Rear main seal


For you lovers of the Class 8's and bigger.

Golden Jubilee
Golden Jubilee

Posts: 3453

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Mon Jan 23, 2017 4:26 pm

Rear main seal

Not sure why, but the rear main went out on my 9670 right after the cold snap. Don't know if starting in -20 F had anything to do with it, but wish it hadn't. Not the time of year to be pulling the trans and flywheel out outside in the weather.

Yard Art
Yard Art

Posts: 73

Joined: Thu Feb 05, 2015 8:23 pm

Location: Ogden Utahhhhh

Post Sat Jan 28, 2017 3:45 pm

Re: Rear main seal

I feel your pain. the old truck is in the garage but the others are on the driveway. Several years back I was putting a timing chain on a Chev 350 that was in the truck. In the late evening during a snow storm. Had to drive the truck to work the next morning.
Help! I'm stuck in the garage and I can't seem to pull myself out.

Nothing better than a nap on the creeper under the old truck.

Golden Jubilee
Golden Jubilee

Posts: 3453

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Tue Jan 31, 2017 12:40 pm

Re: Rear main seal

Got the rear main in, but couldn't get the shift linkage apart and had to take the whole thing from the cab to the trans, off. In the process, found one of the swivel joints on the verge of failure. They are made just like a tie rod end on a car, and had about 1/2" of play on the ball-socket, surprised it hadn't failed. Such is the problem when you pay someone else to do PM service, things that you would see go un-mentioned by grease monkeys.
Since Cabovers have been out of the US market for close to 20 years, finding new shifter parts was a challenge. None of the new Eaton transmission parts books cover the old remote shifters. A day of digging found both an Eaton part number and an IHC part number. Eaton part number went no where, had to wait till Monday to get Check the IHC part number, which had been superseded, and got the new number as well as a new Eaton number.
With computers making things like cross-reference quick, one would think that when I entered the old part number into Eaton's website, I should have been directed to the current number, but no!
New part is ordered, so hope it will get here soon.
Cold to be pulling transmission out side. My air tool freeze and my fingers get fumbally.

Golden Jubilee
Golden Jubilee

Posts: 3453

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Fri Feb 10, 2017 8:59 pm

Re: Rear main seal

It turns out the Eaton number has been updated and all the parts are available. Long and short of it is the rear main is replaced, new lube hose for the throw-out bearing, new torque limiting clutch brake, new power feed cable from the alternator to the cab, and new shifter parts are installed.
It is a funny thing how you never notice how loose things are getting until you replace with new tight parts. The shift is much "crisper" and rivals a conventional truck with the shift rod straight into the trans.
I also went thru are re-sealed the fuel pump. Whoever built the pump really made a "pigs breakfast" of the job, and I doubt it ever worked as it should.
It was my 1st time getting as deep into a Cummins AFC pump, but I had some "guidance" from some old hands on another site. Starts easier with less smoke and seams to have more power. NO leaks! More ever I was able to correct the problems/mistakes of the previous builder. I have 5 Cummins PT pumps (well actually 6) The one I was in was the latest generation with the "shaped port" AFC and was a bit different than I was used to. I have 4 other 1st gen AFC and one PTG that I keep around for parts only. I feel a lot more confident working on them now.

Site Admin
Site Admin

Posts: 4581

Joined: Thu Nov 29, 2012 9:10 am

Location: Nampa, Idaho

Post Fri Feb 10, 2017 11:40 pm

Re: Rear main seal

Always good to find improvements to something you need fixed.
User avatar

Golden Jubilee
Golden Jubilee

Posts: 515

Joined: Sat Oct 26, 2013 10:11 am

Location: SW Washington

Post Sat Feb 25, 2017 12:41 pm

Re: Rear main seal

The PT system has been explained to me but... I just know when I step on the pedal it works.
'52 L-160 dump truck
'57 RD-405
'58 Allis Chalmers D grader

Golden Jubilee
Golden Jubilee

Posts: 3453

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Sat Feb 25, 2017 12:53 pm

Re: Rear main seal


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