I have a 98 blazer 4x4 that has a metal tapping/clunking noise. It happens when accelerating at low speeds. It sounds pretty rough when i begin to accelerate from a complete stop. It also happens in reverse as well. I believe its coming from the forward driveshaft. I felt a little play in it the other day when i was under it. any help/suggestions would be appreciated

thanks

 

Does the sound change or go away when you put the truck in 4WD?
How about on sharp turns?
How long has it been since you changed out your front differential fluid?

 

I havent checked it in 4wd yet but i will tonight. It does not change on turns. It really sounds like that forward driveshaft has something to do with. If i put it in gear, doesnt matter if its drive or reverse, and let go of the brake real fast i can really make it clunk loud (I know this clunk is not in the transmission) I can hear that it is external. And if i accelerate from a complete stop the metal wrapping noise is very noticable.

 

ok so I took it for another ride today. I noticed it doesnt really change when i put it in 4wd but I did also notice that she really struggles when turning while 4wd is engaged. But I may be wrong about it being completely external. The problem definitely lies between the forward driveshaft and the t-case. Would it help to change the fluid in my t-case? I just bought this truck as a winter beater but i dont want to break down Not really a 4wd guy so any help is much appreciated.

 

You will most defiantly want to change your fluid. If the truck is new to you then you would have no idea how old the fluid is or if it is even full.

The turning stiffness is normal while in 4WD on these trucks. The lack of change in the noise when going into 4WD points to a bad universal joint rather then a problem in the transfer case.

Something wrong in the transfer case or front half shafts will almost universally cause a change in the noises that you are hearing. A bad U-joint in the rear driveshaft will remain consistent regardless of being in 2 or 4WD.

Here is a good guide for replacing a bad universal joint.
http://www.ehow.com/how_4882887_chan...vy-blazer.html

 

i had the same think, light tapping noise. mostly at slow speed, sometimes at idle 9red lights etc) and when doing low speed turns....
then my sway bar end popped....

look at your sway bar for bad bushings etc. could also be a brake shield tapping if its loose

 

alright so i got her up on the lift today. I put it in the air and put it in drive and let it run. It seems that my rear driveshaft is way out of balance, and my tapping noise is definitely coming from the rear driveshaft. I just put new motor mounts in because the other ones were completely shot. My motor was lifting up alot. I was wondering if bad motor mounts would make my driveshaft out of balance. Or should i just do new u-joints.
Thanks