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Grinding Noise unfounded

PEKSAV

Full Member
Joined
Sep 7, 2006
Messages
240
Location
Minneapolis, MN
Hello,
I have a 2002 AV, 231,000 miles.  For the past 18 mos. I have heard a grinding noise when driving.  I am no mechanic but it sounds like a bearing grinding. It also clunks when going from second to first gear. I don't know if those two are related.
I have been to numerous mechanics and one Chevy dealership, I either get I don't know, a guess, or like the Chevy dealership told me you will know what it is when it finally breaks.( that mechanic no longer works there)
This is what I have done to try to remedy the noise.
  Put on new tires, Replace outer and inner tie rods, idler arm, idler arm bracket, intermediate steering shaft, driver side bearing hub, front alignment, rear brakes, rear brake discs, parking brakes, rear differential fluid and transfer case fluid.
The noise gets louder as you step on the gas and quieter when you take your foot off the gas pedal.
I can't find anyone that will hoist it up a few inches  and let it run tires turning so we can figure it out.
Any help information or opinion is greatly appreciated.
Thanks
 
Know how old the driveshaft u-joints are? Does the grinding happen in reverse too?
 
With the age and mileage of your truck, I would also have a look at the u-joints.
 
I would also say the u-joints are done.
On my truck, none of the u-joints had play but I took it all apart anyway because I was chasing a noise.
One of the u-joints was totally rusted out (front driveshaft at the transfer case end I believe), and the remaining ones were not too bad, but had some brinelling going on inside the bearing cups.
I changed all of them since I had everything out. The u-joints are inexpensive, and fairly easy to replace. No reason not to do them!  (y)

CarMech1969
 
Looks like U joints are my first try. Are there any bearings associated with transfer case or differential that may be going out what are the chances of that? Thanks for all your help
 
I think you are on the right track with the u-joints, while you have the driveshaft out check for play in the pinion yoke it should not move in and out.

If it does you may have to replace  the pinion bearing
 
I didn't want to point you toward the front differential until you had a chance to look at the more common, and easier to repair options, like the u-joints.

But since you asked, my EXT has all wheel drive as opposed to your 4 wheel drive.

A big difference there, is my front differential and all of the assorted drive shafts, transfer case and u-joints are always engaged and under load with no way to disengage, unlike in a 4 wheel drive system.

A little bit of apples and oranges thing going on here.

But close enough to give you the idea.

So, in my case, when the front differential went bad, the most obvious symptom was a constant growling noise coming from the front of the truck whenever the truck was in motion.

With the 4 wheel drive system, the front differential may not be under load, but may have some rotating parts, depending on which mode you have selected, so a constant growling noise may, or may not be present at any given time.

In any truck, you are going to have some u-joints rotating and under load.

It never hurts to service your front differential and get some new fluids in there.

This will give you a chance to see if you have any metal debris on the lower drain plug. (Always start by removing the UPPER fill plug first.)

Servicing the fluid in your transfer case will also let you look at the drain plug for debris.

But I would focus on the u-joints and go from there.

Tearing down and rebuilding the transfer case and front differential can begin to get a little pricey, especially if it is not needed.
 
Thanks, I will start with u joints.  I just replaced my rear diff. cover due to it rusted through and weeping fluid.  The magnet in the cover was caked with filings. I will be checking the yokes too.
 
Greaseable are pretty good, just make sure when you install them the part where the fitting is are on the compressed side.
 
OK I'm terrible at diagrams so here is my best shot at it

The compress side is compressing the Tension side it stretching

It also depends on what type ujoint you get some of them have the grease fitting in the center


normal_ujoint.png


normal_ujoint1.GIF

 
  Use YouTube. Mark your driveline and yokes.
They need to be assembled the same way they were dissembled.
This keeps in time and  will help keep things balanced.
 
Just had it checked today, turns out front and rear diffs. are shot.  They put it up on a lift and ran it so I can hear.  Sure enough.  If I decide to repair, $2000-$3100 depending on exactly what's wrong, I will have them replace the all u joints too, why not
Thanks for all your help and info
 
PEKSAV said:
Just had it checked today, turns out front and rear diffs. are shot.

Sorry to hear the bad news.
There seems to be an issue with Chevy diffs. From what I've heard, the pinion bearings like to go out on them.
Did they tell you what failed in the diffs?
Curious to know.

CarMech1969
 
That does bite I kind of thought that is what it was, that or the transfer case.
 
Turns out both diffs were shot.  Had both diffs replaced, also new u joints, balanced drive shafts.  One month later tranny went out.  Replaced that too.  Newer engine, new front and rear diffs., new u joints, balanced shafts, new tranny, all that's left is to get a new transfer case.  Hope it survives the winter.
 
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