Help! Noises during acceleration from stop

[bacon612]

Hey All. I have a 1999 Denali with 192,000 miles on it. I am super happy with it and dont want to see it go.

Here's what I am noticing.

From a stop in 2wd, i hear a "yerp...yerp" noise when i accelerate. I can feel a small knock under the pedal when it happens too. Once accelerated, she runs beautifully and smooth.

What I noticed is when i engage 4HI, i dont get the noise at all from a stop.

However, when I have the wheel cut in 4HI about 3/4 in any dirrection while i drive slowly, i hear the same noise and feel that something is catching. Almost like a flat tire feels like.

I am so paniced because i dont want to loose my car.

Anyone have an idea about what my problem is?

 

[bacon612]

Here i am trying to bribe you guys by posting a picture from the summer with my truck after some off roading...


If my description of the noies that i am experiencing dont make any sense. Someone let me. Know.

Could this be an issue wit my u joints? How many are there on 4wd trucks? Or transaxle related?

 

[mygreen98]

i'd definitely check the ujoints. on your truck there are 4. 2 on the rear drive shaft and 2 on the front driveshaft. be sure to check all. post your findings.

 

[bacon612]

thanks for the quick response mygreen28.

Is it relatively easy to check the ujoints if i put the car up on jackstands? I think i recall seeing the rear ujoints when last under the car.

When i find the ujoints, what am I looking for that would be wrong with them?


Lastly, is there a DIY on replacing u joints anywhere on these trucks?

 

[mygreen98]

the joints are at the end of each driveshaft(the long tube that goes from the trans to the rear end) the look like an X with 4 round cups at each end. remove cups slowly aand check bearings. do this slowly so bearings dont fall out

 

[jbenson]

Im In Your Boat Man Got Mine Making Noise Now To. It's Really Easy To Tell If They're Bad With Out Taking Them Apart And Maybe Losing Needlebearing. Just Rock The Driveshaft Back And Forth In Park (i Use My Foot To Roll Tire Back And Foth) And See If There's Any Play In The Ujoints You Should Be Able To Notice Play In The Cap Part Of Them If They're Bad. Mine Are Noisey On Take Off To. They're Not To Bad To Change Yourself If You Have Use Of A Press Or Large Vise.

 

[bacon612]

THanks jbenson for the advise. I have a large vise in my garage and am interested in doing this myself.

I dont understand, however, how you test for the play in the driveshaft by using your foot to roll a tire. Can you explan this more?

Also is there a reccoemended brand of replacement u-joint to use? OEM the best bet or aftermarket?


I really appreciate all the help here guys. I am so happy that I just found this forum and will do my best to contribute to it where i can.

 

[jbenson]

i lay uder the truck hold drveshaft at the back u/j and with my foot on the front tire just roll the truck back and forth in parks and when it rolls back and forth you will feel the driveshaft move before the rearend moves and notice play in the u/j cap to the u/j itself. if ti's your u/j it's most likely the back one, i've never had a front one go out first. and change both front and back u/j. if you do it yourself and have problems pressing them out or in it's pretty cheap just to run shaft to a shop and have them press them in. hope that's clearer for ya.

 

[mygreen98]

agree jbenson. but ive seen some that apear to be ok, to find that the cups are full of rust, thus eliminating the "play" in the shaft. that being said, jbenson's approach is correct way to start. good luck

 

[bacon612]

So i ventured out to buy a floor jack and some jackstands today. I got home, jacked up the yukon and wheeled under it to see what I could find. It appears that the u-joints on the front and back of the drive shaft are ok. THere isnt any play in them and not really any rust.

That said. I was unable to roll the car at all because it was up on the stands. Morover, my truck is bone stock with no lift so i am unsure how i would roll it while being under it. Jbenson, is your truck raised at all?

Lastly. THere is something strange that I did notice. When up on the jackstands my rear drivers side wheel had about 20-30 degrees of play in it without connecting with the rear end and drive shaft while the rear passenger side would begin to turn the drive shaft right away when turned. Also, when facing the rear drivers side wheel and gripping it it would click a little feeling loose as though the lugs weren't tightened. My first instint was to check to see that the lugs were tight and ...phew... they were. Seems like something is loose in there. Is ANY of this normal at all? The play and the loose feel? Could this be an issue with the axel rod or rear end? I am now beginning to believe that this the noise, and the loose wheel play are all related.

Thoughts anyone?

 

[jbenson]

well if you say u/j's look good and you think there's unusual play in rearend i would say you may have bigger issues.
ya mine is lifted only 3" so sliding under might be easier with mine, sorry bout that.

 

[mygreen98]

pull off brake drums, maybe loose brake part.

 

[bacon612]

I think i will pull my driveshaft this weekend and take it to a shop to have the u-joints replaced. I see this as an inexpensive starting point. While the truck is up on stands, ill check drum too. After pulling the wheel off, does the drum just come free off the lugs?

 

[mygreen98]

slides right off, unless brake parts are broken and jamming it. or overtightened rear shoes. should come off with ease.

 

[SS5800]

My 1996 Chevy Tahoe 2 DR does the almost the same thing every once and a while. It seems that only accelerating up an incline i sometimes here a bang bang bang from the tranny possibly? Any ideas anybody?