How do I trim rubber at rear main to fit the groove

[ljaynavl]

How do I properly cut the squared rubber seal that fits the groove on the rear main bearing? Engine is in the car, so all work is done from underneath.

Is it ok to goop it up with Permatex RTV to help hold it in place when raising the pan up?

[Synchro909]

Getting just the right length is not easy IMO. I hold the strip so that one corner of it is in the groove, then using a fine blade to guide in the other corner, I push it in starting at one end and work towards the other. Needless to say, the first end is easy to get right by holding the strip against the under side of the block when you start. When you are close to the other end, things are not so simple. As you push the strip into the groove, the diameter changes and you will need slightly less than you'd think but don't cut it too short (easily done) and don't leave it too long (easily done). You may have to do a little trial and error adjustment. What ever you do, you'll need a dab of silicone in the corner when you refit the sump. I don't use any "goop" under it. It is a tight enough fit in he groove that it will stay there while you refit the sump.
All that said, why not remove the bearing cap from the engine altogether and do it properly on the workbench? It doesn't have to be done in the car. Unless you have a counterweighted crank, it is easy. Just make sure cylinder #4 is near the top of its stroke and the cap can be wiggled out after pushing the bolts up a bit (not too far). I have done it lots of times.
I put a piece of rag in the flywheel housing in case I drop something so that it doesn't get lost in there. To undo the nut holding the bearing cap, you'll need a long socket handle with a small pivot joint. Most of the modern tools are not made of good enough quality steel which means they are chunky to have the strength. That means you won't be able to get themin there especially when the nut is getting lower. Good older tools are better quality steel and smaller dimensions. I don't know the American market in tools so I can't suggest which brand might be best. I use and Australian made "Sidchrome" breaker bar from about the 1970s. Later Sidchrome tools are made in China and suffer the condition mentioned above.

[old ugly]

i use the trial and error method and once its in there i use a bit of good silicone seal at the point the gasket meets the square bearing cap gasket. not too much just enough to fill the end gaps.

usually having good success

[BRENT in 10-uh-C]

Originally Posted by ljaynavl

How do I properly cut the squared rubber seal that fits the groove on the rear main bearing? Engine is in the car, so all work is done from underneath.

Is it ok to goop it up with Permatex RTV to help hold it in place when raising the pan up?

Help me out here, ...where is there a rubber seal? You really should be using Cork.

The best way on a Cork seal is to clamp the Cork seal in a vise and compress it for a few minutes. Then quickly insert it into the channel on the Rear Main Cap before it expands back to its regular size. Once installed, then add some Permatex sealer to the voids.

[larrys40]

Jay,Brent and all…
I’ll go ahead and throw my 2 cents worth in. As Brent said use cork!! Make sure old channel is clean and oil free. I use a dull flat blade screw driver to push one side in while the other side of the cork is against the cap. Work all the way around. It must be seated well. When you get the the other side it’s an experience and thing I guess but you can judge easily on cutting the length off. I use a razor blade and it’s a pretty easy call. After in place I take a small ball pien hammer ( flat end ) and gently tap the cork flat all the way around. It helps to seat it and make it flat for pan install. Use a little rtv at the ends prior to putting the pan up.
I never have a problem.
On a side note , I would NEVER remove a cap to put the cork seal on. Not sure why you would go through those motions and risk if not necessary.
Just saying…. Last caution is always be careful of the oil tube and make sure it’s clear.
Larry

[Synchro909]

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Some of the seals are made of some composite material that looks like a rubberised cork. I think the ones from Brattons are like that while others are plainly cork. I suspect the OP has a seal from Brattons.

[Dave in MN]

Pre-cut the gasket and use a thin coat of sealant in the rear main cap groove.

When I open a pan gasket set, I precut the cork seal used at the rear cap to exactly 6-7/8" long and place it in a one-pound metal coffee can. Leaving the gasket in the can for several days causes it to take the radius of the container. I always have several of the cork gaskets in the metal can so I am not delayed in installing a pan. The radius imparted to the gasket eliminates the tendency for the gasket to move out of the groove.
I use a light coating of Permatex #2 on the cap and work the gasket into the groove of the rear main cap by pressing the broad side of the gasket with a finger and the side of the gasket with a 5/16" wide screwdriver. Start on one side and work your way around.

See the photos below:
Good Day!

[john charlton]

The coffee can trick is the way to go I put an inch of boiling water in the bottom and "steam" the seal it seams to give a set curve . Make sure you have the correct width seal 28/29 is 13/32" and 30/31 is 3/8" wide . The thicker will not easily sit in the thinner groove .I do not trim any gasket ends on the front and sides I just bolt the whole caboodle up and they sort themselves out no leaks yet

John in sunny morning Chandler AZ