What to use for a rear main seal in Olds 350
Thread Starter
Registered User
Joined: Feb 2018
Posts: 91
From: Toledo, Ohio
What to use for a rear main seal in Olds 350
The gasket kit I bought came with rope seals that didn't fit in the grooves. I've looked online and saw something about using rubber seals from other engine. What is the best thing to use?
Thread Starter
Registered User
Joined: Feb 2018
Posts: 91
From: Toledo, Ohio
What to use for a rear main seal in Olds 350
The gasket kit I bought came with rope seals that didn't fit in the grooves. I've looked online and saw something about using rubber seals from other engine. What is the best thing to use?
Registered User
Joined: Sep 2011
Posts: 2,148
From: Plano, TX
Or to make life simpler: felpro BS6141
I can't remember if that's the one that needs to be trimmed or not. If it has little wings coming off the round part of the seal - cut them off. Throw away the straight pieces that come with it.
Make sure the lip "opens" into the engine - that is, as oil comes from the engine trying to get past the seal it'll get caught in the cavity in the lip.
Offset the seal from the cap - put the one in the block rotated a bit so some of it sticks out (maybe 1/8" to 1/4") and turn the one in the cap similarly. Put a SMALL dab of RTV where the two seals meet each other.
Grab some emery cloth and smooth down the RIDGES on the crank where the seal rides. You're not trying to remove them, just knock down any edges. Same type of motion when cleaning copper for sweating. Sometimes those ridges are pretty sharp and will tear up a rubber seal.
I can't remember if that's the one that needs to be trimmed or not. If it has little wings coming off the round part of the seal - cut them off. Throw away the straight pieces that come with it.
Make sure the lip "opens" into the engine - that is, as oil comes from the engine trying to get past the seal it'll get caught in the cavity in the lip.
Offset the seal from the cap - put the one in the block rotated a bit so some of it sticks out (maybe 1/8" to 1/4") and turn the one in the cap similarly. Put a SMALL dab of RTV where the two seals meet each other.
Grab some emery cloth and smooth down the RIDGES on the crank where the seal rides. You're not trying to remove them, just knock down any edges. Same type of motion when cleaning copper for sweating. Sometimes those ridges are pretty sharp and will tear up a rubber seal.
Old(s) Fart
Joined: Mar 2007
Posts: 50,802
From: Northern VA
Registered User
Joined: Dec 2016
Posts: 1,979
From: Beautiful Southern Maryland
I am just going to add that you really need to check the fit of the seal no matter what. I have had them where I had to trim them slightly and then the one in my Wife's 307 that fit perfectly. The blocks were machined for the rope seal which does not need as precise a groove as the rubber seal.
Also, see if you can get your machine shop to hit the crankshaft seal surface with a polishing belt and try to smooth it of as much as possible. You can do it by hand but the crank polishing belt does a much better job. If you do it by hand try to only go in one direction, against the crank rotation. In other words hold the polishing cloth still and rotate the crankshaft in its normal rotating direction.
Also, see if you can get your machine shop to hit the crankshaft seal surface with a polishing belt and try to smooth it of as much as possible. You can do it by hand but the crank polishing belt does a much better job. If you do it by hand try to only go in one direction, against the crank rotation. In other words hold the polishing cloth still and rotate the crankshaft in its normal rotating direction.
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