Squeal/Jingle/Metal on Metal Symphony

[JerrySab]

Hi all!

Back again.

I'm trying to diagnose a semi-persistent sound that I'm pretty sure is not coming from transmission. It mainly turns up once truck is warmed up.. worse when I've been overdoing it in stop/go local driving. The sound occurs after acceleration, as I'm letting off the gas and coasting. At times its a jingling sound. Others its a metal/metal squeal, almost like a dolphin. It seems to not be present when under load. I assumed transmission (auto A4LD w OD) problem but a local mechanic drove around with me and wouldn't confirm transmission, as shifting/acceleration is pretty smooth and direct, no slips.. and instead suggested I check u joints and prop shaft or rear dif. Quick inspection, I did notice the output shaft seal is leaking and spraying fluid onto the underside of the bed. More of a seep than a full leak.. could be culprit? Any advice on what to look for in terms of failure points would be super welcome.

Thank you!

 

[Dirtman]

First thing to check is the heat shields on the catalytic converters.

 

[ecgreen]

First thing to check is the heat shields on the catalytic converters.

This. Get under there and rattle stuff around. I had a similiar rattle at 2500RPMS and it was the shield between the tranny nd engine

 

[JerrySab]

aight gonna bang on some stuff brb

 

[JerrySab]

Sadly, the shielding welds are all holding and not wiggly. I didn't see any other smoking-guns, as I thought it might also be the e brake cable rattling around. Pretty sure it's coming from U joints? But I haven't had my hands on those yet so going to research what a failing joint would look like/act like when vehicle isn't running. Any thoughts, I'm all ears.

Thanks!

 

[JerrySab]

unless this crusty guy is culprit?

 

[Curious Hound]

View attachment 65307
unless this crusty guy is culprit?

Will be soon if it isn't now. There could be loose parts inside the muffler or catalytic converter. But, really. You might just have to get under there and wiggle things and bang on stuff. It's a legitimate troubleshooting method.

 

[JerrySab]

Yeah I'm thinking it's a family of problems along the driveshaft. Will pull the thing and see. YAAAAY.

 

[JerrySab]

IT TOTALLY IS THAT PEICE OF SH*T.

The metal washer on the back that's supposed to be adhered to the assembly to prevent dirt from getting in? Completely separated. Going hog-wild anytime driveshaft moves. Even just flicking it against the bearings spiked my stress levels. They seem to be pretty affordable parts, would anyone have any tips re: replacement process (since I'm here and demanding attention)? Is it best to pull the entire shaft? Or is it better/possible to just disengage U joint nearest differential and slide hanger bearing off that way?

 

[ecgreen]

If its the original shaft, I would take it out and replace everything I could.

 

[Eddo Rogue]

swap to a one piece driveshaft if you can. I'm glad I did.

 

[JerrySab]

swap to a one piece driveshaft if you can. I'm glad I did.

what's that now??? I've not heard of this witchcraft..

 

[JerrySab]

Is it best to yank one from newer models? Or could you recommend a 3rd party option??

 

[Dirtman]

You can get a 1 piece from a 98+. Don't know if anyone actually makes one but you can have one made. Try Tom woods custom driveshafts. Way more expensive than a junkyard driveshaft obviously...

 

[Eddo Rogue]

I found mine on ebay. it was like a hundred something bucks shipped. I was looking at the aluminum ones, but they were hard to find and way more expensive, so I got a steel one. Swapped in some brand new Spicer u joints while at it. The hardest part was removing the support bearing crossmember. Got the rivets out but still wouldn't budge, so I ended up slicing it out reluctantly. Anyways it worked out awesome. Eliminated my vibration issue.