Page 1 of 1

Rear Main Seal

Posted: June 28th, 2017, 5:38 am
by wv model AA
I have a friend who working on a Model A Car before getting ready to sell it.

He noticed when the car is running, its loosing oil. What are the reasons why the rear main seal leaks bad when running? Drips a little bit when the engine is turned off.


Thanks for listening.

Re: Rear Main Seal

Posted: June 28th, 2017, 6:07 am
by 1crosscut
Several things could be contributing to it.

Oil level too high. Put it halfway between full and low on the dip stick.
Too much clearance in the rear main bearing or bearings shot.
Drain tube on rear main plugged or missing.
Oil filler cap plugged or pushed down too far creating back pressure inside the engine.
Worn rings and the blow by pushing oil out.
Gasket between flywheel housing and block missing or gone bad.

Others will probably chime in with other ideas.

Is this something that has just started or has it been going on for a while.

Re: Rear Main Seal

Posted: June 28th, 2017, 6:36 am
by Stakebed
isnt there also a slinger ring? or is that only on the front....

if its all of a sudden the return tube has a possibility to fall off - most people make a quick tack weld to hold it in place.

Re: Rear Main Seal

Posted: June 28th, 2017, 6:43 am
by wv model AA
Basically, my friend is trying to help an elder to sell an Model A and they discovered it has been leaking oil.

It appears likely with the severity, I recommended of pulling the oil pan off and starting investigating from there before deciding of pulling the engine out.

Re: Rear Main Seal

Posted: June 28th, 2017, 9:37 am
by 1crosscut
Good plan. That way the seller and the buyer can make an informed decision.