TJE

Just got home and found oil all over the frame! start the truck and it's dripping oil from the front of the bell housing. Just wondering if there is any CAUSE that I should be concerned about on the rear main?? Or is it just age? What else besides age could be the culprit?

Thanks, Tony

Jim Lane

I have seen rear main seals leak when the main bearings were so bad the crankshaft would slop but that would never happen on a Cummins, too much overkill.

Usually the seal just gets brittle and leaks from age, think how long it has been in service holding back oil.

Also check your tappet cover at the rear, mine started leaking a little and then it let loose, left a puddle about a foot in diameter every time I stopped.

My rear main seal leaked off and on for over a year until I finally had it replaced when the transmission was out.

Jim

thrashingcows

That's the one thing that sucks about the cummins motor. You have to pull the tranny, flex plate, engine adapter etc....to change it out.

The rear main seal on my 93 motor had part of the inner lip broken and spit out between the crank and the outer seal...yup needed to be replaced.

j_martin

The only seal I ever saw that could be replaced without pulling the flywheel was a rope seal. You still had to pull the pan and the rear main cap. the seal itself was pretty primitive, but back then you figured on a complete overhaul every 50,000 miles or so.

thrashingcows

Pulling the oil pan, and popping of the rear main cap is a lot easier then the tranny and all the hardware....especially a 4wd.

1972RedNeck

Yes, but the seals don't run near as long. I'll take the one piece any day.

fatt

The engine adaptor doesn't need to come off to replace the rear main. I just did mine about two months ago and I only pulled the trans and flexplate.

torquefan

X2. Done dozens of them and never removed the adaptor plate.

TJE

Well got the truck scheduled for the big job.....is there any LEGITIMATE differences in where I buy the seal kit? I'm finding from 49.00 to 87.00 bucks

Thanks, Tony

Jim Lane

I got mine from Cummins and not the Auto Parts.

Get the instructions from the FSM to follow, handled improperly and the seal can die a quick death.

TJE

anyone have the FSM instructions on this? I know I need to buy my own FSM but money is tight at the moment.

Thanks, Tony

Bob L

Ditto ! Good advise Jim.....

Do it right the first time, why chance it. Get the Cummins seal.
Crankshaft Seal Kit- Cummins
Part #3934486 Cost $69.55 A/O Sept. 2012

Must be installed dry and absolutely clean.

TJE

Thanks, guys

Jim Lane

Tony,
Not going to be home today but I can get it tonight.
Jim

Jim Lane

PM me with your e-mail address and I can loan you a copy