I just bought a 30 Model A, it runs good and drives without any problems except for a bad oil leak from the back of the engine. I've replaced rear main seals of all types, rope, two piece, one piece, but never seen the inside of one of these. I've read that there is no main seal, just an oil slinger and drain tube. Also that there is a rope seal in there. Also that excessive bearing clearance might be part of the problem. I've been told that in order to fix this it would be just as easy to pull the engine. I have a lift and don't see why it couldn't be dealt with from underneath. Who knows these things, what would you do?
Welcome to banger land.... Stock A engine rear main is configured basically as you stated, with a slinger and drain tube, there is no rope seal. The rope seal is on the front pulley and the pan. Yes, the rear main can be serviced from under the car and bearing clearance checked as well. Model A's like to mark their territory....so, after stopping an oil spot from a quarter to a silver dollar size is to be expected.... The oil pan has a no lip at the rear of the pan, just the edge wall of the pan that seals against the cork that is between it and the main cap....oil can leak there too. For the rear main to drain properly, the drain tube and oil drain p***ages in the cap must be open (no babbett blocking it) and the end of the tube must be below the level of the oil in the pan. There are two lengths of drain tubes, one for the A engine and another shorter one for the B....the B engine has a larger bearing journal, so shorter tube. If someone installed a B tube on an A main cap the oil level might be too low for the tube. If the tube end isn't under the oil level, the crankcase pressure will blow up the tube and out the rear main carrying the oil draining off the bearing to be carried out the back of the journal with the crankcase pressure. Soooo.... first step I would take is to check for excessive crankcase pressure. It can also cause oil to be pushed up the tube and out the rear main.Make sure your cap on the oil fill tube is venting and maybe even check for excessive pressure with the cap off. Second....'overfill' the oil pan by a quart to make sure the drain tube end is immersed. Then take a drive....see results and look the underneath over real good, If if is still dripping excessively out the flywheel housing, it is the time to think about pulling the pan.... There are many nuances to completing the inspection, adjustment and reinstallation of the rear main cap and pan successfully and be warned, you may find that the reason for the leak is broken babbett bearing material in the main cap....also, this would be the time to check all main and rod bearing condition and clearances... Hope I stated this in an understandable manner Good luck Larry
Look up strong’s garage on yt they have a pretty good video of the issue I think, myself I would be inclined to drive it for a while if it’s running well and the oil leak is not outrageous, its possibly stuck rings creating too much crank case pressure . Opening it up could lead to a total rebuild Don’t use high detergent oil either, that led me down the path to a rebuild of a running engine
I park my flathead powered sedan over a 4x8 sheet of plywood. Soaks up the spilled dinosaur juice from the engine, transmission, torquetube, and rearend all at once.
My A engine was done by Antique Engine Rebuilding. Leaks a couple drops a week. Best advise I can give a new A owner is buy and oil that will look good on your driveway.
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