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To replace or not to replace rear main seal 1956

Started by Twan-Sloot, November 15, 2018, 01:20:58 PM

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Twan-Sloot

So my car had multiple problems and it only drove about 500 miles since I got the car 3 years ago. It would always leave a few drops of oil even when just sat for 1 hour or so a few drops would be on the ground leaking from the bell housing. It wasn’t transmission fluid. So i figurered must be the rear main seal. At the moment I have the oil pan off and the car is on the lift so I get a good view of things. The crankshaft behind the rear main seal looks quite dry now actually so I am starting to doubt. Is it the rear main seal or was it the oil pan leaking on the top where it meets the rear main bearing cap. So replace it now the pan is off anyway or leave it alone?

Jay Friedman

Now that the car is on a lift and the pan is off, my suggestion is that you replace both, since a good deal of the work has already been done.  I would not replace the rear main seal with an original rope seal, but with a modern neoprene seal that is sold by Terrilll Machine Company, DeLeon, Texas.  This can be done with the motor in the car.  If you want some pointers, email me at jaysfriedman@yahoo.com and I'll send you an article on doing the job. 

In addition, I would make sure it's not transmission fluid.
1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
Decatur, Georgia
CLC # 3210, since 1984
"If it won't work, get a bigger hammer."

Jeff Rosansky CLC #28373

If it only left "A Few" drops consider yourself lucky.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Twan-Sloot

Okay I guess I should just replace it haha. I ordered the new type rubber rear main seal from best gasket and will install it. I already found a great written procedure on mid century cadillac forum is that the one you are reffering to as well Jay?

Thanks

Jay Friedman

Twan Sloot,

There are several written procedures on the mid century forum on how to replace a rear main seal.  The one I'm referring to was written by Art Gardner.  He and I have replaced this seal on 3 different cars, a '51 and 2 different '49s.  Let me know if you want a copy as it goes into a lot of detail.
1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
Decatur, Georgia
CLC # 3210, since 1984
"If it won't work, get a bigger hammer."

jaxops

Definitely replace it, especially if it already almost all apart.  Those cars are leakers.....took me a few years to replace all of the seals and gaskets ending with the transmission tail shaft seal.  After that, and running the car weekly, I haven't had any issues.
1970 Buick Electra Convertible
1956 Cadillac Series 75 Limousine
1949 Cadillac Series 75 Imperial Limousine
1979 Lincoln Continental
AACA, Cadillac-LaSalle Club #24591, ASWOA

RobertM

My rear main seal leaked really badly after I had my '54's motor rebuilt.  Went back to a rope seal instead of a modern neoprene one, problem solved.

Here's the link to the previously mentioned how-to on replacing that seal through the oil pan.  http://midcenturycadillacs.com/index.php?topic=23.0
Bob Melms

1954 60 Special
1995 Sedan Deville
1999 Eldorado (RIP 2018)
Connecticut, USA

55 cadi

I thought I had a rear main seal leak a couple years ago, turned out to be the oil pressure sensor, it leaked down past the rear main seal so it looked like that was the problem, luckily it wasn't, far cheaper and easier fix.
1955 Cadillac sedan series 62
1966 mustang convertible w/pony PAC, now in Sweden
2005 Cadillac deville

Twan-Sloot

finally found the time to complete the job after my oil pan painting disasters haha.

Out with the old in with the new.

The old rope seal came out very easily. The rubber seal was relatively easy to push in as well.

Let’s hope all is well now :)