Weldingiron

I recently purchased an '88 and I've run into an issue. I was driving down a dirt road with 4x4 engaged (manual hubs locked) when all the sudden I started slowing down and it felt almost like I'd run into a snow bank. I stopped and when I tried to go again the truck wouldn't move. I got out and saw that the front diff was smoking. I unlocked the hubs got back in and the truck still had problems moving forward with the selector in 4x4. I put it in 2 high and had no issues. So with it in 2 hi I locked the hubs and the same thing.

I'm thinking maybe there wasn't any oil in the diff and I fried it. Any insight or trouble shooting tips? Thanks!

GhostriderI

Check your gear oil (all of them) it may just be real low and has over heated, if after you top it off the problem still existed there is a problem. IMHO

Weldingiron

Thanks! It does sound like it could be the diff though?

GhostriderI

Hoping it just got warm and bound and will release as it cools

Weldingiron

I tried locking the hubs on the way to work today and still can't move with them engaged. Or with the stick in 4x4 without the hubs engaged.

Manuellabour247

I had my 75 rear end lock up from low oil in high school. Have your dif seals been leaking? If so, might be time to rebuild it. You could try just replacing the bearings for the ring hear assembly, but that would just be a bandaid. If those bearings are shot you might check the rest to include your driveshaft.

Weldingiron

When I open the differential should it be pretty obvious if the bearings are bad? I apologize for my ignorance, this is the first vehicle I've had drivetrain issues with. With my 85 it's always the engine I'm working on lol

Manuellabour247

You can smell burnt oil. That's pretty obvious when it rapes your nose. Lol. Other than that, you won't be able to turn the ring gear. That will tell you it's the carrier bearings. When you start to pull it apart you can look at the seals too.

Weldingiron

I put gear oil the front diff, drove it around a bit and then put it in 4x4. It is no longer locked but has a rattle/rumble sound coming from the front end when I drive. needless to say, I didn't go very far in 4x4.

GhostriderI

Might be time to start rounding up parts for a rebuild. It should hold as is for normal driving. Did you also top off your transfer case and rear end as well? If the front was low I would top off everything, also get a grease gun and lube the u-joints that have fittings they may also be dry.

Hope this helps