Clunk on acceleration
 

I have this clunk under acceleration that isn't always there. Some times theres a clunk when accelerating from a stand still but most of the time it doesn't do it.


Any idea what it could be?


I checked and greased the ujoints on the drive shaft when I did the exhaust fix this previous weekend and the driveshaft had no play up and down or twisting the shaft back and forth.


I know the front bushings need to be replaced as well as the upper and lower balljoints.


But every time I look at the truck I cant find anything that is loose that could be the clunk so if anyone has any recommendations on what I could check I would like to hear feed back on this.

Motor mounts?

This is easier with another person to help... park it, make sure it won't hit anything if something bad happens...

Open the hood, start the engine; step on the brake, put it in gear (if auto) or depress the clutch and put it in gear as if you're ready to go from a stop light...

Step on the gas a fair amount while you watch the engine from the hood/cowl junction, or have a helper watch... see if it raises up off of a broken motor mount/clunks down back onto it as you release the gas (assuming auto, stick should be pretty obvious).

I can check it again just to be sure but I checked them once before and the mounts were good.

Tranny mount?

When I was under the truck the transmission mount did look a little strange not exactly sure how I would test it other than using a prybar to see if theres any movement.


I need to say there is no clunk when you switch from reverse to drive or shift into gear. There is also no clunk when you hold the brake and load the engine up I have done this numerous times when I was trying to resolve the rough idle and I was trying to verify if it was a misfire or not.

my guess is the radious arm bushings get those done and the clunk will be done as well

I was wondering about what Bert is saying. However, mine are bad on my 96, but the only time it clunks is when I am off road and the terrain is very uneven. Whenever the radius arm has to reach way down to stay in contact with the road it clunks. Like when I drive into a ditch.

Oh, that is easy... avoid ditches!!! }>

Not the radius arm bushings as I thought that's what it was years ago and when I put new inner and outter tie rod ends on the truck I installed new polyurethane radius arm bushings. I will how ever bring my large prybar home from work and see if the transmission mount is bad. It looked bad but it doesn't always do the clunk and whats odd is it only does it under acceleration from a stand still if it does do it. Wont do it in gear with your foot on the brake and hitting the throttle loading the engine up.

<p>If it's not the motor or transmission mounts, my next guess would be suspension o TTB axle-related, e.g. ball joints and/or TTB pivot bushing.</p>

I agree with Chris. I have been chasing a similar light clunk when accelerating from stop or very slow speeds. It has been looked at by a front-end specialist and nothing could be found. It does seem to either go away or lessen in intensity when it rains heavily, so I think it is something moving where the springs mount or similar, which when wet, does not make as much noise.

still could be U joints. had a car that would give the occasional 'clunk'. took the driveshaft off, joints felt tight.
Bought new joints anyway, taking it apart, one cap had about half the bearings missing.

I might pull the axle off and check the U joints maybe just replace them anyways. I do know I need ball joints as on cold days turning the wheel results in a popping. I just have been putting this off for a long time. Maybe its the ball joints allowing the front spindle to shift making the popping.

U joints can be elusive. Besides shaking them and prying on them for signs of movement try to visually inspect them and see if any of the caps are shiny around the top edges where they are retained in the yokes. Sometimes the caps spin and cause this. Another test would be to crawl under after you have driven a few miles and see if any of them are hot to the touch. If they are hot then they are bad.


Do you think there is too much backlash in the differential? That makes a clunk.

I thought of the backlash but every diff I have seen that had excessive back lash would make a clunk when you shift into gear from reverse to drive. This doesn't clunk when shifting between drive and reverse.