Truck is running great, but won’t drive

[TNBrett]

So, if the truck is running, and on the ground and you let the clutch out completely in reverse, does it stall out, or does it spin the tires?

 

[Nimainimai]

It would stall out if I completely let off the clutch.

 

[Nimainimai]

It would stall out if I completely let off the clutch while on the ground. With the rear in the air, it doesn’t stall, tires will just spin.

 

[IDIBRONCO]

So the rear tires spin while in the air whether the transmission is in neutral, or in gear? What about the front tires? Do they also spin while in the air? When you mentioned earlier that the tires spin while in the air, when in neutral, I was assuming that you were talking about all four tires spinning. Now that you say, specifically, the rear tires are the ones that are in the air, I'm leaning to you have a problem with the front brakes. The front tires are the only thing that hasn't changed during your tests. They have (apparently) always been on the ground. Since they have always been on the ground, they must be what isn't turning. After sitting for 5 years, funny things can happen, even to brakes, even in Phoenix, AZ.

 

[IDIBRONCO]

One more thing to add. I know that you didn't mention it, but is there some type of brake lock on your truck? Back in the late 90's I swapped a 6.2 in a Square Body Chevy. It had a four speed transmission. The truck would barely move under heavy throttle after the new engine was in the truck. We called the owner and she said that there was a brake lock that locked up the front brakes. We couldn't get it to unlock and that meant that I didn't have to test drive that particular truck (it was a HUGE POS and I was happy about that). The owner had some choice words for us (she was a HUGE B-word)., but that didn't change the fact that we couldn't unlock the front brakes. We didn't notice it because she trailered it to us, not running. We picked up the front end with our forklift and pushed it into the shop that way. She came to get ti after hours so I wasn't there to see her load it back on the trailer. Long story, but it may be possible if you bought the truck and then had to do some work on it before you could drive it. I also know that it's a very slim chance, but I thought I'd throw it out anyway.

 

[gnathv]

I’m to slow typing

 

[IDIBRONCO]

It happens sometimes.

 

[Nimainimai]

Hey all, sorry I didn’t explain it better earlier. Both front and rear tires spin by hand when up in the air. I can also push the truck (in neutral) pretty easily. I haven’t tried to power the front wheels, but the back turn with engine power (while up in the air) I will look at brakes a little more this weekend and then probably tear into the T case after that.

 

[sjwelds]

Supposing your driveshaft is too long and is somehow binding when the truck is on the ground, but when you raise it it unbinds... Just a WAG

 

[asmith]

Just another WAG. maybe the clutch is so worn out it is slipping? it has a enough friction to turn the wheels in the air, but once the weight of the truck is on it, it cant move the truck. no idea just throwing things out there. i cant wait to see what it is.

 

[lotzagoodstuff]

Just another WAG. maybe the clutch is so worn out it is slipping? it has a enough friction to turn the wheels in the air, but once the weight of the truck is on it, it cant move the truck. no idea just throwing things out there. i cant wait to see what it is.

This is a pretty good lead, only every slipping clutch I’ve ever been around stunk liked burning friction material. I still like the clutch as a suspect theory.

 

[Big Bart]

Ok so truck rolls. Wheels spin off the ground. But when in gear and on the ground it stalls the engine.

Some thoughts.

1) Pull the drums and see if there is a bunch of rust or dust that binds up when the axles are loaded up due to weight.
2) I am trying to think if your spider gears in the axle where rusted up. If so when in the air could they rotate the tires in opposite directions, but on the ground the spider gears can’t rotate opposite and rather lock up. (Feeling like the brakes are on.) Trying to picture in my head how they rotate.
3) I once bought a old Ford Bronco. When we got it running the guy put a different axle gear ratio in the front. So in 4wd it would lock up as the wheels would not spin at the same rate.

This one is a little perplexing. Let us know what you find.

 

[TNBrett]

Just another WAG. maybe the clutch is so worn out it is slipping? it has a enough friction to turn the wheels in the air, but once the weight of the truck is on it, it cant move the truck. no idea just throwing things out there. i cant wait to see what it is.

This is where I was going. If the engine can drive the rear tires when they are in the air, it seems like the issue shouldn’t be in the rear end or drive shaft. I think I would try and move the truck again under its own power. This time let out the clutch all the way. It should either move, stall, spin the rear tires, or drag whatever front tire doesn’t roll. If you don’t get one of these results your clutch is slipping.

 

[Selahdoor]

I would make sure it isn't in 4wd.

Start it. Push the clutch in. Put it in 1st. And let the clutch out all the way, slowly.

If it stalls, just do it several times, to see if it changes. And to see if the problem makes itself apparent.

If it just keeps stalling, and nothing changes, let the clutch all out quickly.

Do this several times. Trying to break loose whatever is stuck.

 

[Booyah45828]

With it off, in neutral, and on stands on the rear axle, can you get the driveshaft to move?

Engine running, trans in neutral, transfer case in 2 hi, release the clutch pedal, what does it do?