I guess I'll start this one off. Chevy has had lots of problems with rear mains leaking since day one. I did many years working as a heavy line tech in several dealers. from axles to tranmissions to engines, with an occasional "fix those lights/gauges/windows/whatever" thrown in. Anyway, here's a good fix for the 2 piece rear main seals on small blocks and big blocks. There are a couple different seals for the SB as I describe in the following. Not sure about the BB's 100%..

Once you have the pan down, remove the oil pump and pickup. Remove the rear main cap. The lower half of the seal is right there. Don't scratch the bearing. Take a small screwdriver and pop the lower half out of the cap, then use the screwdriver, (I have one that I did a little bit of grinding on so it's got a better flat end) and push on the exposed end of the upper half of the seal. You may hve to tap it a little bit to break the upper seal loose. Drive it out until you can get a good grip on it and then just walk it on out. Now the old seal is out, clean the block and the seal groove with something like brake cleaner, just hose it out really well.

The trick part is next. GM and the aftermarket have 3 different widths of rear seals. The difference in them is from the dust lip on the back to the wiper lip on the forward side of the seal. The best (and widest one) is the one you need to find. The biggest distance between the two lips. You may have to hunt for it. GM had them all under the same part number, but there are different ones.


Take the rear main cap to your bench grinder and use the wire wheel on the mating surfaces adjacent to the seal. Don't get so far forward to catch the bearing. Buff the cap, get it really clean. Then hose it down with the brake cleaner too. Let it dry while you install the upper half of the seal.

In the package there is a little plastic "spoon". Use it to install BOTH the upper and lower halves. Put a little bit of grease on the lips of the upper seal. If you don't, the rib on the inside of the seal gets sliced off and will seep underneath the seal.

Once you have the lower seal in place, wipe a little bit of grease on the lips of that seal too. Apply a very thin coat of form-a-gasket or an anerobic sealer or something like that on the cap next to the seal. Just above the pan gasket groove. Install the cap, torque to specs and install the oil pump, and pan.

I've done literally hundreds of rear main seals over 15+ years of working for Chevy dealers and NEVER had to do the same one twice.

I hope this helps and I also hope I didn't confuse the issue for you. If you have any questions, just drop me a note..

that's cool stuff.

Thankfully, both of our vettes have 1 piece rear mains... but they still weap after a while...

Tim,
Glad to see you here. Good information as usual.

Tim is a good mechanic, and a good friend.

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Hi BIRD :tongue: Yeah Tim knows his stuff

Hi ALL!!!

Hey Deputy! How are things in NM??

For you sb guys with a 2 piece seal,here is the fel-pro part# BS 11829-1 you will want to use,it had the bigger lip on it

This product was Tim approved

dude, you flunked typing 101. No part number in your post! :sign6:

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Hi Tim. Good to see you. Things are okay here.

kwplot forgot to put the part number in his post I found it
Fel-Pro BS 11829-1.


Deputy- things are good. I'm in Atlanta right now, heading for Tulsa tomorrow, Sunday to Las Vegas for the next week, then home, turning right around for the Bird thing in SoCal. I'm going to pickup I-40 around Tucumcari and buzz out that way. I'll have the Vette in the trailer so it won't be a real fast trip.

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I think's my pain pill's must have kicked in at that time but all fixed now

I'm saving this one... may do mine this week, or may say to hell with it and put it off until I do the whole motor.

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Kevin, youre still on the pills? You should send them to me, I will "dispose" of them for you

Kevin: Don't feel bad. I am on some cold pills trying to shake this damn bug that I caught. Half the time I can't even remember my own name :tongue:

Tim: Hope the weather holds up for your trip. Looking nice outside right now

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I'm doing a pretty good job of disposing of them myself, the back is getting better though and i don't take as many as i use too. but physical therapy will start soon and i'm sure the consumption rate will go back up

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I wish that was my problem,had back surgery 4 weeks ago and had 4 rods,6 bolts,and 3 disk added to my lower back,but the doc sent me home with a couple diffrent pain pills,all i can say is oh WOW when i take them

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Ouch!!!! Sounds like you are Steve Austin...the 6 Million Dollar Man... stronger....faster....better.

Except with him it's more like the $6.00 man..