Squeel in Reverse?

[C6H12O6]

Truck drives fine, no shakes, vibrations, etc. in forward gears. If I put it in reverse, say to back out of a parking spot, I hear a pretty loud squeeling noise that sounds like it is coming from the transmission or driveline area under the truck. It isn't a consistent noise ~ it sounds as if it is metal on metal screaching as something turns and gets louder as it turns past a certain spot. Brakes don't seem to change the sound, nor does RPM. It gets faster as the truck reverses faster, but independent of RPM.

U-joints finally going? Driveline issue? Tranny runs/shifts as smoothly as it has since I bought the rig and the noise sounds pretty un-muffled ~ not as if it is something rubbing inside the tranny. It almost sounds like a fork being rubbed on a china plate. Very annoying.

 

[stevek]

I just recently tracked down the same noise on our 93. Turned out one of the exhuast hangers had rusted through and for some reason would move only when the truck was in reverse.

 

[C6H12O6]

Hmmmm...

I just noticed that one of the brackets on my Borla exhaust had broken. I wonder if that is what's causing the noise. I'm going to try and get that welded up next week. Hopefully that does it.

Any other possibilities?

 

[C6H12O6]

Update

Ok, I climbed under tonight and have been paying attention to the noise a bit more this afternoon. It is definitely getting worse. I now hear it in forward as well, but only at really low speeds. It isn't a solid, consistent squeel, but more of a finger nails on a chalkboard background noise with a louder, rhythmic squeek, squeek, squeek, squeek as if something is rubbing worse as it rotates past a certain spot.

It is still louder in reverse, and the noise is getting a bit more of a pattern to it. It really sounds as if it is metal on metal at one particular spot in the driveline rotation, but I can't see anything amiss under the truck. The u-joints look fine (although they are a bit worn at 180K) and nothing seems to be rubbing anywhere.

The only thing I noticed was that the rear shaft is not in line, meaning the u-joints are not in phase. I pulled the shaft to clean and grease the slip yoke a few months ago and must have put it back together one notch off. I'm guessing this is bad. No bad vibrations. No noise at speed that I can hear, no increasing grind/squeel as RPMs come up. I can't tell if that's it or not. I should probably fix it anyway, but I need to just order new joints and do it right if I pull the shaft again.

Also, I checked the exhaust. I don't think that's it. The mount is broken, but that just doesn't make the same kind of sound. I can hear it rattling, but that just isn't the same noise.

Anybody else have any suggestions?

 

[GeoRoss]

Every so often when I start the truck in the morning, I get a 'whine' while in reverse. I have justed assumed that it was the PS pump. It only happens when the engine is cold/first start in the morning.

I haven't noticed it since flushing the PS fluid, but it hasn't been very cold lately.

Ross

 

[C6H12O6]

yeah, this isn't that. I had a similar noise before the PS fluid flush as well. I almost thought the noise was just more apparent now that I'm fixing other things, but it is clearly getting worse. I could even hear it on the freeway this afternoon.

The noise really sounds like some sort of bearing going out. The noise is clearly related to some spinning component somewhere. It seems to be worse when in gear. A couple times, I could hear the noise in reverse, then put it in neutral and just coasted back and the noise almost went away. Same thing in drive. I'm thinking maybe the bearing needs to be under a load to make noise. It definitely sounds as though the speed of the squeel's repetition is similar to the spin of the driveline.

Without a FSM to flip through, is there a bearing at the rear of the transmission or TC that is likely wearing out? I'm still hoping it is a u-joint. I guess CDan won't have to wait until payday.

 

[eurorom]

Sounds like your Transfer case needs to be check, have you check the fluid on your transfer case?

 

[C6H12O6]

Don't say that.


Please send me $40 u-joint vibes.

I'll change the tcase fluid tomorrow morning. I just replaced the diff fluid a few weeks ago with new M1. I bought enough for the tcase, but I spilled some knocking a bottle over and didn't get to it after that.

 

[-Spike-]

IMHO, sounds like a bearing. Internet diagnosis has been wrong before though. I can't imagine bad u-joints causing a squeel, but if you were a spline off I could see the vibration from the driveline being out of balance wreaking havok on your t-case output bearing/bushing/whatever's in there, or the pinion bearing. If you didn't mark your driveline before you pulled the slipyoke apart, it could be way off, like 190 degrees or something, making for balance issues.

-Spike

 

[C6H12O6]

I marked it, but I used a sharpie and it came off when I cleaned it. Moron.

It looks like the front and back of the rear shaft are one spline off. The weird thing is there is no bad vibrations that I can feel. It doesn't feel any worse/different than before. I would think if anything was bad enough to cause damage, I would have felt it before now and it wouldn't have taken 3000 miles to rear its ugly head. Maybe.

I'll go look at the FSM i have on the computer. Maybe it will give some insight. Any guesses what the TC output bearing costs to replace? Anything I can try to test it? I may go out somewhere and put into low range to see if the speed/pitch/volume of the sound is any different.

Thanks for your help. All input is gravely appreciated.

 

[dfmorse]

Might want to check the brake pads. Could be the squeel tabs.

...

 

[C6H12O6]

yeah, I thought maybe, but they were just replaced a few thousand miles ago and the noise doesn't change when the brakes are applied, nor with the parking brake. I'm stumped. I might have the wife ease the truck back and forth while I lay under it. Wait, that's bad. Maybe I'll lay next to it and see if I can pinpoint where the noise is coming from.

Keep 'em coming. Thanks for all the help.

 

[eurorom]

Let's check your transfer case, put in low range apply the breaks try to bring your RPM to around 2.5k the noise should come up at around that range! Just try, also check your fluid.

 

[CJF]

Easy enough to pull the driveshafts and check the u-joints; I don't see that you've done that?

Curtis

 

[seabeecruiser]

I had a small rock get trapped in the rear brakes and would squeal only when in reverse. Drove me nuts. Took me a couple of days to find it, but that fixed the problem.

 

[C6H12O6]

I haven't pulled the shafts yet, but I did climb under there last night with the wife slowly backing the truck...

The noise is definitely coming from the rear joint on the front shaft. Now, whether that noise is a front output bearing in the TC or the u-joint, I guess we'll find out as soon as I can get new u-joints in there. I pumped several squirts of grease into the u-joint, and it seemed to quiet it down a very little bit, but that could just be wishful thinking on my part.

I still can't seem to get any clunking or movement on the driveshaft, which I would expect to see if things were this FUBAR inside. I did notice that the metal ring on the front of the TC had a very light metal ringing tone when tapped. If there were a rock wedged up inside there between it and something else, I could totally see that being the cause. I'm gonna call Dan in the am and order some stuff.

Wish me luck!

 

[CJF]

The noise is definitely coming from the rear joint on the front shaft. Now, whether that noise is a front output bearing in the TC or the u-joint, I guess we'll find out as soon as I can get new u-joints in there.

Pull the shaft before you order anything. A worn u-joint is usually pretty obvious (notchy, or freeplay, or...) just from articulating it by hand with the driveshaft removed.

Curtis

 

[C6H12O6]

I would, but if it is bad, I'm not going to put the old one back in and I need wheels. Downtime sucks on the DD. Judging by the shape of the rears when I pulled the rear shaft, they will need to be replaced too, so I think it's getting new u-joints regardless of whether that is the sole cause of the noise.

 

[C6H12O6]

Just a quick update to close this thread down:

I pulled the drive shafts last night. The rear joint on the front shaft is toast. You can clearly hear the squeeking noise as you articulate the joint and it is so rough, I'm amazed it didn't have more of a clunk to it.

Both shafts are getting new OEM joints and a fresh balancing job as we speak.

 

[CreeperSleeper]

Just a quick update to close this thread down:

I pulled the drive shafts last night. The rear joint on the front shaft is toast. You can clearly hear the squeeking noise as you articulate the joint and it is so rough, I'm amazed it didn't have more of a clunk to it.

Both shafts are getting new OEM joints and a fresh balancing job as we speak.

I'm glad, Steve. It looks like your T/C rebuild has been put off for another couple of weeks!