naa rear main question

equinehauler

New User
I am currently replacing the rear main seal on my 54. I dropped the pan, and removed the rear bearing cap. the rope gasket that I purchased from Stevens tractors is to large to fit into the grove. The old one looks like it didn't have any of the coated outer cover against the crank, only in the cap itself. Am I missing something?

47061.jpg
 
(quoted from post at 09:12:49 03/25/17) I am currently replacing the rear main seal on my 54. I dropped the pan, and removed the rear bearing cap. the rope gasket that I purchased from Stevens tractors is to large to fit into the grove. The old one looks like it didn't have any of the coated outer cover against the crank, only in the cap itself. Am I missing something?

None of them will just drop into the groove. Have you tried first flattening it with a big headed mallet?

After you get it well into the groove, then using a tool like a half inch rod or a small wrist pin or something, you forcefully set it deep into the groove, starting your rod pressure from the top edges down to the center of the hollow.

That seating process will of course widen the exposed surface beyond the width of the groove but that's fine.

If you are planning to install the upper half with the crank in place you might have to loosen the mains to lower the crank very slightly.

If you do the block side first you can use your main cap to shape the rope first . . . before you start trying to pull it into position in the block groove.

Removing the old half from the block and how to pull/roll the new one into position by rotating the crank and pulling is another story. :)
 
Thanks for the reply. The picture shows what is left of the seal after tapping it into the grove. There seems to be too much material left out for the cap to bolt in correctly. Is it possible that these seals are the incorrect ones?
 
(quoted from post at 11:25:29 03/25/17) Thanks for the reply. The picture shows what is left of the seal after tapping it into the grove. There seems to be too much material left out for the cap to bolt in correctly. Is it possible that these seals are the incorrect ones?

Are you speaking of the ends of the seal left sticking up by any chance?
 

Also it is critically important that you use a round rod as mentioned to forcefully and evenly spread-work it into the groove as directed. the results of which may not be visible to the eye but that are important.

You said you "tapped it in".
 
I used the side of a socket against the seal and tapped it with a light hammer. I'm afraid that if the cord is not completely in place, the cap may not seat properly in place allowing little to no support for the bearing.
 
(quoted from post at 15:28:22 03/25/17) I used the side of a socket against the seal and tapped it with a light hammer. I'm afraid that if the cord is not completely in place, the cap may not seat properly in place allowing little to no support for the bearing.

I just got home and dug out an old '48 to '51 Chev Truck Shop Manual.

Here are the exact words:

2. Make sure the groove is clean
3. Insert the seal into the groove with the fingers
4. Using a rounded tool, [b:8eb522546c]ROLL[/b:8eb522546c] the seal into the groove
NOTE; When rolling the seal start at one end and roll it to the center of the groove. Then start at the other end, again roll toward the center.

The illustration shows the guy using a 6" long smooth 3/8" rod.

I forgot to say "roll" the first time. Like watching your mother with a rolling pin. :)

Your realistic worry would be this, assuming the seal is correct and it probably is (it flattens out quite a bit when the high cap torque flattens it to conform to the curve of the crankshaft flange). . . But, if it isn't thoroughly ROLLED deep into the groove then the cap torque may sink it very slightly deeper into the groove, decreasing the pressure where 4 wick ends meet at the cap to block face, thus resulting in leakage at those point.

having a seal not thoroughly pressure rolled (imagine how much pressure torquing the cap will place on it)
AND an imperfect cutting of the ends are the two main reasons for leakage at the joints.

Best ways for trimming the seal ends . .
A block of wood the same diameter as the crankshaft flange
to hold the seal firmly in place while the ends are cut -- cutting towards the wood of course with a brand new thin blade.
An ideal obviously would be having another old crankshaft so you could rest the flange in the cap.

What I did on my Chev 235, was leave the wick/rope seal 1/32" proud of the cap, then I kind of pinched it into a dull pyramid cause I wanted to make sure none of it got between where the cap meets the block. I might have even put a dot of Permatex #2 on that pyramid . . . I can't remember.

For the half of the seal in the block, I had the crank flange laying heavily on it and I cut it flush with the block face.

Be really careful to keep the razor knife perfectly parallel to the block and cap surfaces when cutting; i.e., use two hands
with finger pressure on the blade itself to keep it flat.

In my case the block was out and upside down on a table, so I was able to first ROLL the seal into the block groove as well before trimming it.
In your case, after pulling and crank-assist rolling the wick up and around and into the block groove, bringing the crank up snug again, via the other main caps before cutting the ends would be a good idea.
 

Meanwhile after all that . . .
If that photo is what your seal actually looks like AFTER being rolled or however pressed into the groove, then I'd say it IS the incorrect seal.

Sorry about that.

Oh well, the rest of the theory still applies :)

Terry
 
Thanks guys, I didn't like the look of it. It is completely compacted into the groove and the entire half of the weaved outer layer is left. I figured that there wasn't anywhere for it to go and not allow the cap to seat properly and causing a spun bearing. I guess I need to order the neoprene seal. Thanks again
 
(quoted from post at 11:26:27 03/26/17) Thanks guys, I didn't like the look of it. It is completely compacted into the groove and the entire half of the weaved outer layer is left. I figured that there wasn't anywhere for it to go and not allow the cap to seat properly and causing a spun bearing. I guess I need to order the neoprene seal. Thanks again

You're very welcome.
It's probably the correct wick seal for my 235 Chev 6. :D

Bigger cap, wider groove. (?)
I'll go down to my shop and measure the crank flange on a spare Chev shaft I have.

Yes, the neoprene one is the way to go.

Terry
 
Thanks again. I thought I could get by with loosening the caps and packing a little extra in the top half and replacing the lower. It worked on my old ford 390 engine. I probably had the correct cord then. :?
 

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