I have an 89 pickup, 3vze manual transmission 4x4. I recently towed a car for like 10 hours and I noticed my truck making a high pitched whine of some sort. I cant hear it very well when my windows are up but when they are open i hear the noise. it is kinda like the noise that the pickup makes in reverse but a lot quieter. I notice it as long as I am moving. It doesnt seem to make a difference whether or not i am in gear or accelerating, though it does get quieter as i slow down. Any Ideas?

Thanks guys

 

U-Joint/s?
Axle Bearing?
Glazed brake shoe/s from towing?
Noise from the front or rear?

 

Yup, check those plus gear oil in trans and diffs.

 

i am thinking it is coming from the rear. I will put the thing up on a jack tonight and see if i can get close with my ear. it only happens while i am moving. the brakes dont seem to influence it. I thought it was my rear diff but after seeing it was very low on oil i added a half quart or so and the noise didnt change at all. does that rule anything out or am I still in the same boat? Is a carrier bearing possible?

 

10 hours of towing with a "very low on oil" diff is not a happy thing - but it could whistle. If it's the diff, and I suspect it is, the whistle comes from the already damaged pieces working against each other.

Does the whistle change in correlation to speed? Was the load heavy? Were you pulling hills?

 

It could be the outer pinion bearing.

 

So... I put the rear differential up on a jack yesterday and put her in 5th so everything would spin. the noise is coming from the transmission as far as i can tell. Just behind the engine. It doesnt change noise when i push the clutch at all though so I assume it cant be the throw-out bearing right?

 

Oh and my bad Wolves, I know pulling a load on low oil is the sign of an idiot but it happened haha.... and yet the load was heavy. probably 5400lbs plus a car dolly. and there were a couple small hills but I think the trip was flat for the most part. I will have to admit the poor pickup did struggle pulling the whole time. the trip is usually 5 hours long and in order to stay in a lower gear the whole way I doubled the drive time. It was rough. Probably not wise but I have been pulling little cars (2500lbs) over and over gain and it was doing fine.

 

No "idiot" from me, I spoke from experience. Got a 66 Chev Pu in the early 90s for hauling race cars around. It came from my g/f's father and was well maintained. Before the first trip to the Runoffs, from CA to Atlanta I checked "everything". "Everything" was so perfect that I skipped the diff. Made it TO Atlanta and at the end of the week barely made it to Jackson MS. Where I spent a couple days replacing the whole rear end. Lucky me the nice people at the towing service fed me and the g/f one night and let me use their shop to work in. The first sympton was the gear shift lever starting to do a hula kind of thing, then cane the whine.

Good luck on the R & R.

 

Thanks for that description wolves. The hula thing had me curious because mine was doing that. I had originally lifted the differential up and put it in 5th gear to let it spin and got under it to listen for noises and finding the loudest one coming from the transmission, I assumed it was that even though the noise was quiet. I did notice my shifter doing a bit of a hula though and I figured i better recheck. I had a buddy take it through the gears while I got under it and at about 40mph the howl came loud and clear from the differential. The differential it is. Anybody have suggestions on where to get a new one? Is it a good call to grab one from a salvage with the same gear ratio or is it time to upgrade? are auto-lockers expensive?

 

If you want to upgrade now is the time since it will be apart. First you have to determine what and how much yours is damaged and if it is cost efficient to fix. Gears are likely toast.

If the rest is not fixable and a good salvage diff and/or gear(s) are available I'd go that way. The $$ you save there can go to whatever upgrades you are thinking of.

 

Where does a guy go to hunt down upgrade options? I have the 4.56 gear ratio

 

Do some searches here to see what "differential upgrades" are available. I would imagine there are plenty of post on that.

If you don't find it - post up asking about the most useful upgrades for whatever you are planning to use the truck for.