Rear Main Seal on 1928 LaSalle

[Kent Rowald #13148]

My 28 LaSalle 303 is getting about 10 miles to the quart of oil because the rear main is leaking so badly.  Any suggestions on where to get a new rear main seal to put in it?  Thanks.

[Wayne Womble]

I have seen complete reproduction gasket sets available lately. Cant vouch for the quality. I find it hard to believe that it would leak that bad even if the seal was very bad. I think you should check the oil return line at the rear main bearing cap to the oil pan. It might be plugged or the pan gasket may be covering the hole.

[Bill Sullivan]

I am not positive, but I dont believe there is a rear oil seal on this engine.  Just a slinger and a return line to the crankcase.  I dont think the Cadillac V-8 got a rear seal until 1938.

Waynes suggestion is good, but my experience with rear oil leaks is that worn pistons/rings/cylinders and main bearings are usually the culprits.  These problems lead to high crankcase pressure and too much oil flow through the rear main bearing.  This is too much oil for the slinger and return to handle, and the flow of crankcase gases blow the oil out the rear.

If this is what you have, your choices are to rebuild the engine or just keep adding oil....

Good luck!
Bill.

[Paul Ayres #5640]

Kent - There is no oil seal in your engine.  There is an oil slinger, just a disc on the rear of the crankshaft, which slings oil from the rear main bearing into a groove in the crankcase and the rear main bearing cap.  There is a drain hole in the bearing cap which conducts the oil back to the crankcase.  It is probably plugged with sludge.  You should drain the oil, drop the oil pan, support the crankshaft from below, remove the rear main bearing cap, and clean out the hole.  Some leakage from the rear area is not uncommon, and in 1932, Cadillac added another drain path for the oil at the rear of the oil pan to try to cure the problem.  When you replace the main bearing cap, pay close attention to the two square wooden plugs, one on each side of the cap where it fits into the crankcase.  These will also leak oil if not properly installed.  They should be pressed into the bearing cap, then when the cap is in place in the crankcase, drive a pointed piece of 1/16" wire all the way through the wooden plugs to expand them against the crankcase.  This should cure your problem.  Paul Ayres

[Kent Rowald #13148]

Thanks to all of you!  I pulled it down this weekend and found that, as Paul suggested, the drain hole in the bearing cap was completely clogged.  Moreover, the wooden pegs were missing completely!  I was flabbergasted to find the groove and no wooden plugs (I was frustrated at going through the manual tryin to find the rear main seal and kept finding references to the wooden plugs instead, so I just dropped it to see what was there) instead of a rope gasket.  Now that I have confirmation that what I thought was going on is correct, Ill quit puzzling about it and put it back together.

Thanks for the info - while I like to tinker, Ill never be mistaken for a "real mechanic" and dont have the time to become one!