High pitched screech

[Prairie Dog]

I've got an odd screech that seems to come from the middle of the underside of the truck. It is NOT the brakes - which have been changed twice and gone through thoroughly. Brake input makes very little change to the pitch.
The sound comes when coasting under compression or neutral, clutch in or out. It has gotten louder lately and often sounds like a loud whistle. The sound goes away immediately under the slightest throttle input. The sound is also there under the same conditions with the eng off.
Today I removed the rear drive shaft (which is a low mileage 1 pc Dodge unit) and drove it and the the noise was gone. The DS is in perfect condition and the joints are tight and buttery smooth.
Since the rear end is under the same loading conditions as when the shaft was in, I cant see it being the problem. Or can it? The rear end was gone through 16K ago. (ugly story)
Fluid levels are good and no metal is evident in the transfer case or diff.
Can a transfer case make a noise like that?
Any and all idea's are welcome!

Thanks!
Scott

 

[Bob4x4]

Chassis ears can be a big help.http://www.tooltopia.com/steelman-6...ntid=STE6600&gclid=COT4i6fW7dECFQ9EfgodsLgPbQ

 

[ScottLewis]

Off the top I would suspect the ball and spring of the Carden joint. Years ago the one on my old Bronco made a sound like you described and that's what it turned out to be.

 

[Prairie Dog]

Off the top I would suspect the ball and spring of the Carden joint. Years ago the one on my old Bronco made a sound like you described and that's what it turned out to be.

Thanks Dan, that was the first thing I suspected of the front DS but removing that shaft made no difference and the back is a 1 pc.

 

[ranger 393]

I would suspect a dry universal joint. May move freely when shaft is out by hand with no pressure on it, but with pressure on iy may be causing it to squeal.

 

[Prairie Dog]

I would suspect a dry universal joint. May move freely when shaft is out by hand with no pressure on it, but with pressure on iy may be causing it to squeal.

That was about it.
A long time mechanic buddy came over last night just to check things out. While it felt good to me, he could feel a slight tightness on one side of the joint. A light tap on each side of the yoke and now it's silent. Apparently the caps were installed too tight by Dodge.
Even though all seems to be well, I have a couple of thoughts...
Is the UJ damaged inside?
My buddy smacked the yoke and loosened the UJ which is glued in (no retainer clip). Is the glue compromised now?
Maybe I should try and add the clips?

 

[ranger 393]

That was about it.
A long time mechanic buddy came over last night just to check things out. While it felt good to me, he could feel a slight tightness on one side of the joint. A light tap on each side of the yoke and now it's silent. Apparently the caps were installed too tight by Dodge.
Even though all seems to be well, I have a couple of thoughts...
Is the UJ damaged inside?
My buddy smacked the yoke and loosened the UJ which is glued in (no retainer clip). Is the glue compromised now?
Maybe I should try and add the clips?

I would doubt the glue was damaged,you have to heat it with a torch to get that stuff out then the caps will fall out. I would guess that they are dry and the needle bearings is what is making the noise. I would just replace the ujoints for peace of mind. The new joints will come with clips.

 

[Prairie Dog]

I would doubt the glue was damaged,you have to heat it with a torch to get that stuff out then the caps will fall out. I would guess that they are dry and the needle bearings is what is making the noise. I would just replace the ujoints for peace of mind. The new joints will come with clips.

Done!
Called a local drive line place and they told me not to drive it after disturbing the glue. So I just pulled it and had them put a new joint in. Since the ears are aluminum I didn't want to fight with the glue like I've done with iron stuff in the past - well worth the $20.

Thanks to all who responded.

Scott