VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc 1941 Rear Main Leak

My grey 41 has started pouriing oil faster then the Morton's girl loses salt. You get the picture.

I dread the job of installing a new seal. Engine runs just fine and does not need overhaul. Just gasket(s).

On youtube I discovered the below video of a cure (?) for this problem. I wonder if anyone has tried this and how well it works.

Please let me know what you think also,

Best,

Charlie

That looks like way more work than I would want to put in. Plus, I don't have an engine stand or any of the machining tools.

I have the same problem, just not as bad as you describe. After replacing the oil pan gaskets, I discovered most of the leaking is coming from the rear oil seal. But, it only seems to leak after driving it. If I have to pull the oil pan off again to replace the rear seal, I think I'll just wait and let it drip until the next oil change.

How difficult is it to replace the rear seal? Going by the shop manual, which doesn't give you a full step-by-step, I was assuming you just might have to remove the oil pan and then the lower half of the cap and replace the rope-type seal.

David Miner did that to his 1940 and said it worked well.
You will need to remove the emgine and remove the crank shaft , a major operation that could cost big money.

Dave also did it to his cousin Dale's '48 featured on the cover of this months G&D. He also put an article in the G&D about it some months back, I believe.

I have replace the rear main on both my 1951 216 and on the 1940 216 in my 38 Master. Both I replaced while the motor was in the vehicle, and they were successful. I have subsequently replaced them when I overhauled the motors out of the vehicles.

I used the new "Best Gasket" seal. I adjusted the main bearings to their minimums. I removed the transmission, backed off the main caps some, more so towards the rear and used picture hanging wire to pull them in. I lubricated them with the thick Lucas oil additive. I was careful not to slip a timing gear tooth.

For anyone who can do the machine work, the one-piece rear main seal is what should have been done to begin with and a great answer. It certainly isn't that those seals didn't exist back then. They just cost more than a piece of rope. Here is an unorthodox alternative to the misery of replacing the rope seal with the engine in the vehicle...and it won't cost you much to try this.

I knew a mechanic who did this frequently back when I was in high school and I learned the technique from watching him. Later I tried it on a 1956 Cadillac engine and it did help the rear main seal problem notably. However I learned after doing it that engine is notorious for leaking at the galley plug and it will always run down the back side of the block and mimic a rear seal leak.

Anyhow, here is the method:
1. find an old style windshield wiper blade and remove the long, stiff and thin stainless steel strips. There will be 2 of them. If you're lucky they'll be the right width for the channel into which your rear main seal fits. They're polished smooth and this is what you'll need.
2. using the rear main lower bearing cap, cut the length of the strip so it fits exactly end to end in the bottom of the channel. This isn't difficult. The strip is going to want to be straight anyway, so it will hug that channel. Grind one end tapered (like a knife blade) and then carefully file the corners of it so they radius a wee bit.
3. using a small hammer, tap that strip underneath the bottom of the rear main seal you have in there right now. Don't try to remove the rope seal. What you're doing (obviously) is pushing the rope seal closer to the crank journal by the thickness of the stainless steel strip (which is probably going to be about 20 thousands thick) by forcing the strip between the channel and the existing rope seal.. This is often all you need...usually wear in your main bearing is the problem to begin with. Tap slowly and position the strip so that the part you ground like a knife blade faces the rope...so the strip will not want to dig into the rope as you tap it through. You probably will have to loosen all the caps a bit to do this. Loosen the front ones less.
4. when you've driven the stainless strip all the way through, stop and re-seal the bottom cap normally. That cap isn't a problem to re-seal in the first place. Leave about .004 or .005" of the bottom cap rope seal sticking out. Don't trim it flush like the shop manual says to do.
5. re-install the bottom cap, the oil pan, the oil and say a prayer.

Good luck!
Jon

I mentioned to tap the strip slowly. I should have added carefully. Please don't just start whacking at it. You really don't want to disturb the existing upper seal...if you can do this right, you'll just force it outward gently and then push the crank journal back onto it when you torque the cap again. Point being please take your time. Oh, one other thing...you'll notice the upper rope seal will probably stand proud at the ends by .008 to .010 now. That isn't a problem. Again good luck!
Jon