Oil leak at rear of engine on 47 Plymouth P15.....what is the most likely culprit? Is a 1957 model 230, flathead 6.

[BobT-47P15]

Has started leaking some oil at rear of engine.  Have not crawled under to look yet.  Thought I would ask better mechanics than me for possibilities.  The car has been sitting a lot in last few years.  Thanks for any info.  Bob in Joplin, MO.

[Curt Lee]

Is it a constant leak that drips relatively fast or does it take a while to accumulate? More than likely the rear main seal but that is an undertaking to replace. Sitting doesn't do these cars any good at all.

[Ivan_B]

You need to take a look... Most likely source of leak at the rear of the engine is the crank seal. But it could also be leaking from elsewhere, and flowing down the metal shields toward the back. Could be a transmission leak as well.

[Sam Buchanan]

Another possibility is the oil pan. The rear of the pan where it transitions over the bearing cap can be difficult to seal and create a significant leak. 

[kencombs]

If it's the seal, that year should have a two piece neoprene seal.   MUCH easier to replace than the older versions.

[andyd]

Also on each side of the rear main cap are small seals that will be one of 2 shapes........make sure the correct shape ones are used or that they ARE actually there.......also the oil pan side rail bolts are easily overtightened resulting in a squash cork gasket that will leak..........I'd order a new pan gasket /seal set, also rear main gasket and have at it.........andyd

[rallyace]

One more place to look is at the oil pressure relief valve on the left side of the block below the distributor. The oil filter lines connect to the block here. If they leak, the oil will run down the edge of the block and drip out at the rear of the engine. I was ready to pull my transmission and replace the rear seal when I spotted this was the location for my oil leak. If this is where it is leaking it is not that difficult to fix.

[greg g]

My oil filter return line split inside the fitting.  New piece of tubing fixed it.  Also check the flex line feeding the oil pressure gauge.  There is one more source but it's behind the bellhousing.  The Welch plug where the rear cam bearing sits, but it pretty rare for that to leak.  If most of your oil is drivers side, I would suspect filter or gauge plumbing, or where the distributor  sits in the block.  A trip to the car wash to clean things up may help you locate the source.

 

 

Good to hear from you.  Been a while.

Edited August 27, 2023 by greg g

[BobT-47P15]

Thanks for your thoughts on this leak, gentlemen.  As Greg said, i havent done much posting the last few years.  The car has sat a lot.  I start it and let it idle until warm every so often.  It’s more difficult to find mechanics familiar with older cars as many are not able to do the work due to old age, etc.  Will try to clean up the floor and inspect things to see if I. can locate the problem.