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- 05.29.2012 #1Light Load Member
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Need help with Cat 3406C rear main seal
Working on what's supposed to be a 4CK Cat 3406C motor. Got the front main seal installed no problem and working on the rear main on now and having trouble. The part number I have for the front and rear seal is 1425868, the CAT part # is 2W-1734 and that supposedly crosses over to 1425868.
The seal seems to be the right one however there is a lip on the rear of the crankshaft that is the same diameter as the inner part of the rear main seal and that is preventing the seal from going on anymore than maybe 1/16"
Here's a few photos:
In this photo you can see the lip on the crank

This is as far as the seal goes on

This is the seal and the crank

The front seal went on no problem then again there was no lip on the front of the crank.
Any ideas? We've tried everything we can think of and we're just about at wit's end.
Thanks for the help!
- 05.29.2012 #2Road Train Member
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Is it the wear sleeve off of the old seal by chance? To me thats what it looks like.
- 05.29.2012 #3Light Load Member
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- 05.29.2012 #4Road Train Member
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Carefully cut through it with a small chisel then pry it off. Then go and borrow an installer tool from a shop to install the new seal assy.
- 05.29.2012 #5Road Train Member
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Did the old seal look just like the new one? If so and the wear sleeve is still on the old seal then that is part of the crank.
- 05.29.2012 #6Light Load Member
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The old seal was a little bit different looking, then again it came out in about 6 different pieces. I'm about 99% sure this is part of the crank itself. It's one continuous piece all the way around the crank with no breaks or splits in it.
Here's two hi res photos of the lip:

- 05.29.2012 #7Road Train Member
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The wear ring is one continuous piece press fit onto the crank. You always have to work them off during seal replacement. The installer tool is necessary to install the new seal assembly because the wear ring is press fit.
- 05.29.2012 #8Light Load Member
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Gotcha. I take it that the installer tool just uses brute force to press the new seal over and past the wear ring or does the wear ring get removed and reinstalled?
The manual for this engine really doesn't go into too much detail on this subject. Thanks again for the help!
- 05.29.2012 #9Road Train Member
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The wear ring is already on the new seal, it doesn't come off. That ring that is on the crank now will have to come off in order to install the new seal.
When installing the new seal, have someone get on the front of the crank and apply back pressure against it. Once installed check to make sure the seal isn't up against the wear ring. ALso have someone move the crank back and forth just so you know its not going to rub up against.
- 05.29.2012 #10

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