Signs & Symptoms of U-Joints Going Bad


yourmusicmuse.com
03-28-2012, 08:46 AM
Hello automotive forum users!

I am trying to diagnose my 1999 Chevy Silverado 1500 that is 4WD with extended cab. It has a V8 4.8 liter motor, and around 134000 miles on original automatic transmission and engine. I think it's got a bad u-joint or two, but just not sure.

Truck symptoms are:
1. "Bird chirping" noise when 1st accelerating 0-30 mph. After 30mph, I cannot hear the noise. That could be because it goes away or because I'm going to fast. Don't know. :)
2. "Clunk" sound when I put truck in reverse, but does not happen when put in drive.
3. Some vibrations when on highway in steering wheel, but I'm not sure if this is related to the u-joint issue. Could be out of alignment, etc. Bought the truck 3 months ago, used, and have not had it aligned myself.

Signs are:
1. I climbed under the truck, and looked at u-joints. They appear to be rusty around the outside.

Now, I did ride in the bed of the truck, while someone drove at the lower mph. I was able to hear the noise, and I pinpointed it the center of the truck. When I looked in between the truck cab and bed crack, I could see the drive shaft spinning, and I felt the noise was coming from the direction.

Does the signs and symptoms point to bad u-joints? Or something else?

P.s. I'm female, and I do work on my own vehicles, but I'm wondering if this would be something I should let a shop tackle? I've never done u-joints or anything with a drive shaft before. Other than changing out the CV joints on my Olds Alero by myself.

Thanks for all your help and guidance, in advance! :)

j cAT
03-28-2012, 10:19 AM
to check U joints the rear wheels [both ] need be off the ground. then with the transmission in neutral rotate the drive shafts and check for any play in the joints. no load is required to check these joints. rust is normal.any lube weeping at the joints is a possibler indicator of joint wear.

this is not full time 4WD. DO NOT OPERATE THIS VEHICLE ON DRY SOLID PAVEMENT IN ANY 4WD SELECTION AND THIS INCLUDES AUTO 4WD.

ALL TIRES MUST BE THE SAME SIZE AND WEAR.

tires must be rotated every 10-15,ooomi. if the tires are at various wear /tread depth the 4 wd will get worn out.

get the tires speed balanced and have them use stick on wieghts not HAMMER ON SIDE WEIGHTS.

have the vehicle height adjusted if it has dropped. adjusting the torsion bars is not very difficult.

I do not recommend you replace these U joints. this is a job for a person that is experienced in mechanical repairs.

since you just purchased this things to do. replace all the drive train fluids. use the dexronVI fluid for the transmission NOT DEXRON III.
FRONT/REAR gear boxes. transfercase fluid.

777stickman
03-28-2012, 10:24 AM
Welcome to AF: With the tranny in neutral and the park brake set, check the u-joints for any up & down or side to side movement. None allowed.

yourmusicmuse.com
03-28-2012, 10:36 AM
Do I have to have the vehicle on jacks to check it by putting it in neutral with the parking brake fully engaged?

j cAT
03-28-2012, 12:08 PM
Do I have to have the vehicle on jacks to check it by putting it in neutral with the parking brake fully engaged?

the parking brake set will mess you up on checking this. use blocking on the front wheels both sides to prevent vehicle moving.

do all this on level ground.

the reason you must have both rear wheels off the ground is, because when you start rotating the drive shaft the rear diff will automanticly lock and both wheels will be rotating and locked together.

MT-2500
03-28-2012, 04:27 PM
Besides checking for sideways or up and down movement if a center carrier bearing or double joint set up check center carrier bearing and double joint center ball and driveshaft slip joint splines.
Also drive vechica about 5 miles and then feel u joints caps.
If one is hotter than others or burns your pinkie it is bad.

yourmusicmuse.com
04-03-2012, 08:29 PM
Hey all. So, my mechanic calls me to tell me he's inspected the u-joints and they don't appear to be the problem. There is no movement, he says.
He did say my transfer case is leaking....would that cause the above symptoms?

Thanks.

j cAT
04-04-2012, 07:48 AM
Hey all. So, my mechanic calls me to tell me he's inspected the u-joints and they don't appear to be the problem. There is no movement, he says.
He did say my transfer case is leaking....would that cause the above symptoms?

Thanks.

SOME OF THESE TRANSFER CASES HAVE A LEAK . this is from a part that wears into the case. I would bring to a transmission shop that is familiar with this problem. call and ask if they have repaired this gm defect. If you search internet there is a utube video about this .

where exactly is the leak ? what is the fluid level ? what color is the fluid ?

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