Front Diff humming

[supertremendous]

so I have a 1992 explorer XLT that was sitting at 100k miles for 6 months before i bought it and since then ive put on maybe 2k more. anyways the front the diff is humming really bad at about 10km/h up. the 4x4 didnt work when i bought it (transfercase motor) after i replaced it, put it into 4hi and took it around the block. now the noise is WAY louder and im wondering if the front diff is toast or the automatic hubs didnt disengage.

 

[natenkiki2004]

When you say "around the block", you weren't driving on pavement were you?

 

[Roadrunner777]

Dif fluid? Could be a wheel or hub bearing.

 

[supertremendous]

Yea it was on pavement around my shop.

 

[Wolfie_85]

Try reversing it about 10 feet, make sure the 4x4 light is off when doing this. That should disengage it, if that's the issue. Driving it in 4 wheel on dry pavement can damage it. Just a heads-up.

 

[natenkiki2004]

Definitely not good to do that. That said, it seems to me not a lot of people would replace spindle bearings. Mine were toast and obviously factory. Nasty humming/grinding up front with even 1 hub locked, regardless of whether or not it was in 2/4wd. They're a pain to get out but cheap to replace and re-install. It's hard to punch them out, easier to get a chisel in and split the bearing and live with the gouging in the spindle.

 

[mezrein]

Call me uneducated, but why is it bad to drive in 4x4 on dry pavement?

 

[Wolfie_85]

It's bad to use 4-wheel on dry pavement because it can damage the system. They say to use it in low traction situations only because it spins the front and rear at different speeds, and that can chew things up, because it can't slip to compensate.