miles. Had the truck 7 days. At dealer now for extensive dismantling and repairs.
Anyone else have leaks very early on with this engine? I am worried about a defect in the block machining where that seal fits.

my new AT4 2021 seal crank oil leak at 12,000 kilometers very disappointed I go back to 6.2l

 

[Cajun Boys]

I have a new 2021 GMC with the 3.0L,purchased May 12,2021. Noticed a small drip on skid pan, then onto ground; we put it on rack & it seems its a small sepage from front seal of Mtr, behind Harmonic Balancer. A few master mechanics(not GM) told me use it & put about 1000 miles on it...? Fingers crossed , Will see

 

[dirtymainer]

I have a new 2021 GMC with the 3.0L,purchased May 12,2021. Noticed a small drip on skid pan, then onto ground; we put it on rack & it seems its a small sepage from front seal of Mtr, behind Harmonic Balancer. A few master mechanics(not GM) told me use it & put about 1000 miles on it...? Fingers crossed , Will see

It is under warranty, their advice makes no sense. If your truck is brand new and leaking oil then take it to the dealer, period..

 

[redwngr]

If your truck is brand new and leaking oil then take it to the dealer, period..

^^^this^^^

Even if the first visit the dealer just looks at it and wipes it off.

 

[Growland70]

2020 Silverado RST 3.0L Duramax LM2 with 12500 miles. Never towed a trailer or put under stress. Rear main seal blown and oil everywhere on my driveway. Dealer says 12+ hour repair.

 

[dirtymainer]

2020 Silverado RST 3.0L Duramax LM2 with 12500 miles. Never towed a trailer or put under stress. Rear main seal blown and oil everywhere on my driveway. Dealer says 12+ hour repair.

what happens exactly? does it throw a code and shut down or keep running with no oil?

 

[Growland70]

Yes, it went into Reduced Power Mode and the check engine light came on. It kept running fine (reduced power aside) back to my house, and then to the dealer in the morning. The dealer checked the code and thought it just needed an oil change. When they got it up on the rack, they could see oil everywhere.

 

[dirtymainer]

Yes, it went into Reduced Power Mode and the check engine light came on. It kept running fine (reduced power aside) back to my house, and then to the dealer in the morning. The dealer checked the code and thought it just needed an oil change. When they got it up on the rack, they could see oil everywhere.

Do you think you did any damage running it with very little oil?

I'd be pretty pissed if they just slap a new rear main seal on it and call it good, who knows what went on internally.

 

[Growland70]

I totally agree. I have seen several people who have echoed that same sentiment. I am doing research and trying to figure out how I proceed. The thought of driving my $50k+ truck without oil makes me sick and pissed at the same time. I will definitely keep updating as this community of folks will only continue to grow as the Cadillac SUVs, Tahoes, and Suburbans all start to hit the magic 10k mileage mark.

 

[tdhanses]

Has this happened to many 2021’s?