Suggestion and Opinion on Changing Rear Bearing Seal?

[Jozseph]

Appears I have a leaking rear bearing seal.

As I never changed one;

Is it possible to just remove the oil pan with out raising the engine, remove the lower rear cap to change the seal?

Looking on line I see there is a tool by Lisle the "Sneaky Pete Tool" to assist in removing and installing the upper rear main seals without dropping crankshaft.

Felt Pro manufactures a two piece molded neoprene seal.

Any suggestions and opinion?

Joseph

 

[cucvrus]

I have done many rear main seals in the 6.2. It is a dirty job and can be a real chore if the bolts are rusty and the oil pan is leaking. You no not need to remove the motor mounts. You will need to remove the starter or work around it. I always remove the starter. I never used any special tool. I just slipped the new seal up in place an d put the joints at about 1 o'clock and 7. Somewhere other then 3 and 9. You do not want the seal aligned with the bearing cap. I think it is outlined in the CUCV notes. I use Permatex the right stuff and a new gasket on the oil pan. Many times I do not change the oil pump. Most 6.2 rear main seals I changed were running just fine and only needed a new seal. The original ones were rope seals and I was changing them on 6.2 when these trucks were 6 months old. 1984 was a bad year for GM with rear main seals. 2.8 V6 all bad and leaked also. I would recommend to take your time and clean as you go. Do not cut corners and clean all surfaces well before you reassemble. I hope you find this helpful. If you have any mechanical talent you can do this job. Take your time and be careful. The bolts are all metric on the oil pan. No extra parts when you are done. Good luck.

 

[cpf240]

Sometimes a bad/dirty/clogged CDR valve can cause excess pressure in the crankcase resulting in oil leaking past the rear main seal. The CDR valve can usually be cleaned and reused.

 

[rsh4364]

cucv wiki has a decent write up also.If not a high mileage vehicle would look into what would cause rear main seal leak first,bad cdr.Or something like I did,I installed a 14x7 open element air filter,which eliminated vacuum at idle and allowed my seals to dump oil at idle.Once I swapped back to fact.air filter housing no more leaks.Our air filters require that slight restriction to create vacuum at idle working with the cdr valve.

 

[jpg]

Appears I have a leaking rear bearing seal.
...
Any suggestions and opinion?

My M1010 leaked a quart every 100 miles when I got it.

The 6.2l engine seals depend on maintaining a slight vacuum in the crankcase. To maintain this vacuum, it depends on a good seal at the oil fill cap and the oil dipstick. It also requires a properly functioning CDR valve, and no cracks in the vacuum lines. There are SS threads on this, which is where I learned about it. You can clean your CDR if you don't replace it.

I thought I'd need new seals, but replacing the old, cracked vacuum lines, the CDR, and the oil cap solved my problem. My truck leaked 6 quarts in 600 miles before that, and hasn't leaked a drop in the 3,000 miles since.

I'm not saying you don't need new seals. You might. But even new seals will leak without the proper vacuum. Oil cap, CDR, and vacuum lines are cheap parts. I'd be sure they're sound before I decided I needed new seals.

 

[cucvrus]

If it were me and I had a rear main seal that leaked I would change it while you are indecisive about it. It leaks and regardless of why or how it leaks or leaked it did fail and leak. So change the seal and then make the other changes suggested here to assure it will not leak again. Because dollar to donuts it will leak again and probably in the middle of a trip or the middle of the worst ice age winter you are ever experiencing. When a seal leaks it has failed. Just because it stopped leaking for the time being does not mean it has miraculously healed itself. That does not happen in the real world. Don't add seal fixer or and other additive to prevent oil leaks. That is just a band-aid to the real problem. It would be interesting to know if it still has the old rope seal. Look at changing the seal as a major improvement in your CUCV. A chance to get up in there and clean everything real nice and paint the parts all pretty. Make it easier. I am sure the front springs need bushings also. So I done this before. Pull the front axle, support the vehicle on blocks and go at it. Change the spring bushings the sway bar bushings and the rear main seal. Then wash everything up paint everything up front there and reassemble it. 1 weekend job if you stick at it. A helper would be handy also. Do it right the first time and avoid continuous rework. Good luck to all that had a seal that used to leak and stopped leaking.

 

[Jozseph]

My M1010 leaked a quart every 100 miles when I got it.

The 6.2l engine seals depend on maintaining a slight vacuum in the crankcase. To maintain this vacuum, it depends on a good seal at the oil fill cap and the oil dipstick. It also requires a properly functioning CDR valve, and no cracks in the vacuum lines. There are SS threads on this, which is where I learned about it. You can clean your CDR if you don't replace it.

I thought I'd need new seals, but replacing the old, cracked vacuum lines, the CDR, and the oil cap solved my problem. My truck leaked 6 quarts in 600 miles before that, and hasn't leaked a drop in the 3,000 miles since.

I'm not saying you don't need new seals. You might. But even new seals will leak without the proper vacuum. Oil cap, CDR, and vacuum lines are cheap parts. I'd be sure they're sound before I decided I needed new seals.

JPG, Thank You!

I placed a new air filter and inverted the cover to allow 360 degree all round open air.

Put the air cleaner back to normal, the oil leaking stopped.

 

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JPG, Thank You!

I placed a new air filter and inverted the cover to allow 360 degree all round open air.

Put the air cleaner back to normal, the oil leaking stopped.

Happy to help. Note that I just repeated stuff I learned here on SS.

I also note that cucvrus has 30 years more experience with this than I do. You won't find me arguing against his recommendations. I lack the confidence to take on as many simultaneous tasks as he does, though. I am learning, but I remain a newbie.

It takes a village to maintain these MVs.