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

I am getting ready to change the rear main "rope" seal in my '53 truck 216. It dumps a lot of oil, and has to be done. I have read other posts about a small check ball back there? I am not familiar with that, and don't know if I have one to deal with or not. I think that is pre-1940, and my engine is the same as the passenger car 216, 1940 through 1952 (also last year 1953 in light trucks, only).

Any thoughts or helpful experience to share?

I am not pulling the engine, everything else is fine. I don't want to have to drop the crank, is it possible to just loosen things up and get the upper half of the seal in, or do I need to be happy just getting the bottom half in? Or is it not worth bothering with unless you do both halves?

There is no check ball in your engine.

To replace the rope seal it will be necessary to loosen all the main bearings so the crank can fall a short distance. There is a special tool that is used to pull the top seal over the crank. Should be available at your local parts house.

The key to this replacement is to get a perfect match from the top to bottom seal. Tighten the main bearings and then shave the ends of the top seal. Use a hammer handle or suitable tool to 'roll' the bottom seal in the bottom 1/2 bearing cap. Try to 'cram' the seal in rather than 'stretching' it.

Use a bit of sealer at the ends of the new seal.

(Keep your head from being directly under the crank. That drop of oil in the eye is no fun).

Thanks very much, Ray.

Would you care to describe what that special tool looks like, or what it does exactly? My buddy at NAPA had no idea what I was talking about.

Sounds like maybe you have experienced that drop of oil?

Couldn't find my tool immediately, but it is a strong cable with a "T" on one end used to pull it and a corkscrew on the other. Feed the screw end over the top, screw into the "wick" end, lubricate the seal with axle grease so it will slide easily, use the "T" handle to pull the seal up and over.

If it hasn't dropped any oil for 1/2 hour, as soon as I go under and look up, you got it, a drop of oil in the eye.

years ago I used a main bearing seal puller made with a "T" handle on what looked to be a short piece of small aircraft control cable with a small woven end of the cable that works like a Chinese finger trap. It had a cool name but I can't remember what it was, C.R.S. has set in again.

Ray is dead on about not streaching the rope seal and getting the rope to fill the space and then cutting the ends of the seal, even with the engine out of the car and on an engine stand. I have never used a neoprene or rubber type of seal in the older (54 back) engines.

My experience with this type seal, pull the top piece through until it is approximately half way through then force as much of the ends in as possible before trimming as close to flush as possible.
When setting the lower piece, thin it as much as possible while keeping the curve. When you sit it in the groove use a hammer handle to spread it into the groove working from the ends towards the middle. Then trim the ends so that they are slightly higher against the crank and shorter at the bearing cap groove edge.
By trimming the lower section as above you apply extra pressure on the seal face.
Tony

Thannks, Gents, for all this information!

I will let you know how it goes. I am waiting on the oil pan gasket from the Filling Station.

Well, I have learned some more. The Special Tool you all are talking about is called a "Sneaky Pete." I finally found one. Actually, it is two tools - the corkscrew looking thing that pulls out the old seal, and a wire with a clip on the end and a T handle, that pulls the new one through.

I didn't get to the job this past weekend, got tied up with some body work that took longer than planned (it always does, should've known).

So hopefully I will get on this late this week.

Yeah, that is it a "Sneaky Pete", named after that famous prohibition wine beverage that also gave the drinker a bad case of "Jake leg"

OK, the Pan is off, the Rear Main Cap is off. All main bearing caps are loosened. The spark plugs are out.

The Crank Shaft will not drop down, to give me any play. Have tugged and pried. Any ideas?

I am also wondering if this was a waste of time. The old seal in the bottom was not broken nor did it look too bad at all. Hard to imagine it was letting that much oil out the back. But at least it will be eliminated as a possibility.

You may not see that the crank has fallen down, however, with the action you have taken, there will now be a better chance of getting some compression on the top 1/2 of the seal when you retighten the mains.

Too late now, but in the future, and a leak is detected, it is best to clean everything up and make an attempt to see exactly where the leak is located. Many rear seals have been replaced to fix an oil leak from the back of the engine at the valve cover. Amazing how many cork gaskets have managed to slip out from under the valve cover at the back.

Another favorite place to produce a leak is at the lower left of the push rod cover. A difficult place to get to and insure it is assembled correctly.

When the dust cover has been removed from the flywheel, a close inspection of the front of the flywheel will give an indication of a rear seal leak.

As you say, the chance of the leak being at the rear main has been reduced.

Thank you, Ray. This has kinda stopped being as much fun as it was. Slow going, I am getting about 1/4" inch of the upper seal at a time, and only have maybe about half of it out. The corkscrew tool has pretty much stopped biting in. I need a mminiature roto-rooter, I think!

I suspect getting the new seal in is going to be a real challenge, too...

Two things you can do that might help. Loosen the fan belt so the front end is not supported and engage the clutch so the back end can fall down further. Clutch does not need to be held in, just push it in and let it back out.

You may find it helpful if you rotate the crank in the proper direction as you remove the old and install the new.

To help controll the leakage at the rear main I would suggest following the instructions in the Oldsmobile shop Manual (307 engine) in the 1980's.That engine still used a rope seal.This was in the G&D several years back.I believe Bob
Adler wrote the article.
The instructions in the manual are-
remove the bearing cap.Use a seal packing tool and pack it ends of the upper seal up into the grove.This will make the seal fit tighter to the carnkshaft).Remove the lower seal and cut of the ends,packing the cut-off ends into the space made by packing the old upper seal.The packing tool looks like a blunt ended punch just a bit smaller than the diameter of the seal grove......Install a new seal in the cap and go from there.Its advisable to remove as many shims as possible to reduce the oil flow past the bearing....set clearence to about .001" - or so the crank will easily rotate (with out the drag of the new seal).
Another method that was used years ago was to drive a piece of wire up into the upper seal, causing it to expand and fit tighter.
The modern replacement seals are of much poorer quality than the old rope seals sold by Chevrolet years ago.I found some NOS genuine chevrolet seals on Ebay a few years ago...now all I need to do is find the time and energy to install them in my '50.

Hi, Gene, thank you. I might well have tried that approach, but it is too late since I already have most of the upper half of the seal out now, in pieces.

Ray, I did check for any other possible leak locations before going in to the rear seal. The rocker cover is dry in the back. Although the push rod cover is a little juicy, there is not enough oil flow there to account for the quantity of oil I saw on the ground whenever the truck was run. Plus, it runs out of the lower flywheel cover hole. Don't see anywhere else for oil to get in there. I will try the clutch and loosen fan belt ideas to gain a little more slack.

Thanks, guys. The mission continues.

Years ago I had a lot of trouble removing the rear seal while the engine was in the car. I used Sneaky Petes, modified corkscrews and various other 'special tools' all to no avail except frustration. What finally worked was a plain old coat hanger with about a 1/2 inch hook on the end. I bent the 1/2 in. completely over and sharpened the bent end slightly and then drove it over the top of the seal. Once I had the hooked end completely through I bent the hook out slightly. I then put a slight pull on the hanger and turned the crankshaft in the same direction of the pull and the seal came out easily. As if anything can be done easily in that location!! If you have any questions give me a call. (318) 798-0493.

Caution if you PULL a new seal into place.Pulling the seal will cause it to srtetch and leak oil.After the seal is pulled thru it should be packed back into the grove.

I am very happy to report that the old rascal is out of there! And it WAS a rascal.

Tomorow, time permitting, I will clean up the mess and start the joy of getting the new one pulled through. And I will take all of the advice posted here - and I appreciate it all.

Eventually, this old truck will be running around without leaving so much of its oil behind. Thanks.

GOOD LUCK................

Well, I had to vanish for a while, I was gone for 4 days to Florida. My Dad had some sudden health issues and I wanted to go there, but all is well, and I am back.

Today, I finally got back to the truck. Pulled through the new upper seal, wrestled with the oil pan gaskets, and got things buttoned up. Oil pan was a lot of fun laying on my back. I almost cussed, once...

I am happy and a little proud to say, it does not leak.

Now there is the matter of what looks like the timing cover leaking. Didn't notice that one before.

Timing cover or front balancer seal - or the front cork seal on the pan?.
Seal can be replaced by just pulling the balancer...thats the good part.

You know Gene, it looks like it just might be that cork gasket, in the front curve. It's really hard to see where the oil comes from, but by bending my neck and body at extreme unnatural angles, I think I am seeing a leak there. It's worth a try to re-seat the oil pan, before tearing into the front of the engine. It went in weird, it kind of wanted to rock until I pulled it down with the screws. I couldn't determine why it wouldn't go up nice and square, but it did pull down with the screws.

Understand, this is not a restored truck, it is a true "survivor" that I am using as a truck. So things are kind of old and nasty (although steadily getting better) and therefore hard to see things.

I would suggest re-tightening the pan bolts after a few days.The modern cork composition gaskets are much harder than the old plain cork and it takes more force for the pan to make a good indentation in them.Also doing it when the engine is hot may help.The hard cork for the ends is what makes it so difficult to get the pan up in place.I use a little jack and 2x4 under the pan to push it up and hold in in place while starting the bolts/screws.Just don't get too carried away and break off the end bolts...rather retighten again in a week or so.
Did you put the side gaskets in place first before installing the end corks?If not you will get a leak in the corners and it will run down to the center.

Hi, Gene and everyone - welcome back to Bowtie Cyberspace!

Just to complete this particular story (I know you're all holding your breath), it was the front cork leaking. When I pulled the pan back off, I found about 1" of the end of the front cork had doubled backward and was definitely letting oil out. Hard to imagine how that could happen, as much care and double-checking as I did - not to mention it was pretty well glued down with silicon before it went on. Anyway, it is re-sealed now, and not a drop anywhere. Feels good.