Its a factory 66 440 crank and block. It has been align honed. What is the latest and greatest way to keep it from leaking? I have the Felpro gasket set, but will upgrade the rear seal based on recommendations here.

This is a street car.

Thanks,

nd65

nd.neal@gmail.com

Lots of threads on this topic here. And lots of opinions on what procedure is best. Have you tried a search?

Yes, done a search. Thought perhaps there would be newer info or opinions on this.

I used the Fast Fish one piece seal and no side seals only silicone after having leaks with 2 different conventional 2 piece seal and 2 different types of side seals. No more leaks with the one piece seal. David Barton had recommended the one piece seal and said they use it themselves when they have a problem making one seal up. I purchased mine from them. Installation would be easier when your installing the crank initially before you have rods and pistons attached but it can be done as an after thought.

Can you explain how this one piece seal is installed? is it stretched over the crank hub and shrinks back to proper size? Or is it just one long straight piece of rubber seal cut to size?

It comes as a 1 piece circle, you make one cut install it then glue the 2 ends together after it's on the crank. Then you slip the seal retainer over top of it. I don't have any pictures before I cut it or with it glued but I've included a picture with it on the crank. I'm not 100% certain that my leak was resolved from the one piece crank seal or from leaving the side seals out and letting the retainer locate itself with the crank seal as opposed to the side seals.

JCC, do you just put silicone where the side seals normally go?

Yes, I used Permatex Ultra Black.

There was another thread about leaking rear seals , maybe more but in one of them I stated that I had been rebuilding big block mopars since the early 70's and never had a leak. Well I never should have said anything as the one I just put together this week is leaking. Crap. I don't think it is the actual crank seal but the plastic retainer side sticks. They should have suck with the old cardboard ones.

I'm looking to place an order for a rear seal soon and was wondering about this as well. How well do the old rope seals work?

Cool idea...

Got me to thinking, couldn't you use a stock 2 piece seal with both halves turned 90 degrees and get similar results?

Put grease on crank to hold both halves in place then carefully set the crank in.

Of course you couldn't install it with crank already in the block.

Just thinking out loud.

You shouldn't have any trouble with a factory crank since it will have the correct knurling on it. Some aftermarket cranks are knurled and some are smooth. With the smooth ones you need to be careful on which seal you use. I think the choices are more limited now on the rear main seals.

Andy brings up a very good point regarding the knurling on a stock crank. My Ohio Crankshaft did not have that feature and that definitely could have contributed to my leak.

I don't see a problem with doing that but I also don't believe that the main seal is the cause of the majority of the leaks. It's the side seals, either to loose or you have to pound them in.

I appreciate the replies. It sounds like with a stock crank sealing should not be an issue.

The rope seals are a PITA to cut, I used a rope one and rubber side seals and mine is leaking. I really did not like the rubber side seals, I will fill them with RTV next time as much as I don't like that idea either.

Monte Smith had what I thought was a very good suggestion, and I'm going to try this when I try to fix mine. His point was that it is really the side seals or the retainer being off that cause the rear main to leak, because they force the seal to fit too tightly or loose on either side of the crank. He suggested clocking the seal 90 degrees so that the parting line is at the top and bottom (in place on the crank) and then setting the retainer in place, taking care to make sure it was centered around the crank seal and distributing pressure evenly. If necessary you may need to oblong the holes for the bolts. Insert the bolts and lock them down, then fill the sides with RTV.

I thought the instructions with the rear mains seals specifically stated to do this. I think I clocked my last one 45* instead of 90, but the idea is the same, to have a solid, continuous groove center the halves of the seal. I think next time I will try rtv instead of the "soak em in solvent and squish them quickly while trying to not [censored] them up and scrape too much cardboard off" side seals.

Thx for touching on the rope seal GTX MATT, sounds like they're not worth considering. I'll probably go with a seal kit from member RoadHazard. Whats been everyone's luck with the rubber side seals? I'd think those used with a good silicone would sell up the sides of the retainer pretty good

The side seal strips have to be DRY, no oil, when installed. Put a dab of black sealer on the ends, make sure retainer is square, like a main cap is done and the end strips will expand once oil hits them. The neoprene circle seals don't line up with the knurl any way, would eat it up. Oil dissolves silicone, it will release from the surfaces after awile = oil leak.

i use the stock stuff. i think sometimes folks think the main is leaking and it's actually the back of the pan or the oil is migrating down from a valve cover or intake gasket.

I used the fel-pro that came w/my gasket set and slightly off set em w/a dab of silicone on the ends then install the sides dry. Then I fill the cavity on each side from top to bottom w/silicone on the outside of the retainer and let cure for a few days............

I covered in another thread on this issue, that I think seldom is the problem the crank OR the seal. It's the seal retainer. The retainer is just a cast and not precision machined piece. I have also seen some variance in the holes in the block for the retainer. If the bolts in any way, shape or form, pull the retainer to one side or cock it, you WILL have a leak and no seal or amount of silicone is going to fix it. The nicely machined aftermarket ones are great, provided the holes in the block are perfect.

During mockup, I always install crank, seal and then drop retainer on dry seal and seat it. Now look in the holes. If it looks like the bolt is going to influence the retainer in any direction, you WILL have a leak. So you try another retainer, or open the holes up. Now the next one I build may leak like a sieve, but I haven't had a big block rear main leak in years using this method. I also don't use the side seals, as they can push the retainer over. I use silicone. I also don't glue the seal in the block or cap. I put it in dry and clock the seal ends 90* from parting line on retainer

Chevy rear seals don't leak because the seal is contained in the rear cap and always properly located and clamped. The BBM seal arrangement looks like an after thought and often acts that way. Its the retainer

Monte, what kind of silicone do you use?

Usually Ultra-Black...........but if I am out, whatever I have........LOL!!!

Oil does not dissolve the RIGHT silicone. Cars come from the factory with silicone gaskets in some applications.

what about the billet rear main séal kit from Mancini or 440source are they good ?

All silicone, some just resist it more. If in contact with oil or gas it's neopreme

I haven't used a gasket on an oil pan, a rear seal retainer, on the china walls and several others places in years and years. I don't have leaks. You CAN'T have leaks on a motor and it make vacuum. And I have no problem with that. Our 738 Nitrous motor doesn't have a gasket in it other than heads, valve covers and intake. Makes 19" of vacuum and doesn't leak a drop. Your mileage may vary

I think some people are thinking silicone that is used to seal your house cracks. Were talking about automotive gasket adhesive or gasket maker.

I like the Orange 2 piece seals from Hughes or Mancini. I built 3 BB
Mopars last year with none of them leaking and no customer complaints. I like to line up the seals before the crank is installed. Once the parting lines on both the upper and lower seals are aligned, I scribe a reference line across the seal holder and oil pan rail. Keep in mind, there is play in that seal holder so if you install it without any alignment reference your new engine will leak.