Replacing rear main oil seal

[Mortimer452]

OK, I'm confused.  Engine is a P22.  It leaks oil like hell, about 2 quarts per tank of gas.  I've determined the leaks are from the oil pan gasket, rear main seal and oil pump.

I'm on to replacing the lower rear main seal now, ordered the rope seal kit from Bernbaum.  Pulled the main bearing cap tonight and it's not quite what I expected - there's a rubber seal in there now, seems to be integrated as part of the retainer as seen in pics below.  Did I get the wrong seal?  According to the service manual there should be a rope-type seal in there now but there isn't - it has a retainer like the 1946-1952 pic but has a rubber seal attached like the 1953 pic in the manual.

 

[Dodgeb4ya]

There were a few different types of  MoPar flat head rear main seals used back in the day both from Chrysler ,Victor, McChord and others.

I have seen that style of rear main seal before. See the link below....

To use the rope seal you will need the  factory original two retainer plates as you probably know.

Or buy this set...

http://www.ebay.com/itm/Chrysler-Dodge-201-228-230-251-265-Rubber-Bolt-On-Rear-Main-Seal-Set-BEST-34-60-/171167764871?fits=Year%3A1946|Make%3APlymouth&epid=1029932053&hash=item27da64d187:g:pLwAAMXQAI9SJhAp&vxp=mtr

Edited September 16, 2019 by Dodgeb4ya

[Mortimer452]

Thanks, that's definitely more like the one I have now!  I suppose I should stick with that style since I'm sure the same is on the top half and I'm only replacing the lower one right now, I don't think the top can be replaced without pulling the motor.  Hopefully this plus the pan gasket will solve my oil leaking problem, or at least reduce it enough to where I can drive across town without losing a quart of oil.

Dangit, I was hoping to finish this job over the weekend.

Edited September 9, 2017 by Mortimer452

[Dodgeb4ya]

You better do both!

[Andydodge]

Mortimer...........that's what I found when I did the rear main seal of the 1941 Plymouth I had..........I ordered a rope seal as that's what the manual said it would have..........luckily I had already a complete Best brand gasket set which had both types of neoprene rear seal and both types of "ears" that went on the side of the rear main cap.........when I pulled the pan & rear main cap I found the same neoprene seal as you have but NO "ears"..........lol............the neoprene seal in mine looked fairly new so I left it alone but added the "ears" , cleaned the pan & oil pickup and added new pan gaskets..........it still had a small weep but the adding of the ears made a big improvement............it seems that its a luck dip as to what type of seal these engines have...........lol........andyd   

[busycoupe]

Several years back I had the same problem. I found that my engine had the same kind of seal as yours and that I would have to pull the transmission and fluid drive unit to replace the top half of the seal.  I did not want to tackle that at that time, so I simply replaced the bottom half.  I also discovered that the bolts holding the top half of the seal were loose.  I was able to snug up the bolts with a thin open end wrench.  The new bottom half seal and tightening the bolts solved about 95% of my leak problem.  ... Not perfect, but it has been A problem that I can live with.

[Matt Wilson]

20 hours ago, Mortimer452 said:

Thanks, that's definitely more like the one I have now!  I suppose I should stick with that style since I'm sure the same is on the top half and I'm only replacing the lower one right now, I don't think the top can be replaced without pulling the motor.  Hopefully this plus the pan gasket will solve my oil leaking problem, or at least reduce it enough to where I can drive across town without losing a quart of oil.

Dangit, I was hoping to finish this job over the weekend.

If you don't want to wait for the parts to be shipped, you can get O'Reilly Auto Parts (if you have them in your area) or NAPA to order a Fel-Pro seal that looks just like the one you currently have, and it comes with the gasket to go between the seal halves and the engine, and it also comes with the h-shaped rubber pieces that others talked about, which I believe go between the bearing cap and the block.  The part I ordered, which I THINK fits all the Dodge/Plymouth/Chrysler flatheads is BS6300, or FP BS6300.  NAPA and O'Reilly both claimed they could get the seal either the same day or the next day.  I went with NAPA because their online price was $2 cheaper than O'Reilly's, and I could pick it up at the store that same day (this was last weekend).  As it turns out, I will not be using that bolt-on type of seal, but at least I can pass along this info to you.

Good luck!

Edited September 10, 2017 by Matt Wilson

[Mortimer452]

2 hours ago, Matt Wilson said:

If you don't want to wait for the parts to be shipped, you can get O'Reilly Auto Parts (if you have them in your area) or NAPA to order a Fel-Pro seal that looks just like the one you currently have, and it comes with the gasket to go between the seal halves and the engine, and it also comes with the h-shaped rubber pieces that others talked about, which I believe go between the bearing cap and the block.  The part I ordered, which I THINK fits all the Dodge/Plymouth/Chrysler flatheads is BS6300, or FP BS6300.  NAPA and O'Reilly both claimed they could get the seal either the same day or the next day.  I went with NAPA because their online price was $2 cheaper than O'Reilly's, and I could pick it up at the store that same day (this was last weekend).  As it turns out, I will not be using that bolt-on type of seal, but at least I can pass along this info to you.

Good luck!

THANK YOU!  I'm in luck, there's an O'Reilly's in a neighboring town that has this seal, less than 30 min drive away.  I hate waiting on parts, I have so little time to work on the car lately it really sets things back when I have to order stuff online and wait for it to get here, then wait again for time to do the work.  I may get this done over the weekend yet!

[Matt Wilson]

8 minutes ago, Mortimer452 said:

THANK YOU!  I'm in luck, there's an O'Reilly's in a neighboring town that has this seal, less than 30 min drive away.  I hate waiting on parts, I have so little time to work on the car lately it really sets things back when I have to order stuff online and wait for it to get here, then wait again for time to do the work.  I may get this done over the weekend yet!

Fantastic!  Hopefully you double-checked to be sure that part number fits your engine.  I'm pretty sure it fits all of the flatheads, but I'm not 100% sure.  Glad I could be of help.  Good luck!!

[Mortimer452]

Got 'er put back together finally.  Started it up and let it run for 10 minutes, lifted it back up and couldn't find a drop of oil anywhere.  I'm happy to start driving it again!

Decided to go with the factory recommendation of 30wt non-detergent oil.  That is some thick stuff compared to Quaker State 10w30.  

[Matt Wilson]

Great news!  It's such a nice feeling when stuff like this works out. 

[Stargrinder]

Dang... I was hoping there was a way to change the rear seal (top and bottom).  I just picked up a '50 Coronet that seams to have a rear main seal leak.

 

Any advice anyone can offer before I tear into this thing?

 

Thanks

[Dodgeb4ya]

Pull the trans and flywheel to do both upper and lower....

[tom'sB2B]

[tom'sB2B]

[tom'sB2B]

[Stargrinder]

Tom,

Much appreciated.  That is what I feared.  I think I am going to have to call in an expert as that is most likely outside my level of expertise and I lack the right equipment.

 

Damn...

[Stargrinder]

Well I pulled the oil pan today and found that the previous gasket was completely deteriorated and a portion of the pan near the rear seal was bent. I cleaned the sludge out the pan, streightened the lip of the pan, and put on a new gasket which I know will take care of some of my leak. I tried to remove the rear main bearing to replace the lower half of the main seal but could not remove it because it was hitting the lower bell housing for the transmission. I just could not get it to clear. I thought I would be able to at least access the lower half of the main seal without removing the transmission. Am I missing something?   Any guidance is greatly appreciated. 

Edited May 6, 2020 by Stargrinder

[Stargrinder]

Well I put oil back in her today and took her out for a good run.  I am happy to report that my oil leak has now become just a couple drops from replacing the oil pan gasket.  Once I get the main rear replaced I think I will be golden.

[dalewalt]

Question on this topic... I have an oil seal like is posted by Tom'sB2B above (2 small h-shaped gaskets and two metal retainers).  How are the h-shaped gaskets installed?  I've been looking through the 1940 shop manual I have for this and, for the life of me, cannot figure out how it's supposed to be installed.

 

Are the retainers and the two h-shaped gaskets the entirety of the rear main oil seal?

[Stargrinder]

So here is a question for the old timers ... to replace the rear main requires the transmission to be separated from the motor.  This is a very a very involved task.  However which is the better bet to get it done?  Remove the motor or the transmission?  Looking under the car I don't see how to get the trans out because of the cross-member.  Am I missing something?  

[Sniper]

Depends on what you have, some of our rides have removable floors and you can pull the trans out that way., in the case of my 51 Plymouth you can pull the trans from underneath no

problem.  Now the bell housing is another story. 

[Stargrinder]

Sniper, I have a 50 Coronet.  Not sure if the trans can come up through the floor I never thought about that.  I may need to pull up the floor to look to verify.  However looking at the shop manual it only seems like there may only be an access portal to possibly get to the to bolt of the clutch bell housing.  I know there is a brace across the frame that looks like it is welded in so going down does not seem like much of an option.  Hence why I am scratching my head.  I am just so apprehensive about pulling this damn thing apart.  I am also a bit apprehensive about taking it to a local shop as those that I have gone to so far don't instill a level of confidence in me that they know what they are doing.

 

I am thinking that I might be able to loosen the mounts to the trans and jack it up in the back just enough to get the lower clutch bell housing removed.  That way I can at least replace the lower portion of the rear main oil seal and the cap gaskets between the rear bearing halves. 

 

Sometimes I wish I could just take this car back in time when there were several shops that could do this work.  The knowledge has faded over time.

 

If anyone knows of a good shop near Baltimore or DC I would appreciate the recommendation.

[Sniper]

This guys pulls one out of a 51 Coronet,the first 40 seconds will make you motion sick though.  You realize the trans and bellhousings are bolted together?

 

[Dodgeb4ya]

You really need to remove the heavy GyroMatic  transmission using a transmission jack so you don't end up with a damaged transmission or body! 

A floor jack is a fools way to pull a heavy trans which is what is in your Dodge.

The video proves that?!

So...some tips.

**Remove the lower bell housing cover first...then look up between the fluid drive coupling and the rear main cap to be sure your engine has six small bolts holding the rear main seal plates to the block....if so read the rest of this.

If there are no small bolts retaining the rear main seal plates your rear main seal is inside the engine under the rear main cap....the trans doesn't need to be removed to replace that style of seal....but the oil pan has to come off. Your original engine should have the external type seal though.

So....onward to the next step

**Before pulling out the trans...The FD  clutch driven plate should have four equally spaced small wooden support wedges pushed in by hand  between it and the Fluid Drive coupling to prevent the clutch driven plate from excess lateral movement.

This step protects the internal somewhat delicate bellows seal and graphite seal ring. Now after removing the trans wiring under the pass floor access cover you can pull the transmission straight out...slowly and carefully.

**Next remove the throw out bearing, clutch pressure plate and disc.

**Then the fluid drive coupling needs to be removed....eight nuts bolt it to the crankshaft...a long special wrench generally is used to remove the nuts.

Access is tight.

The fluid coupling is very heavy and awkward to pull off the crank. If you have never pulled one off you better be ready ....it's very heavy...don't drop it.

Now you have some access to the two piece rear main seal...that's another whole story..

Re-doing the rear main seal plates properly with the original asbestos rope would be difficult for a first timer .

The retainer plates have to be spread/opened up. New ropes installed and carefully rolled into the plates....the plates squeezed back semi tight on the rope seals ...assembled seal plates test fitted to the crank for sealing fit and feel.

Maybe two three four times...

Then trim the rope ends just right...

This is a technical job that a lot of care and knowledge is required to have 100% sucess. 

The car needs to be on a lift or jacked up and supported safely.

Then the job is all done! Simple? Naw?

Give it a whirl...have some fun and learn!

Okay I threw my thoughts in..