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Username Post: howling noise from drivetrain        (Topic#217068)
Posts: 6

Loc: midwest
Reg: 11-06-04
05-16-09 03:43 PM - Post#1698824    

Have a howling noise coming from the drivetrain. I have ruled out the engine when put it in neutral going down a hill and the noise was still there ! It starts at 48 mph and is there past 70 mph. I crawled under the truck this morning and pushed and pulled on the driveshaft. I couldn't feel any play that would indicate a bad u joint. I did get the bearing block on the split drive shaft to move around a little, but don't know if that is normal. I rotated the driveshaft with the rear wheels raised and got some play from the ring and pinon, but again, don't know if that is excessive or normal. Couldn't find any grease zerks other than the one section of the driveshaft so I greased it. This all started about two weeks ago. This is a 2000 S-10 extended cab with 4.3 auto and 2wd. Truck has 196,000 highway miles on it. any suggestions as I don't want something to come apart going down the interstate. Thanks


LMC Trucks
Senior Chevytalk Moderator
Posts: 22346
Loc: Austin, TX 78748
Reg: 05-09-00
05-16-09 04:03 PM - Post#1698833    
    In response to malibu69

With that many miles, I would change out the u-joints and the carrier bearing. Have someone stand next to the truck. Shift the tranny into R and D. Do you hear a clunk? Sometimes it's hard to find bad u-joints by yourself. A little play in the yoke and rear end is okay. They are designed that way.

Check the rear differential for leaks. Low oil will cause the rearend to make a howling noise. Once the rear end starts to howl for low oil, it wont' stop even if you fill it back up. Add some oil anyway. I would change it if has not been changed.
'83 Silverardo XST - ZZ4 powered
'96 GMC Jimmy LS Ret. @236651 miles

Posts: 6

Loc: midwest
Reg: 11-06-04
05-16-09 09:55 PM - Post#1698993    
    In response to gchemist

Glad you mentioned the rear end oil. Forgot to post that I pulled the rear end plug and it was a little low. I filled it up with rear end oil and took it on a test drive, but still howling. Next opportunity I get will change out rear end oil. It hasn't been changed since I bought it in 2002. I will have someone help me listen for a clunk when in drive and reverse. If it is differential that is making the noise any suggestions on how to tone down the howling ? I had hear of people using Lucus oil additives in manual transmissions with good results. Thanks

"14th Year" Silver Supporting Member
Posts: 15612
Age: 81
Loc: Montana
Reg: 03-12-02
05-17-09 07:29 AM - Post#1699113    
    In response to malibu69

My 91 S-10 Blazer blew a differential seal, parking it on gravel I did not notice the leak. I did find it when I was under the unit doing other work. Rear end was not dry but low, about 10,000 miles later had to replace both carrier bearing, as there was a constant howl coming from the rear.


Edited by 2blu52 on 05-17-09 07:29 AM. Reason for edit: No reason given.

Posts: 71

Loc: mn
Reg: 12-22-05
05-19-09 05:18 AM - Post#1700536    
    In response to 2blu52

I would pull the diff cover and check for debris ,
My brothers astro had a howl and it was the pinion bearing , new pinion and diff bearings and peace and quiet . good luck .

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