Just wanted to know if this method is tried and true, or at least really worth it. Taking my car back to the place I got the engine cause the long block has a 1 year/10k mile warranty...and the rear main is leaking.

 

Always.

 

I offset mine about 1/4" every time.

 

I offset at least 1/4" and put a dab of silicone on the ends where the seals touch each other, never had a leak this way. But i still like the modern 1 seal type better.

 

If this is the problem I have I'm going to tell the guys who have to do the warranty work to offset it...cut and dry.

Kinda weird...I asked my engine builder in Hawaii who just finished up my 355 to offset the rear main and he asked why....I said because I don't want it to leak, ever. He said, trust me...it won't leak...no need to offset it.

He's the best guy on the island....he runs a 355 in a S-10 with a Jeff-co trans on the street...bad to the bone. I wonder why he doesn't offset his???

 

Some people you just cant tell anything. My good friend has a dragster, runs a 360 spinning 10K rpms, runs nitro for fuel. some crazy crap...

he helped me build my first motor. when i asked him why he didnt offset the rear-main seals like all the books say, he just laughed.

I still do it though, it cant HURT it can only HELP but, i guess, some people just don't beleive in that sort of thing

 

i always do any more, went years without doing it and never had a problem that i know of, but like was already said it's easy cheap insurance against a potential problem.

 

We've got a hell of a following for offsetting the main seal!!!

BTW: I offset to

Ron

 

The last engine for my car (current engine) I dident offset the RMS, dont know why I dident but the sucker leaks. Its just one of those things you do or dont either way theres always a chance for leaks.

 

I don't. Haven't had a problem. Getting the little dabs of silicone in the right place where the rear main cap meets it's saddle is FAR more important to preventing a leak, in my opinion. In fact, it WILL leak if you don't, period.

 

i also offset on them, but if i wouldn't say it's the only way to do it. either way, much past 40k a two piece rear main seal engine is going to start to seap and develop into a leak. that would be the reason i only use one piece rear main seal blocks when i build something for someone.

 

ok.. newbie question here: What's offsetting the rear main seal? I've seen the rear main seal on my L98, and it's just one big circular piece that doesn't seem like it can be physically manipulated to make it fit differently from where it's supposed to go

 

Im with Newbie...

 

Pre- roller motors ( before 1987) had a rear main seal that was two pieces, not a one piece seal like you have on the L98. The reason they got rid of the 2 piece in favor of the one piece was because they were less prone to oil leakage.

Offsetting the seal mean that instead of installing the rubber seal with one side on top of the crank and one side in the main bearing cap..., you turn the seals in a circular motion in one direction ( clockwise or counter clockwise) so that the ends of each seal are mating on a solid smooth surface. i.e. the joint of the seals will not be where the main cap and block join, it will be actually along the block for one piece of the seal and on the bearing cap for the other.

Hope that all made sense.

 

How do you do this? I don't understand how you would get the seal into the slot of the cap. Do you just slide the seal ends around the crank journal and then put the cap on? Do you still put sealer on the ends of the seal pieces?

 

Instead of sliding it until it is flush, you push it a bit more so that one end is sticking out like 1/2 inch from the block. Then you put a dab of sealer on the ends, and put the main cap on.

 

So if I understand correctly, the seal is not offset 90 degrees(like I was thinking) it is only offset a little bit. Is that right?

 

Thanks for the info guys. I had not heard of this but I will surely offset the RMS from now on.

Thanks again,
George

 

Yes.

IMHO, it doesn't matter where the seams are in relation to the seam of the cap to the block.

Regardless of how where you put the seams, you're still going to have two seams riding the rear journal. That's where oil is going to find it's way out.

Oil doesn't care where it has to go to get out. If there's a way, it'll find it.

Just my 2¢, no flames intended.

 

I gotta agree with :hail: Damon. I put sealer in the harmonic
balancer bore for the same reason.

 

First time I've heard of doing this lol Well, I didn't offset mine. After over 3 years of driving the car, the rear main seal is still dry

 

i agree it's a feel good thing as much as anything. i think the same about priming the oil pump. never do it on SBC and similar designs but on other engines i believe it's a must.

 

Yeah....Ive always off set mine too. Never had any bad leaks so why not.

 

Try the old impregnated rope seals. No matter what you do to them, they'll leak in a couple of years.