Re: IML: Rear Main Oil Seal on a 1966 Imperial

[sosmi@xxxxxxxxxxx]

There are a few things that might help seal the rear seal leak. The original seal was a "rope type", changing these can be a chore at best. Many times the crank shaft seal surface can be damaged by the removal, and replacement of the old seal, which results in another leak. The seal bridge can also contribute to the leak as well. The wrong choice of gasket sealers can also be a problem. The crankshaft seal surface (diagonal cuts) are designed to pump the oil back in the engine, with just enough to lube the seal and keep it from burning out. There is a two piece lip seal to use rather than the the rope, but if the surface was damaged, it could leak as well. There also is a #5 bearing designed for high mileage engines, it has diagonal cuts to shed more oil forward, rather than back at the seal. The seal bridge is the next problem, the side seals need to be activated (so they swell-up and seal) I give a quick dip in a 50-50 mix of engine oil and mineral spirits. This promote s the swelling operation quicker, but don't wait too long to install them. I use Permatex #2 sealer (the factory choice) on the base of the seal bridge, it will seal even if there is any small amounts of oil left on the block surface, silicones (RTV) will not bond to any oily surfaces. Last is the oil pan gasket, I check the pan gasket surface for a flat mounting surface. Laying it face down on a flat surface to check it, any high spots should be trued-up so it compresses the gasket correctly. Then glue the gasket to the pan, I prefer a contact cement, giving it a long cure time, for a sure bond. The block surface should be washed with brake cleaner, then apply more glue to the gasket, a small dab of #2 to the seal bridge corners, and timing cover joints and install the pan before any oil drains down on gasket surfaces. Torque bolts to just snug, and give the glue a chance to cure, then do the final torque. The best gasket to use is a compressed paper type (Victor) the co rk or rubberized type tends to "squirt" out, and doesn't compress as well as paper types. A 24 hr sit is best before starting. There ya go. Dave.

 

-------------- Original message --------------
From: tcufroggie86c@xxxxxxxxxxxx
All,
I apologize for the wide distribution. I have perused the archives on the OIC site, and on the internet, but have not found the information I am seeking.  I have a 66 Imperial Crown Convertible that has a nice leak at the rear
main seal.  My mechanic has replaced the seal once, but the problem reappeared shortly (4-5 days) after
the seal was replaced.  I have seen on the OIC website that it mentions a worn crankshaft can
contribute to the leak at the rear main seal.  My mechanic has stated this as a possiblity also and has shown
me where there is some wear in this area on the grooves of the crankshaft.  Neither he nor I are particularly enthusiastic about replacing a crankshaft, thus it is not my intent to replace it. I ca n live with the leak
instead of performing such an intrusive procedure. 

My question(s) are as follows:

1.  Was the original rear main seal a rope type seal or a smooth type of seal for the 66 Imperial?

2.  Is there a "double" or oversized rear main seal available for Imperials?  I recall that big block GM cars
had  these oversized type seals to fix this annoying leak.

3.  Any other suggestions on how to fix this issue on the 440 engine in a '66 Imperial?

Please feel free to reply to me directly at tcufroggie86c@xxxxxxxxxxxxx   Thanks in advance for your help.

Sincerely,
CCC

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