Author Topic: '28 Rear Main Seal  (Read 1622 times)

SteveG

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'28 Rear Main Seal
« on: April 28, 2014, 10:46:21 PM »
Oil is dripping from the drain hole at the bottom of the bell housing. It leaks about a Quart every 100/150 miles.

I tightened down the pressure adjustment at last oil change. Perhaps too much. I run a steady 20 lbs. oil pressure.

I think the rear mail seal needs new.

I was told that I might be able to change it out by dropping the pan. He referred to the seal as a "dog turd", and I may be to change it that way.

Am I headed in the right direction?

Any comments and further information is appreciated.

Thanx.

SteveG

29UJohn

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Re: '28 Rear Main Seal
« Reply #1 on: May 17, 2014, 03:19:32 PM »
A leaking rear main seal does not have anything to do with the oil pressure. 

I am not very familiar with the 28 engine.  The 29 uses a rope seal mounted in a bracket on the outside of the engine, but I have also seen a cork seal in one.  I have changed the rear main rope seal on my 29 without pulling the engine, but it was a bit more involved than just dropping the pan.  Supposedly you can remove the rear main cap, push out the top half seal, and using a tool called a Chinese Finger, insert the new top half seal.  Then replace the bottom half and replace the cap.  But, it really isn't so easy.  I had to remove the tranny and flywheel, loosen all the main caps, drop the crank a little, remove the rear main cap and then remove the upper seal bracket.  Not a fun job.

Most all these old cars leak.       

John
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SteveG

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Re: '28 Rear Main Seal
« Reply #2 on: May 27, 2014, 06:18:05 AM »
Thank you for your reply.

Your last sentence ("Most all these old cars leak.") really got my attention. I think I'll hold off. It doesn't leak all that much to tear in to it.

I am losing oil somewhere and it just might be burning it, but it is not smoking at all. Does an oil burning car always smoke?

One other thing. If I let it go down more then a quart the oil pressure starts going down. I run about 30lbs at start up and then a steady 20- 22 lbs.

What do you think about all this?

Thank you,
SteveG   


PatrickSmith

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Re: '28 Rear Main Seal
« Reply #3 on: May 27, 2014, 06:04:54 PM »
Steve,

I just completed the rear seal repair on my 31 Plymouth which may be similar to your car. I can tell you I did pull the trans, bell housing, and all other components including the interior floor boards. On my car the flywheel is connected with bolts through the end of the crank shaft and nuts between the flange and block. I personal do not feel removing the pan will give you enough access to the rear seal. I did have a machine shop drill my flywheel then tapped the flange. Now I bolt through the flywheel into the flange as opposed to a bolt and nut.In the future I drop the pan and remove the bolts in one step. I did find a few things on removal of the bell and flywheel: The bushing on the clutch fork had out allowing slop in the clutch arm. I machined in a new bushing and the clutch arm is tight now. The rear seal drops out below with two bolts. Mine was never sealed on the vertical. My engine rebuild kit included two cork vertical  gaskets which I reinstalled with gasket maker. I found a new rear seal by measuring the shaft and cross referencing at Summit Racing. I did not install the rope type rather a neoprene seal. Works perfect.
One thing I did not do during all this work was the front and rear transmission seals. This would have been easy with the trans on my bench. Once I started the car the rear seal on the trans did leak. I was able to access and repair from the rear of the trans without removal. I would recommend replacing the seals when the trans is out. Mine does run around the same oil pressure as yours. Good luck with yours!   

SteveG

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Re: '28 Rear Main Seal
« Reply #4 on: May 29, 2014, 10:16:42 PM »
Thanx for the info. Very helpful.

When I do this job, it is good to good to hear neoprene seals are available.

Also interesting to note that your oil pressure is similar to mine.

My car is losing oil, about a quart per 150 miles. I'm assuming it is burning oil because of wear. Strangely it does not smoke and runs strong.

I'm not going to worry abut it, just curious.

Does yours lose or burn oil?

Thanx for your comments.

SteveG

PatrickSmith

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Re: '28 Rear Main Seal
« Reply #5 on: May 29, 2014, 10:53:04 PM »
No oil loss but I have completely rebuilt the motor. Some very minor oil spots around the oil pan. Prior to replacing the rear seal it did leak enough to create a spot on the floor. All good now. Take care and good luck!

chetbrz

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Re: '28 Rear Main Seal
« Reply #6 on: May 30, 2014, 01:58:21 AM »
Thanx for the info. Very helpful.

When I do this job, it is good to good to hear neoprene seals are available.

Also interesting to note that your oil pressure is similar to mine.

My car is losing oil, about a quart per 150 miles. I'm assuming it is burning oil because of wear. Strangely it does not smoke and runs strong.

I'm not going to worry abut it, just curious.

Does yours lose or burn oil?

Thanx for your comments.

SteveG

Hi Steve,

My old car uses about the same.  I think it burns as much as it leaks.  But like you I don't blow a lot of smoke and I don't drive that many miles anyway.  One of these days I hope to get around to doing some major wrenching on this car.  For now more projects then time.

Chet...
http://www.1948Plymouth.info           Web Master - Forum Administrator - AACA member

SteveG

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Re: '28 Rear Main Seal
« Reply #7 on: June 02, 2014, 03:27:58 AM »
Chet, I am in the same boat. I'll just fiddle with it and drive it like it is.
It is as much fun, if not more, as any car as owned.
Thanx for all your help.
SteveG