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Looking for the right rear main seal kit.

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robertf

Active Member
Joined
Mar 21, 2014
Messages
853
So my rear main has been replace a few times over the years. Always Felpro. I see Weber has a Cometic rear main seal. Anything special about these? Of course the leak is very slow but it does stink and I'd like to get it right once and for all, if thats even possible. Thanks.
 
Now come on you world class master tech performance inspector...tell us the proper way, and the best quality parts to fix it! At least for a little while :D
 
i am no master tech, in fact i have had absolutely no training at all in the automotive field. all i have is 20 years of dealing with my own turbo buicks. That being said, i have found that most of my rear mail seal leaks have been from not sealing the main cap to block mating surfaces/side seals and not the rear main seal itself (assuming that it is not the rope seal). Great Stuff silicone seals those ares up perfectly.
 
Crank still has hash marks? Some aftermarket cranks don't have it!

Install the seal per instructions, fill sides of rear cap, not under cap with rtv. No leaks

I would check pcv valve, possibly you guys are putting pressure into oil pan

Just a friendly suggestion
 
I use this one from autozone and Permatex clear RTV to fill the side cavities instead of using the pieces that come with the kit. Just a smear layer of the RTV between the rear main cap and the block. I let it sit for about a week before i add any oil to the engine. I've done a few of these engines over the years like this and never had any leaks. The last one i did in my car now was about 6 years ago and still no leaks. Make sure everything is clean,oil free and dry before you install the seal and RTV.

http://www.autozone.com/internal-en...l-sfi-ohv-turbo/67879_124565_0/?checkfit=true

Here is a link for the procedure to replace the seal. I follow it but with the exceptions i stated above.

http://www.gnttype.org/techarea/engine/rearmain.htm

This link doesn't work so you will have to go to the site and look it up if you want to read it.
 
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Excellent advice. Never thought of tossing the rubber strips for silicone.

When / if you do use the RTV to fill the side cavities continue doing so until it squeezes out of the cracks between the rear main cap and the block,you need to see that happen before you stop filling the cavities. Then wipe off the excess and let it dry / cure for as long as you possibly can before adding oil to the engine and running it. Like i mentioned above i let it sit about 5 days,this may be excessive but my goal is to not have any oil leaks and it works.
 
When / if you do use the RTV to fill the side cavities continue doing so until it squeezes out of the cracks between the rear main cap and the block,you need to see that happen before you stop filling the cavities. Then wipe off the excess and let it dry / cure for as long as you possibly can before adding oil to the engine and running it. Like i mentioned above i let it sit about 5 days,this may be excessive but my goal is to not have any oil leaks and it works.
Will do.
 
The trick with the rear main in threefold. first you put the seal in the bore 'cockeyed' where one face is below flush and the other is above. Put a SMALL dab of sealant on the ends to seal the two halves together. Then smear a 2 molecule thick line of sealant (I use Yamabond5) on the back of the block at the main saddle.

On the side, the right stuff works good. It's very thick and dries pretty tough. Anything thinner like normal RTV needs something like a pipecleaner shoved in there to act like rebar.
 
Ya know Earl, I don't recall ever putting them in cockeye'd. That could possibly be my main issue. I'll assume Yamabond5 is at my local Yamaha motorcycle dealer?
 
I've never done them cock eyed either, I also use right stuff

Anyone have issues when they don't go cock eyed on the rear seal?
 
Forged crank with no knurls, always leaked a little even with the "Right Stuff" in the side grooves. I offset the seal halves 1/4". No more leaks.
 
I used the right stuff also and did it for the 1st time with the motor in the car .cleaned all surface with acetone then applied the rightstuff on block and cap mating surface make sure you put alittle oil on the seal channel so it will slide in easy put the cap on some guys like to cock the seal in other words not install it flush .that's the way I did it then torque to 100lbs then take the right suff and fill the side channels till you see it oozing out the side of the cap and block then slowly pull the tip out of the cavity still applying pressure so its still filling the cavity. I never did this before .it worked like a charm .no leaks.
 
Ya know Earl, I don't recall ever putting them in cockeye'd. That could possibly be my main issue. I'll assume Yamabond5 is at my local Yamaha motorcycle dealer?

As long they're worth a crap. Get a tube of Yamabond4 and Yamabond5.

You'll never be able to live without them as soon as you put hands on them.
 
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