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Rear engine main seal replacement
07-12-2012, 01:18 AM
MWrenchRear engine main seal replacement
OH Boy, this job is NOT for the faint of heart, Deep into it now and it is NOT fun. Pictures and write up to follow.
Majorly different from the 5.9L with the 4 speeds. Even Cummins is confused about what is needed. Finally have the bellhousing number so it is back to Cummins in the morning for the correct parts.
Again more later
Ed
94 30' Breakaway #3864
30-BS-6B side entry
New Cummins 5.9L, 375+ HP
Allison 6 speed
Spartan chassis
K9DVC
Tankless water heater
07-12-2012, 08:09 AM
Bill N.Y.When you tell them it is a Diesel Pusher make sure they give you the correct rear main seal - stress to them that the engine is a standard rotation and is not a reverse rotation engine.
Some rear main seals are made for reverse rotation engines and it will leak like crazy if the wrong one is installed. Those seals are easy to spot as the lip inside the seal is spiral in design.
I don't know if it matters on a Cummins, but it sure does on a Detroit.

˙ʎ˙u ןןıq- „ǝןƃuɐ ʇuǝɹǝɟɟıp ɐ ɯoɹɟ pןɹoʍ ǝɥʇ ʇɐ ʞooן ɐ ƃuıʞɐʇ sı ǝɟıן oʇ ʇǝɹɔǝs ǝɥʇ„
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 | 1990 Barth Regis Widebody 8908 0128 40RDS-C1 L-10 Cummins Allison MT647 Transmission Spartan Chassis |  | 1991 Medical Lab Conversion 9102 3709 33S-12 Ford 460 MPFI C6 Transmission Oshkosh Chassis |
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07-12-2012, 08:49 AM
MWrenchWell I found out that it is mandatory that you provide them with the bell housing number.. In my case it is 3904172. With that, Cummins can source all that is needed, seal, flex plate bolts etc.
It further appears that there is a crank extension that will have to be removed before I can get at the seal. The seal has definitely been pushed out and is kinda in pieces but they can not be removed as it is all against the extension which appears to be larger in diameter than the crank.
Will know more after I get to Cummins West this AM with the numbers.
The Harbor Freight 2000 lb trans jack works but it is a struggle with that MD3060. I also misjudged the CG of the trans so it is a bit tail heavy on the jack but I have taken precaution to safety chain everything.
More later. Pictures coming.
Ed
94 30' Breakaway #3864
30-BS-6B side entry
New Cummins 5.9L, 375+ HP
Allison 6 speed
Spartan chassis
K9DVC
Tankless water heater
07-12-2012, 09:47 PM
MWrenchOld seal is out and new seal is in. Old one came out in 5 pieces. The new seal is MUCH thicker. There was a slight mark around the crank flange but I could not feel anything rough. I think it was just a mark not a wear spot. After supper it will be torquing down the flex plate and moving the trans back into position.
Flex plate to crank bolts get torqued to 100 lb/ft, the was no evidence of loctite but I will add just a bit of blue loctite for insurance.
Still in a bit of a quandary about what I am going to do with the dipstick tube. I do not want it tight against the floor support as it was.
More later.
Ed
94 30' Breakaway #3864
30-BS-6B side entry
New Cummins 5.9L, 375+ HP
Allison 6 speed
Spartan chassis
K9DVC
Tankless water heater
07-13-2012, 09:30 AM
Jim and TereI am in absolute awe of guys like you and Gary and Bill and others that can do this stuff yourself. Little bit of envy, too.
Jim
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1985 Regal 29' Chevy 454 P32 8411 3172 29FP3B Gear Vendor 6 Speed Tranny |
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07-13-2012, 09:54 AM
MWrenchTrans is back in. WHEW!Once I got the seal in everything went smooth. I had to make a special seal driver as there was no room to hammer it in (as the book says to do) so the plate I made would bolt to the end of the crankshaft and I could tighten down and push the seal installer piece evenly. Took a little longer to do but at least I know the seal wasn't distorted by lopsided installation.
I have bent the dipstick tube for clearance with the floor. I put the tube on the floor and traced the tube along noting where the contact point was. Then I used a tubing bender to change the radius where it comes out of the trans mission and then further along put a slight bend to bring the tube back to its original routing. I haven't put it in yet, but if the drawing is right I will have about 2" of clearance to the floor now, plus I will be able to install it without lowering the transmission.
R&Ring the driveshaft now so I should have it finished by days end today.
Learned a lot this trip.
Ed
94 30' Breakaway #3864
30-BS-6B side entry
New Cummins 5.9L, 375+ HP
Allison 6 speed
Spartan chassis
K9DVC
Tankless water heater
07-13-2012, 12:38 PM
Brian And JanetEd,
Congratulations! I've done these on gas motors, including the old 2 piece chevy seals and this is a lot of work, especially on your back in awkward positions.
Brian and Janet
'93 Regency 36 ft
Cummins 8.3, Allison 6 speed, diesel genset, 100 gal. tank... OUCH$$$
Spartan Mountain Master Chassis
07-13-2012, 05:23 PM
Gary CarterCongrats Ed. Now longer going to mark you spot. Will also reduce oil consumption.
I still have a drip at the engine drain plug. Going to put a copper washer on it when I drain this fall.
'92 Barth Breakaway - 30'
5.9 Cummins (6B) 300+ HP
2000 Allison
Front entrance