main oil seal

[Cooke]

I have posted in the tech forum but no replies, I am sure someone here has done this. I have the main oils seal gasket and the directions indicate that it can be done without removing the crank, has anyone done this? Its on a 1938 V8, it only leaks a a few drops a day but I might repair it this winter.

Thanks, Martin

[D.Yaros]

I know absolutely nothing about the '38 model year.  Having said that, on 40's, 50's & 60's era cars the main seal is indeed replaceable without dropping the crank.  One removes the oil pan, and with a wire rope toolextracts the upper seal installs the new.

[harry s]

Martin, As Dave mentioned the seal can be replaced without removing the crank. I've never done a replacement in the car but after removing the oil pan you would have to remove the rear main cap and also loosen the front and center cap to allow the crank to drop slightly. I'm pretty sure you would also have to remove the tranmission cross member to allow the trans to drop . You would have to support the trans after the crossmember is removed. There is a replacement seal for mid 80s Mercedes Benz diesel the works with the Cad flatheads much better than the rope seal. I don't have the part # handy but am sure others will have it. The part number and installation process has been discussed on the forum before so it is probably available through a search. Good Luck,    Harry

[Gene Beaird]

It's nice that there's a rubber seal available.  That might preclude loosening all the mains to get the crank to drop a bit.  Getting the old one out will be the hardest part, but a rubber seal should go in w/o dropping the crank down any. 

I'm not at all familiar with this particular instance, but with the 472 seal, some fitting is required for a nice tight seal.  You'll want to verify if fitting (usually just grinding a bit of the reinforcement wire down with a bench grinder) is required or not before bolting everything back together.  It's a small, yet very important detail to mention.

[harry s]

The Mercedes seal comes in a single length which has to be cut in two and fitted to the block and main cap. It should be fitted and then trimmed just a fraction of an inch higher than the part so as to allow a tight fit at the seam. I like to use a sealent on the back side and assembly lube on the contact side. Like I said before I have never done this in the car so I can't speak to difficulties in removing the old or fitting the new in that situation. If you go this route keep us posted.
Harry

[gary griffin]

I replaced such a seal on a 1961 Chevrolet but I think the procedure is the same. Loosen the bolts on all of the crankshaft bearings and you should get a very small gap at the seal. Remove the cap on the main bearing.  For a few dollars I think you can still buy a tool that was called a"Sneaky Pete". There are two components to this tool one is a sort of corkscrew with a T handle that you screw into the end of the seal and pull the old seal out.   After you get the old seal out the other component is a small wire with a T handle on one end and a clamp on the other end.  You feed the clamp through the cavity that the seal occupies until clamp comes out the other side and affix the clamp to the end of the new seal and gently pull the new seal through the cavity. Push on the other end of the seal at the same time and by the way use plenty if light oil for this process. I used a seal that was intentionally too long and after the seal is through the cavity carefully trim the ends to fit tightly around the shaft. The joint in the seal should be as high as you can make it about where the end was sticking out of the cavity.  A one piece seal is preferable to me because it only has one place to leaf.  Then tighten the bearing caps to specifications and put he pan on and drive worry free for thousands of miles.   If you were near Seattle I would loan you  my sneaky Pete (which has not been used since 1968 but I cant get myself to throw it away)  but they are only a few dollars. This is far easier than it sounds and only takes a few minutes. I hope it works on your Cadillac!!