How much rear main seal oil loss is considered normal for our cars?

[Nismobishi]

Did you polish off the 'lines' that helped hold a little bit of oil to lubricate the original rope seal? If not, the lip seal is going to leak....

I did not. Please tell me more about this!

 

[4406bbl]

Did you polish off the 'lines' that helped hold a little bit of oil to lubricate the original rope seal? If not, the lip seal is going to leak....

There is some truth to this, when chrysler built the 360 no rope seals were used and the crank had lines narrower so the seal had a smooth surface. The problem with some big blocks is how the groove is machined in the block. It is usually on the passenger side that the seal is barely touching the crank because the groove is too deep I assume. In the 70s with a MOPAR neoprene seal I never had a leaker, now with the red/brown Vinton seal I have had 2. The fix in my case was to pull the crank, install the seal and retainer, then you see the problem. In both cases the lips on the 2 seal ends were out of alignment by
.020, the fix was when installing pry the passenger side forward by that .020. This is why a fastfish seal fixs a lot of them because with the seal cut in the retainer it guides the retainer into alignment. Some still leak because the groove in the block just does not let the seal touch the crank enough, usually on the passenger side so far for me. I have fixed that by epoxying some
.010-.020 shim material in the groove, and offsetting the seal about a quarter turn. When you remove the crank and look close, it all becomes clear. I also never put in a seal and trust it, it is always engine on blocks with crank pointing down, pour oil in, it should not leak.....when you do this you will see it is always where the seal meets the crank, usually near the crank parting line, usually passenger side. A .020 fatter seal would fix this, but maybe that would not last in the engine, but it sure looks to me like the 440 seals are not as tight to the crank as the 360 seal. The pics show the narrowed lines of the seal area of a 360 crank, for which a rope seal was never used.

 

[4406bbl]

On this block the drivers side of the retainer needed to be flush with the back of the block for perfect alignment, and moved .020 forward to align on the passenger side. No way to know this in car. The retainer slides a lot, always offset the seal in problem blocks if changing in the car or use the fastfish seal, or a rope. The rear main cap should also be slide forward until the relief groove lines up, so the seal retainer can move forward as needed. Polishing the grooves all the way our will guarantee a leak as the crank will be substantially smaller, maybe a slight polish and fill the grooves with epoxy/ jb weld.

 

[R413]

It all this mystery surrounding it, and 3 page long threads With all these “must do items”. I think this causes leaks, just put the seal in and don’t make a big thing about it.

i use fel-pro rubber seals and I don’t do anything to the grooves on the crank, seals fine with no leaks.

 

[Nismobishi]

It all this mystery surrounding it, and 3 page long threads With all these “must do items”. I think this causes leaks, just put the seal in and don’t make a big thing about it.

i use fel-pro rubber seals and I don’t do anything to the grooves on the crank, seals fine with no leaks.

Honestly, I think my silicone job on the base of the cap or the side seals has a small leak. I don't think it's the seal itself. I'm just going to redo it but instead of using of the side seals I will pump silicone into the side channels until it comes out of the seams.

 

[HawkRod]

I agree that the side seals are likely the cause of a majority of rear main seal leaks. I personally found it hard to get them installed without them slipping out of the retainer; it took me a couple of tries.

I think the Mancini instructions said it very well: After after you install the retainer, if ANY part of the side seals are sticking up, then STOP - do NOT trim them. Take it out and do it again. The side seals are the exact length they need to be. If you trim the top it means they slid up from the bottom, creating a gap that allows oil to leak.

 

[El.Padrino]

What about the thing to only use a rope seal if the crank has the "knurls"? Or can I use it on a smooth crank as well?

Think of trying the rope seal, had no luck with the 2-piece Viton and no luck with the fastfish seal. I have a smooth crank.

 

[Cranky]

What about the thing to only use a rope seal if the crank has the "knurls"? Or can I use it on a smooth crank as well?

Think of trying the rope seal, had no luck with the 2-piece Viton and no luck with the fastfish seal.

If you're running a viton lip seal, the knurls are not your friend......

 

[El.Padrino]

If you're running a viton lip seal, the knurls are not your friend......

I do not have the knurls

 

[440 PHIXX]

I’ve owned 13 Mopars including my daily here. They all leaked… leak. I’m used to it.

 

[Cranky]

I do not have the knurls

The 'knurls' are actually there to help channel a tiny bit of oil to the packing (rope seal) so it does not burn up. It's to provide a bit of lubrication.

 

[El.Padrino]

The 'knurls' are actually there to help channel a tiny bit of oil to the packing (rope seal) so it does not burn up. It's to provide a bit of lubrication.

I am aware of this, probably not a good idea to try a rope seal on a smooth crank?!

 

[Cranky]

I am aware of this, probably not a good idea to try a rope seal on a smooth crank?!

Never ran one on a totally smooth crank so have no idea how long it may last. I do have some experience with rope seals at a refinery where I worked for 26 years and they started converting to mechanical seals (because of the EPA) but we still had lots of pumps etc that still ran the rope style packing and every pump that had them either had some sort of a lubricant going to them or the product lubed them. Most everything ran at 3600 rpm and if the lube was accidentally turned off or the product lube valve wasn't open enough, it didn't take long for the rope packing to get hot and hard or even catch on fire if the product was flammable. I've even thought about going back to the rope stuff since it worked fine for a lot of years.

 

[khryslerkid]

Sometimes oil can leak past the seal retainer bolt holes if you don't fill them level with sealer. You can see the edge of the holes at the back of your gasket.

(These are not filled level)

 

[dvw]

Drill the seal retainer holes 1/64 oversize. Now if you off set the seal the cap will self align. I fill the side grooves with Ultra-Grey RTV. I also run a very small bead of anerobic sealer between the seal bridge and the block. My racecar has the same red rear seal since 2012. The motor has been freshened 3 times. Same seal, never replaced. Zero leaks from the seal or retainer. As stated in post #34 fill the bolt holes with RTV. I had a slight leak recently. While the trans was out for servive the crank case was sealed and aired up to 5psi. Then the area was sprayed with soapy water. The culprit? Small section of the cam plug. Resealed the plug. No leaks.
Doug

 

[Cranky]

Drill the seal retainer holes 1/64 oversize. Now if you off set the seal the cap will self align. I fill the side grooves with Ultra-Grey RTV. I also run a very small bead of anerobic sealer between the seal bridge and the block. My racecar has the same red rear seal since 2012. The motor has been freshened 3 times. Same seal, never replaced. Zero leaks from the seal or retainer. As stated in post #34 fill the bolt holes with RTV. I had a slight leak recently. While the trans was out for servive the crank case was sealed and aired up to 5psi. Then the area was sprayed with soapy water. The culprit? Small section of the cam plug. Resealed the plug. No leaks.
Doug

Do you used the anerobic sealer in lieu of the strips or with them?

 

[dvw]

Do you used the anerobic sealer in lieu of the strips or with them?

No, the side grooves are filled with RTV. The anerobic is used where the seal bridge surface touches the block. It keeps oil from weeping between the seal bridge and block where it woud normally be metal to metal surface contact. For those who don't know. Anerobic looks like loctite. It provides a very thin seal between metal surfaces that are very smooth. It dries in the absence of air. We used it at the dealership to seal transfer case halves.
Doug

 

[beanhead]

Sometimes oil can leak past the seal retainer bolt holes if you don't fill them level with sealer. You can see the edge of the holes at the back of your gasket.

(These are not filled level)
View attachment 1683153

Yep, thanks 'Kid...and your picture is a good reminder that the two oil pan bolt holes in the retainer are slightly shallower than the holes in the block pan rail.
I've fixed more than one ''rear main leak'' for friends' cars that used too-long bolts there. It's not always apparent at install time because the bolts still appear to tighten down against the oil pan.
And as DVW mentioned above, toss the side seals and just fill the grooves with the proper sealer.

 

[MCODECUDA]

Could be a leaking camshaft plug.

The 440 that was in my Belvedere had an oil leak that I couldn’t stop. I pulled the motor and replaced it. It was setting on my motor stand and one day I noticed oil on the cam plug. I have a new plug but I siliconed it instead. I’m not sure if it will work but I’ll give it a try.

 

[Cranky]

The 440 that was in my Belvedere had an oil leak that I couldn’t stop. I pulled the motor and replaced it. It was setting on my motor stand and one day I noticed oil on the cam plug. I have a new plug but I siliconed it instead. I’m not sure if it will work but I’ll give it a try.

Just make sure it's perfectly clean plus I would try to scuff up the area where you will be putting the sealant. But why not just go ahead and replace the plug??? It's not that hard to do....