Rear main bearing cap packing

[Oland]

This is a question about the two round 3/8" rubber rods that fit in the rear main bearing cap. P/N WO-637790.

First question is: What is the function? Is it only a positioning part or has it also got an oil sealing function?

I tried to push it down the hole after mounting the cap but it was impossible. Then I did a mistake and tried to put in place together with the cap and by doing this I ruined one of the rods.

The diameter of my rods is .38". The holes are .37. I found this picture:

http://willysmjeeps.com/v2/modules/gallery/albums/album134/G503_637790_Main_Bearing_Cap_Packing_low_res_001.sized.jpg

which shows the diameter is supposed to be between .366 to .370 so I guess that explains my trouble, my packings are too thick.

With respect to my first question; can I make a new rod out of e.g. PTFE? That would be possible to turn in my lathe. Or does it have to be rubber?

(I searched the forum for discussions about these packings but I could not find anything written about them.)

/Oland
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Jeep M38 1952
GMC CCKW 353 1945
International M9A1 1942

[53a1]

I just finished my engine a few weeks ago and from what I saw they should be a little smaller than the hole in the bearing cap. They are used to seal between the cap and the block and when you tighten down the oil pan it seals. I don't use RTV very often but in this case I coated the seal RTV and pushed it down. This forces some of the RTV into the gap between the block and cap.

As far as my results, I used the rope seal that came with the kit and the RTV and I have zero leaks from the rear after an hour of run time. We will see how things go after time progresses.

As far as alternative materials, I don't know. Probably a rope seal would work if you go the RTV route. If you are like me I have a lot of old gasket marterials laying around and would use something I have on hand.
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'53 M38A1 X2

[Oland]

Thank you 53a1.

I now understand how they are supposed to work, by compression. I can say the previous motor restoration missed that, as the rods were cut flush with the block.

OK, so this morning I managed to first repair the damaged rods as they were badly cut by my improper tries earlier. I glued them with Superglue which is very effective on rubber.

Secondly I managed to grind down the diameter by putting the rods in my lathe, run it slow (100rpm) and grind off the necessary amount by wrapping some coarse (80) sandpaper around the turning rod. It worked perfect! The rods now can be pushed down easily.

I cut them off so they protrude 1/4" as per the book and I will use some RTV this afternoon to finally put them in position.

Let's hope it works
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Jeep M38 1952
GMC CCKW 353 1945
International M9A1 1942

[53a1]

Should work fine. There's not much to them. Remember to double check everything before you put the pan back on. One thing about the f-134 is they have floating bearing caps (no posistioning pins like on the L6-226. Remember to bring the crank up against the front bearing before you snug down the caps then set your end play. The cj3b page has a good engine tutorial and that's one of the sources I used.
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'53 M38A1 X2