Rear main seal replacement on 1956

[Stevison]

Hey folks, my 56 coupe Deville has a leaking rear main seal. The mechanic is telling me but because of the cross X frame, the only way to replace the seal is to pull the engine, as opposed to simply dropping the transmission. This sounds weird to me, but I thought I would check with those who are brighter and better informed. Thanks!

[J. Gomez]

Henry,

Yes, it would be easier to do the job with the engine out "BUT", there is no need to pull the engine out just to replace the rear main seal even if you go with the old rope style seal. One will need to be very-very careful but it can be done.

You will need to pull the oil pan and loosen the steering link to remove the oil pan, remove the oil pump to gain access to the rear main bearing. If you have the Service Manual you will notice the location for the seal.

I would suggest in installing the new neoprene style main seal versus the old rope style to make the job easier.

Good luck..!

[Cape Cod Fleetwood]

How much oil are you losing... It might be cheaper/easier to put a throw away aluminum cookie pan under the car and check your oil level regularly.

[Caddy Wizard]

In a good many situations, what looks like a rear main seal leak is leaky valve covers.  The oil runs down the block and drips off the back of the oil pan, simulating a rear main seal leak.  Replace the valve cover gaskets first.


The motor does NOT need to be removed to replace the rear main seal.  It takes about a day with the engine in the car, including cleaning things and maybe repainting the oil pan.  There are posts on this Forum about how to do it.  Also, lately some of us have been having trouble getting the new neoprene seal to seal properly.  Some have speculated it is because the seal is precision made, but the channel in the block is not.  To address this, some of us have been "shimming" the outside of the seal to make it fit a little more tightly against the crankshaft journal.  I had to do this recently when a new rear main seal leaked after installation.  I used some thin gasket material and it did the trick. There is a thread about this aspect of the job on this Forum too...

[Jay Friedman]

Art, the Caddy Wizard, and I wrote an article with step by step instructions for replacing a rear main seal without removing the motor.  Send an email to jaysfriedman(at)yahoo.com and I'll reply with the article attached.