Clunking noise when clutch is depressed/released (joint, brake, truck)

[Deez Nuttz]

In addition to the recent clutch release bearing issue on my 91 S-10 4X4, I've also learned sometimes pushing in thew clutch to shift I get a 'clunk' sound from underneath and sometimes when i release the clutch I get the same noise. It seems to be more common in 2nd and 4th gear letting the clutch out but I think I've also heard it happen in 3rd. It only happens in 1st if I let off the gas pedal then push in the clutch.


I've read this is attributed to U joints, but I tried grabbing the yokes with one hand and turning the drive shaft with the other but they don't move against each other. I also tried the same thing on the front drive shaft which of course spins freely until 4WD. My drive shaft is a 1 piece.

What/where else should I check? Thanks.

[M3 Mitch]

Sometimes noisy U-joints are not loose enough to feel it with your hands. Try this: Drive awhile, then park where you can get under the truck, secure it so it won't roll for sure, then just feel of the u-joints with your hand, they should be cool to barely warm. A bad u-joint will generally be pretty warm, warmer than the rest of them.

Did you put in new transmission mounts with the transola work?

Check that all the mounting bolts are good and snug.

This kind of noise can be a PITA to track down.

[Deez Nuttz]

I didn't do the work, I'll ask my mechanic.

[bmd69]

Throughout bearing?

[Deez Nuttz]

Per the tech that did the work, the clutch disc, pressure plate, throw out bearing and pilot bearing were all replaced.

[M3 Mitch]

When you have some time, try to figure out what excatly you can do that causes the clunk. Try working the clutch with the engine off. It can be very useful to have someone else work the clutch while you watch the linkage, make sure everything that needs to be moving is moving without interfering with anything, make sure stuff that should not be moving is staying still.

You might try (use common sense and stay safe if you decide to to this!) laying on the garage floor under the truck while a friend pushes the truck back and forth a little, with the engine off and the truck in gear, e-brake off...

At the end of the day, this is a GM truck, and a certain amount of clunking and rattling is normal. Without hearing it I can't offer an opinion on if what you are hearing is normal or not.

[Deez Nuttz]

The clunking usually happens when pushing in the clutch or letting out the clutch.

For instance, I can be sitting still, trans in 1, let slowly off the clutch...a little rattle....push in clutch *clunk*...shift...let off...*clunk*....

There's no certain gear it does it in....it can do it in 2,3 or 4....and it can be letting off or pushing in....it's not consistent each time.

I've owned a few GM trucks, never had one with a gear box/clutch that sounded like this. I did learn that idling in neutral when cold there's not much noise but idling in neutral when warmed up sounds like rocks thrown around inside the bell housing/gear box.