1920's Buick Rear Main Engine Seal

[Hubert_25-25]

The rear main engine seal on my 1925 Buick was cork and it had a wire behind it.  The car has not run since the 60's so I have no clue as to how well these seals work or held up over time.  Is cork what people would suggest should be used as a seal when I put my motor back together?  I know that they used this design for multiple years, but that was many years ago.  I am also missing one of these 2 wires.  Does anyone have an extra wire if I end up going back with this style of seal? 

Thank you,   Hugh

 

Edited February 15, 2018 by Hubert_25-25 (see edit history)

[carmover]

Hugh Mine didn't have any wire behind it.I ordered a new one from olson's Gaskets and the machine shop installed it with out any problems.I haven't started it yet so I don't know if it will hold up or not.     Ron

[Hubert_25-25]

Ron, 

     The wire shows in the parts book.  I think the intention is that the seal spins on the shaft and not in the bearing housing.  You have more surface area in the housing than against the shaft, so that helps.  I think this would just be an additional extra measure.  I also noticed one company selling a rope seal kit, and they included a small roll pin to install in the bearing cap so that the seal does not rotate.  Since your car is all buttoned up, I would not worry about it.   Hugh

[Hubert_25-25]

Since no new manufacturers use cork for their rear main seals anymore, I was wanting to try something more modern.  Here are the specs.

Crank OD .2415

Bearing cap ID 2.815

The seal groove is .20 wide at the bottom and .25 wide at the top.

The Cork material originally used is 1/4" x 1/4" in cross section.

    It appears that the same seal is used for all Buick 6 cylinders from 1925 to 1930.

I talked to Best Gasket and they recommended their smallest rope seal which is .210 thick x 5/16 wide in cross section.  Best rear main kit #6340

Best had no experience, just picking this out of their catalog getting closest to my dimensions, and no seal specific listings prior to 1934.  I talked to Egge, and they said that they carry the seal as it is used in later model Buicks but could not tell me if they had tried it in a 20's Buick. 

     I was wondering if anyone had used rope packing in their rear main seal on these Buick engines.     

Thank you,   Hugh

     

 

Edited October 19, 2018 by Hubert_25-25 (see edit history)

[Hubert_25-25]

More details than you want to know about rear main seals.  There are two wire retainers used with the original 1/4" x 1/4" cross section cork rear main seals.  The purpose of the wire is to prevent the cork seal from rotating in the bearing cap and block.  The .035 wire is stiff and you could make new ones if you needed to easily, just use a wire that is a little difficult to bend.  A lot of the wire available is very pliable.  This is almost like spring or coat hanger wire.  Notice that there is also a tiny hole in the bearing cap and in the block just near the parting line.  Just the corner of the wire goes into the hole and that is what keeps the cork seal from spinning.  The hole and the curve in the end of the wire is shown in the first photo.  

   As a modern upgrade, I am working on installing the Best Gasket rope seal that I purchased from Egge.  This requires drilling a small 1/16" hole in the end middle of the bearing cap and installing a very small 1/16" diameter roll pin, so I no longer need the wires.  I am still playing with the rope and tapping it into shape.  Oddly I found a socket that is exactly the diameter of the crankshaft, so this helps with the photos and shaping the rope.  I will cut the rope per the instructions and post when I am done.      Hugh   

Edited October 23, 2018 by Hubert_25-25 (see edit history)

[ROD W]

Hugh,   You don,t think using the original spring wire,  would hold the rope in place.

[Hubert_25-25]

Rod, 

      The cross section of the rope is the same as the cross section of the cork, but the cork compresses easier, so I am a little concerned about fitting all of the rope in plus the wire even if it is a small wire.  Another thing is the instructions only call out one roll pin in the cap, so the block side gets no wire or roll pin in case you would need to put a new rope in later it would be much easier.  I assume that is the reasoning.  I am following the directions of the rope kit, but the wire just looks to make it a little on the tight side. 

[Hubert_25-25]

Photo order

1) I drilled a short 1/16" hole and installed the small roll pin in the bearing cap.  I used a punch to make a hole in the rope seal to prevent rotation.  I pushed the rope seal in the cap as far as I could.  I could still see that the sides of the rope seal were squeezed tighter than at the bottom when I tried using the socket to push the rope seal in.   I pushed the rope seal in as tight as it would go with some light tapping with a rubber mallet on the socket. 

(No Photo) From the kit, I used the knife that was provided, and the shim, and the wood piece to cut off the rope .015 proud of the mating surface  

2) I wanted to do a dry run of the seal and make sure it was going to fit, so I used the socket and began slowly pulling the bearing cap down on the rope seal.  The rope seal is oil impregnated.  I did not want to hydraulically overpressure the bearing cap where the seal is.  I wanted to pull it down slowly so that the excess oil could escape.  I took my time cross tightening the 4 nuts in the bearing cap and only using a 3/8 drive hand socket.  I also occasionally rotated and wiggled the socket to be sure that it  still was not binding and overpressuring the oil seal retainer.  I only pulled it down tight to where the mating surfaces touched.  

3) This photo is of the seal area when I pulled out the socket.    

Continued on the next posting

 

 

[Hubert_25-25]

4) This is the bearing cap.  The rope seal has been pre squished so to speak.  There is red assembly lube on the bearing surface and on the rotary surface of the rear main seal.  I used Permatex copper coat gasket in a can.  The can copper coat is very thin.  It comes with a ball applicator, but I used a small paint brush to control the application better.  I wanted the coppercoat on the mating surface, and assembly lube on the bearing surface.  I did not want coppercoat on the bearing surface or the rope seal ends.  Because this is a mating surface that can leak oil thru the surface, I wanted to keep oil from migrating thru to the outside.  The 2 rear main bolts are also outside the oil pan which is unusual.  I wanted to prevent an oil leak down these 2 bolts so there is sealant around the mating surface of the 2 bolts.  The rest of the surface has compound on it just to be evenly spread.  

5) This photo shows the similar set up to use gasket compound on the block side.

6) Installing cotter pins.  Side note - The special flywheel bolts must be installed prior to installing the crankshaft.  

Edited November 1, 2018 by Hubert_25-25 (see edit history)

[Slawnski]

I’m not looking forward to changing main seals on my 27….thank you for walking through this Hugh! 

[Slawnski]

My gasket kit comes with cork- I’m not sure if I’ve got wire in there just yet. 

[Fred Rawling]

I had a rope seal from something in the 1940's or 50's.  It was about 3/8 oval shape.  It fit in the groove and only stuck out a little. I pushed it in ja bit with a screwdriver handle and bolted it together.  Maybe I was lucky to the the right rope packing.