Pinion Seal replacement 2016 1 ton dually, 2WD...

[68Gold/white]

I service and repair a fleet of vehicles. I have done a lot of things, replaced a lot of pinion seals, never had one give me any trouble.........

2016 One ton dually pickup (2wd), tows cattle trailers, has a heavy flat bed on it.

I had been under the weather last 3 months of 2019, and not too terribly well from Jan-Mar of this year (kidney stones).

This pickup gets boat load of miles put on it. I was unable to service it the last two times it was in need, SOOO they take it to an oil change place. The oil change experts managed to install a new air filter. I am sure it didn't get any grease, tires were not checked and the differential wasn't checked, obviously...When I check the differential oil, I stick my pocket screwdriver in the oil fill hole. I checked this one several times. After sticking screwdriver straight down in hole, I got about half a drip on it...well crap I say to myself. I slide around on other side of differential. Pinion seal had been leaking. Dust combined with oil to make a nice crust, and a LOT of it...

I replaced the pinion seal. The surface on the yoke had 2 nice grooves in it, bought a new yoke. New yoke comes with a new seal, pinion nut, and washer for nut.

Replaced seal, nut/washer and yoke, got pinion nut tightened to where old one was (for bearing pre-load on bearings, crush sleeve...). Filled it up with 75W90 synthetic gear oil, just as manual says to. One thing I did notice when I poured the drain pan into my used oil tank. There were a lot of little chunks of something at the bottom of the drain pan. The chunks are gritty, and non metallic. I let the diff drain after I pulled the cover, I then sprayed down the gear area with brake cleaner. THis pickup DOES get driven on unpaved roads, a lot!!!

Rear end howls quite nicely, now. I have driven this pickup in the past, on test drives. It never made any noise.

My next move is???

[burnin oil]

could the grit be clutch material from the posi? I would run it a day and drain again. Maybe there is crap in the bearings that needs cleaned out still.

[68Gold/white]

Originally Posted by burnin oil

could the grit be clutch material from the posi? I would run it a day and drain again. Maybe there is crap in the bearings that needs cleaned out still.

It's not a posi. Didn't look close enough to tell if the could be a locking diff...oh well. My 2005 1/2 ton has a locking diff, has no clutshes, not sure on what 1 tons have. I will be learning more, here soon!!!


It only makes noise when you are accelerating, and accelerating even a small amount, or have your foot in it. Let off the throttle, no noise. It all tells me it's a gear problem...

Monday I am going to ruinate that new GM pinion seal, by removing it, and remove the front pinion bearing, see what it looks like. I tried to shake the drive shaft before I even took the drive shaft loose, It was tight...Pinion yoke turns freely w/ drive shaft removed.