The rear diff on my Ranger is howling really loud. I'm about 99% sure it's bad pinion bearings. You can here the howling in this video:
So this past weekend I did some diagnosing. First I jacked up the rear, removed the rear tires, started the truck up and let it run in gear. The sound was definitely coming from the center section, not the wheel bearings. Then, I put the tires back on, removed the rear driveshaft, and drove around the block in 4wd (essentially making the truck a front wheel drive). The howling was 99% gone. I think that’s sufficient to rule out the wheel bearings and point towards pinion bearings.
Then I jacked the truck up again and started rotating the pinion by hand. I get a loud clunking which is amplified without the driveshaft. With the driveshaft installed, it’s much less pronounced. You can see what I mean in this video:
Next, I pop the cover off to see if there are any broken chunks or anything in there. There’s nothing broken and no glaringly obvious problems. No chipped teeth on the ring or pinion. The only problem I saw was a thin layer of sludge on the diff cover (you can see where I rubbed a section clean with a rag. That’s what it’s supposed to look like. The rest is darker because of the sludge.)
And some fine particles:
I got some gear marking compound and checked the pattern too. It looks pretty good, although I’m not sure what’s up with that diagonal line right in the middle:
And another video of the clunking with the cover off. You can hear it clunking at the same point as I rocked it back and forth.
Well, why would a truck with only 48k miles on it already have bad pinion bearings? About 4 years and 25k miles ago, I had a SMALL drip from the pinion seal, so I had a shop replace it. I'm guessing they didn’t torque the pinion nut down properly and messed up the bearing preload.
So, I think my best and cheapest option is to get a junkyard axle. I can get one with only 52k miles on it for $450, or one with 100k miles for about $100. I want to keep this axle and use this as an opportunity to learn how to rebuild a differential. I can rebuild it in my spare time without having the truck down and then keep it as a spare. And I plan on installing a crush sleeve eliminator on it so I change the pinion seal and not worry about screwing up the preload.
So this past weekend I did some diagnosing. First I jacked up the rear, removed the rear tires, started the truck up and let it run in gear. The sound was definitely coming from the center section, not the wheel bearings. Then, I put the tires back on, removed the rear driveshaft, and drove around the block in 4wd (essentially making the truck a front wheel drive). The howling was 99% gone. I think that’s sufficient to rule out the wheel bearings and point towards pinion bearings.
Then I jacked the truck up again and started rotating the pinion by hand. I get a loud clunking which is amplified without the driveshaft. With the driveshaft installed, it’s much less pronounced. You can see what I mean in this video:
Next, I pop the cover off to see if there are any broken chunks or anything in there. There’s nothing broken and no glaringly obvious problems. No chipped teeth on the ring or pinion. The only problem I saw was a thin layer of sludge on the diff cover (you can see where I rubbed a section clean with a rag. That’s what it’s supposed to look like. The rest is darker because of the sludge.)
And some fine particles:
I got some gear marking compound and checked the pattern too. It looks pretty good, although I’m not sure what’s up with that diagonal line right in the middle:
And another video of the clunking with the cover off. You can hear it clunking at the same point as I rocked it back and forth.
Well, why would a truck with only 48k miles on it already have bad pinion bearings? About 4 years and 25k miles ago, I had a SMALL drip from the pinion seal, so I had a shop replace it. I'm guessing they didn’t torque the pinion nut down properly and messed up the bearing preload.
So, I think my best and cheapest option is to get a junkyard axle. I can get one with only 52k miles on it for $450, or one with 100k miles for about $100. I want to keep this axle and use this as an opportunity to learn how to rebuild a differential. I can rebuild it in my spare time without having the truck down and then keep it as a spare. And I plan on installing a crush sleeve eliminator on it so I change the pinion seal and not worry about screwing up the preload.
