4x4 won't engage..

[GhettoPathy91]

Hey there,

I'm asking a question for a friend regarding a 95 Isuzu rodeo. Basically 4x4 won't engage. The front driveshaft spins when in 4 low and hi, the hubs lock which in turn spin the cv axels when off the ground. But the front diff doesn't feel connected. With the hubs locked and 4 low engaged, I spin the front tire and the one on the other side doesn't move. Could the diff be bad or something disconnected inside?

[ebayfish]

Your spinning it manually? I believe that means you have a full open from differential. If you broke a ring gear or something inside the housing, I'm sure you hear it or the front end would have locked up.

Edited December 27, 2014 by ebayfish

[GhettoPathy91]

Yes but wouldn't an open diff entail the wheels spinning opposite ways? This isn't happening. There isn't noise coming from the diff.

[Slartibartfast]

4x4 engaged, trans locked, one wheel spinning, the other should spin the other way. One shaft on a diff should never be able to turn without turning at least one of the others. Blown spiders would be my guess.

I would've expected a knackered front end to make noise and cause all kinds of drivability issues, but my dad's Tundra sheared its front pinion off the other day (we're still scratching our heads about how and why), and it drove and sounded fine so long as the transfer was in 2HI.

 

I have heard of some axles having a vacuum disconnect, which disengages something in the front diff of some domestic rigs. I don't know if Isuzus use it too, but if they do, and it's out, I imagine it would act like what you're seeing. Worth checking into, anyway.