4wd does not work. i have manual hubs so its not the vacuum lines and actuator. what can i do to troubleshoot the problem? ive posted this a few times and havnt got one decent response. there has got to be something i can do? please help. i have a trip coming up and need to be working right.

 

Ok you should have a few things to check. first lock your hubs the put the truck in gear and in 4wd. get under the truck and spin the front drive shaft. Does it spin free? If so are you front axles spinning as well? If that is the case then you have something wrong with your hubs. If it spins free but the axles do not move. It may be something in the diff. It it does not spin then you may have and issue in your t case. I am no expert but follow the path from the engine to the transmision to the t case to your diffs to you wheels. hope this helps

 

when 4wd is engaged and hubs are locked, the drive shaft will not spin, but the 1/2 shafts will spin (opposite of each other). when i lift one tire off the ground in 4wd the tire will spin. i guess this means its a problem with the diff? what could be wrong with it? also, the truck has very rarely been put into 4wd, so wear or abuse should not be an issue. ps. i take it that when 4wd IS engaged, shafts and tires are NOT supposed to spin? is that right?

 

^ +1. this is what you need to do.

 

Ok when 4wd is engaged and the hubs are locked the drive shaft had better not spin, you're good there so we can rule out the t-case.

The half shafts both spin by hand? I would think you could spin one or the other but not both. I'll go out to my rig during lunch and try it.

Whey you lift a tire on the front end, with the hubs locked and 4wd engaged, and spin it all that means is that you have an open front differential.

This may sound like a stupid question but how do you know it isn't working?

 

sounds like your hubs are not locking or working correctly. when you lock the hubs you should be able to reach around the tire and grab the cv--it should not turn. do the same with the hubs switched to free--they should turn freely. pull off the switch and locking mechanism on the hubs, have a look to see how they work (it's pretty obvious) and make sure they are assembled correctly.

 

i bet its working or you have a bad axle on one side causing the diff to send power that way remeber it chooses the path of least resitance I.E. why we buy lockers.

 

or the 4wd light bulb is out

 

After re-reading this I have to agree with Murakami. It sounds like your hubs are not engaging.

 

When I first bought my 86 runner years ago I discovered the 4wd didn't work after getting into a pretty good sized mud hole. After the recovery (shoveling a path with an old license plate and setting rocks in the mud for traction) I pulled the hubs to discover that someone had put an extra spring in the passenger side hub. The spring interfered with the hub engaging properly. Removed spring and 4wd worked fine. I am not saying that this is what is wrong. Just another vote for checking your hubs.

 

if your tires are on the ground, and you've locked the hubs, but you can still turn the cv shafts with your hand, then they're not really locked.

to test your hubs: in 2wd, get under, turn your shafts. they turn in opposite directions. lock one hub. when you try to turn the cv shafts, you should hear that hub clank and stop it from turning. unlock and do the same for the other side. this should isolate a bad one, or identify both as bad/good.

 

ok. i have checked both hubs, they seem be working fine. CB shafts will not spin when hubs are locked. the reason i have to believe my 4wdis not working is i got stuck in a ditch and noticed only the rears spinning, nothing up front. i managed to get out on my own, but with no help from 4wd.

 

i don't know man. when you noticed the wheels spinning were you sticking your head out the driver's side window? maybe the driver's side wasn't spinning and the other side was. this can happen sometimes if your diffs aren't locked.

 

Why don't you drop the rear drive shaft and go on 4wd? that's the easy and surely way to find out.

 

well i'd say the next easiest thing to do is get the truck all four off the ground, and put it in gear.

get 4 jack stands, or go to a garage with a lift and stay in the truck. get off the ground by lifting at the frame, and put it in gear. when you let the clutch out, it could shift the truck on the lift a little. be careful.

with 4 off the ground, you should get opposite wheels spinning if i remember correctly. like front right and left rear.

let us know how it goes. i'm interested in how this turns out for ya