Help diagnosing AWD problem please.

[syntax]

Well something has gone horribly wrong on my 91 Sy, heres what I know so far.
Started as a rotational squeeking noise, At first i thought for sure it was the propshaft going bad so I put all 4 in the air to remove propshaft, thats when I Ran it in the air to test it, heres what it is doing:

All 4 will start to spin when truck is turned on and put in gear, But randomly one of the 4 will start to spin 3-4 times faster than the others,. then One of the fronts will stop moving completely while the other 3 continue to turn at different speeds. Another thing i noticed is when it was on the ground, when i put it in to drive it would SLAM forward like it was idling at 2000 rpm. Im going to pull the shaft anyway since its in the air but does anyone think trhis sounds like a TC or diff problem? Im a newbie at awd systems so any other things I can do to diagnoise the problem ?

 

['JustDreamin']

Re: Help diagnosing AWD problem please.

Well something has gone horribly wrong on my 91 Sy, heres what I know so far.
Started as a rotational squeeking noise, At first i thought for sure it was the propshaft going bad so I put all 4 in the air to remove propshaft, thats when I Ran it in the air to test it, heres what it is doing:

All 4 will start to spin when truck is turned on and put in gear, But randomly one of the 4 will start to spin 3-4 times faster than the others,. then One of the fronts will stop moving completely while the other 3 continue to turn at different speeds. Another thing i noticed is when it was on the ground, when i put it in to drive it would SLAM forward like it was idling at 2000 rpm. Im going to pull the shaft anyway since its in the air but does anyone think trhis sounds like a TC or diff problem? Im a newbie at awd systems so any other things I can do to diagnoise the problem ?

I'd be suspect of whichever front corner stops (if it's consistent). That tells me something in that corner's driveline has more drag than the other corner. I'd inspect things like axle shafts (CV's) and wheelbearings (they're sealed / not adjustable, so you can't take them apart, but you can check them for play, leaking grease, etc).

'JustDreamin'

 

[syntax]

Re: Help diagnosing AWD problem please.

Its not consistent justdreaming, also when I had just the fronts in the air I turned the fronts by hand and no squeeking, When i got all 4 in the air and ran them the squeeking started agian, makes me think its not a cv or bearing.

 

[syntax]

Re: Help diagnosing AWD problem please.

with all 4 in the Air and in any gear I cannot get the propshaft to turn by turning any of the wheels ( althought i dont know if it is supposed to function like this)

 

[Loeryder]

Re: Help diagnosing AWD problem please.

In neutral have someone hold one of the front tires and spin the other.
Does that spin the propshaft?

Any noises?

Try the same on the rear.

I would pull the P Shaft and take it for a spin.

 

[syntax]

Re: Help diagnosing AWD problem please.

OK, I took the propshaft out and the noise has stopped, I'm not sure, but I can assume that this means the driveshaft is bad, (can it still mean tc or diff is bad?) If everything I posted about what the truck was doing in the air on post one is normal, then I guess i CAN assume is the propshaft, although in my hand the joints felt fine, maybe I will grease it up and put it back in and see if noise stops, Can anyone tell me if the symptoms I posted in post 1 are normal for all 4 wheels in the air?

 

[George Blake]

Re: Help diagnosing AWD problem please.

It doesn't mean the prop is bad. It means something is either wrong with the front diff or the transfercase. I'm betting it's the front diff. See if there is any fluid in it.

 

[syntax]

Re: Help diagnosing AWD problem please.

What about the symptoms makes you beleive its the diff george? Where do I check it for fluid ?

 

[Black Knight]

Re: Help diagnosing AWD problem please.

There's a fill plug on the front of it. Take the bolt out and stick your finger in there and see if you can touch any fluid, if not it's probably too low.