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What am I doing wrong with the Rear Main Seal

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tfrazer View Drop Down
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    Posted: 22 June 2017 at 3:27am
Went for a drive today and the rear main completely went out went through the better part of 3 qts on the way home (less then 10 miles).   This is the second seal I have installed in less then 1000 miles and 2 years.   The first was a nylon seal that failed within 100 miles so i tried an OEM Rope Seal and it has lasted with only occasional drips for the last year and a half with maybe 200 miles on it.   Is this normal? or could I be doing something wrong in the installation.   

Thanks!

Ted 46 CJ2a


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Mark W. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark W. Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2017 at 4:48am
What is the condition and diameter of the sealing surface on the crank?
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1948 2A Body Customized
1949 3A W/S
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Oilleaker1 Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2017 at 12:27pm
To use a lip seal the crankshaft sealing surface needs to fall into a specified range of sizes that will allow the right surface contact. Too tight they burn up and make a disaster. Too loose, they leak bad. The surface needs to be clean and smooth. The rope seal needs to be rolled into the rear main cap and block and cut off a touch long. The frayed ends then tucked in. The rope contact surface with the crank should be lubed upon install with grease. The two side rubber sealing dowels should be put in right when you install the pan and gasket. They should be hanging out about a 1/4 inch. I permatex them and slide them in . The pan then pushes the rubber dowel up into the hole and expands it. I usually see permatex squishing out the gaps. If your crankshaft surface is all pitted, it will chew up the rope. A super sharp quality pair of scissors will cut much better than a razor blade. Ropes tend to seep or leave their mark. Just like the rest of the JeepLOL
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tfrazer View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tfrazer Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2017 at 2:28am
the crankshaft looksIt looks good to me but i dont know much.   I will take some pictures when i get it all apart.   Has anyone been able to put in a rear main without pulling the engine and crankshaft?








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Unkamonkey View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Unkamonkey Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2017 at 6:22am
Yep there at things called sneaky petes to pull in a rope seal. First I would be sure that the seal surface is right but that is sort of hard to do while the crank is still in place. We made around 5 attempts on the MB to fix the leak. that's why it ended up with a V6.
And the story goes on from there...
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Stev View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Stev Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2017 at 1:45pm
tfrazer,

I have replaced the rear main without pulling the engine on our 1946.  It was a lot of work and in the end it still leaked.  I put in one of the newer style seals.  I had to lower the crank to get the seal in and out...Ugly  

In the future, I will always just pull the engine.  It takes about the same amount of time and I think I can get better results by having full access and not have to mess around with lowering the transmission with the crank installed. 

A lot of work either way. 

Stev


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1946 CJ2A Trail Jeep (The Saint), 1948 CJ2A Lefty Restored
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