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So many different options on rear main seals

Posted By: 1930

So many different options on rear main seals - 04/29/17 02:02 PM

Getting ready to assemble a 440, want to do everything I can to not have any issues with rear main seal, I found a thread on this site where these http://www.dvorakmachine.com/rearmainseal.shtml were recommended but the thread was from 2009.

Any better suggestions?
Posted By: RapidRobert

Re: So many different options on rear main seals - 04/29/17 04:54 PM

I agree rear main leaks are the cats' ass. I would get the surfaces squeaky clean with brake kleen & some silicone under the seal halves and a drop where the seal halves meet each other & also goop the sticks on the sides before installation & you might offset the seal halves 1/4". & as you know but just a reminder, the seal lip toward the oil. You'll be fine. Others will chime in with more info.
Posted By: roadhazard

Re: So many different options on rear main seals - 04/29/17 05:05 PM

Originally Posted By RapidRobert
I agree rear main leaks are the cats' ass. I would get the surfaces squeaky clean with brake kleen & some silicone under the seal halves and a drop where the seal halves meet each other & also goop the sticks on the sides before installation & you might offset the seal halves 1/4". & as you know but just a reminder, the seal lip toward the oil. You'll be fine. Others will chime in with more info.



This right here is where the problems start RR.... all kinds of bad info.

http://www.manciniracing.com/subheporemas.html
Posted By: 6PakBee

Re: So many different options on rear main seals - 04/29/17 05:07 PM

Originally Posted By roadhazard
This right here is where the problems start RR.... all kinds of bad info.

http://www.manciniracing.com/subheporemas.html


I don't understand your point. Please elaborate.
Posted By: RapidRobert

Re: So many different options on rear main seals - 04/29/17 05:23 PM

Me too, I was wondering if my posted info was off. EDIT After rereading it sure sounds like he is saying some or all of my info is off. I can say that that plan has worked for me in the past but if something is off or borderline off let me (us) know & I have a 451 in the works & I too want it right (no leaks).
Posted By: roadhazard

Re: So many different options on rear main seals - 04/29/17 05:31 PM

Originally Posted By 6PakBee
Originally Posted By roadhazard
This right here is where the problems start RR.... all kinds of bad info.

http://www.manciniracing.com/subheporemas.html


I don't understand your point. Please elaborate.


You start putting sillycone on the rear main seal and you have already lost the battle. Never, EVER use that stuff on a rear main seal.

The very first consideration BEFORE a rear main seal goes in is dimensions of the seal groove, it must be on size and Round.

Secondly the rear seal retainer should be aligned with the groove in the block and a reference mark scribed on the pan rail surface for assembly. Alignment of the two seal halves is critical.

3rd, check the crank for dimension and surface finish. Knurling on some of the aftermarket cranks is way to aggressive from what I have seen. Never had an issue with a stock crank, knurled or not.

The point is, do your due diligence BEFORE slapping a seal in and slathering it with sillycone.

I posted a link for a seal that I have intimate knowledge on for nearly 30 years. If it leaks.... it won't be the seal.
Posted By: Sxrxrnr

Re: So many different options on rear main seals - 04/29/17 05:32 PM

Be certain if using new pan bolts from certain vendors that the 2 bolts at rear of pan into retainer, do not bottom out before pan cinches to engine thereby leaving you with a pan gasket leak at this location that may confuse you into believing that your rear main is leaking.
Posted By: 71birdJ68

Re: So many different options on rear main seals - 04/29/17 05:37 PM

Just wondering out loud, but why doesn't someone come up with a one pice seal like we put in the nose if airplane engines. You stretch it around the flag and then glue into the case, and they don't leak.
Posted By: RapidRobert

Re: So many different options on rear main seals - 04/29/17 05:38 PM

Alright, on my 451 I will not use silicone.
Posted By: roadhazard

Re: So many different options on rear main seals - 04/29/17 05:48 PM

Originally Posted By 71birdJ68
Just wondering out loud, but why doesn't someone come up with a one pice seal like we put in the nose if airplane engines. You stretch it around the flag and then glue into the case, and they don't leak.


My best educated guess is the flange on the back of the crank is to large compared to the seal I.D. and stretching a Polyacrylate or Fluoroelastomer (Viton) seal much if at all would prove very difficult IMO.
Not to mention the damage that can occur to the seal dragging it across the flange.
Posted By: John_Kunkel

Re: So many different options on rear main seals - 04/29/17 06:48 PM

Originally Posted By 71birdJ68
Just wondering out loud, but why doesn't someone come up with a one pice seal like we put in the nose if airplane engines. You stretch it around the flag and then glue into the case, and they don't leak.


They do make a one-piece seal but it's not intended to stretch over the flange although I don't see why you couldn't considering that all SAE prop flanges are larger than the Mopar.

http://www.fastfishautoparts.com/Performance-Engine-Seals.html
Posted By: 6PakBee

Re: So many different options on rear main seals - 04/29/17 07:08 PM

Originally Posted By John_Kunkel
Originally Posted By 71birdJ68
Just wondering out loud, but why doesn't someone come up with a one pice seal like we put in the nose if airplane engines. You stretch it around the flag and then glue into the case, and they don't leak.


They do make a one-piece seal but it's not intended to stretch over the flange although I don't see why you couldn't considering that all SAE prop flanges are larger than the Mopar.

http://www.fastfishautoparts.com/Performance-Engine-Seals.html


Wow! That would be worth buying just to try it. John, where do you dig this minutia up?
Posted By: 71birdJ68

Re: So many different options on rear main seals - 04/29/17 09:56 PM

Airplane crank flings are much larger than car flanges. There is a special tool to stretch, and walk it on with. What we do is warm up the seal, and unhook the spring ends, then walk it over the flange. After a little while it shrinks back to size, we hook the spring back together and using contact cement push it into its place in the case. Sometime we take a razor, and slice it to get it around the flange.
Just wondering if this could be considered.
Posted By: dogdays

Re: So many different options on rear main seals - 05/01/17 07:31 PM

So the airplane seal is spring loaded?

When I took apart my first engine that had a one piece rear seal I was amazed at how easy it was to use, and wondered what took American car manufacturers so long to figure it out?

I believe the one piece seal that is already on the market is intended to be cut and then glued back together, probably with a drop of Superglue.

R.
Posted By: Cab_Burge

Re: So many different options on rear main seals - 05/01/17 07:50 PM

I use the stock Mopar or Fel Pro rear main seal kits with "Adhesive Sealant" type gasket maker on the front label, not any other type tsk I use a small dab on the mating ends of both seal and the seal holder and follow the directions on the instruction sheet for the side seals and then wait 24 hrs. for the mineral spirits to soak in and run off. I use a small thin bladed screw driver to use the adhesive sealant to fill and seal up the V joint between the rear main seal holder and the block flush with both sides on both sides as well as the bottom of the seal holder to the block thumbs scope
DO NOT use regular automotive silicone gasket maker for this tsk Adhesive Sealant type only!
Posted By: 71birdJ68

Re: So many different options on rear main seals - 05/01/17 08:08 PM

Yes, there is a small spring that goes all the way around the sealing lip on most airplane flange seals. I think it holds the lip with pressure.
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