96 blazer clunk noise...

[peacestamp]

So I have a 96 blazer with a bad clunking/grinding noise, but its only when the truck is warmed up, and when you accelerate. I looked at the muffler and there is a very small hole I thought maybe it could be that but I dont see how it could make the noise. It doesnt do it on idle unless the truck is warmed up, but it always does it when I accelerate, and it sounds like its coming from the undercatrriage, any help or suggestions would be great

[blazes9395]

A clunking noise can be a bad U-joint(s), especailly when you are accelerating. A really bad u-joint will grind too...

[CanukGMC]

Double on the ujoints. It's the easiest to check, cheapest to change. Chock the front and rear wheels so the truck will NOT move, set the ebrake if reliable too, put the tranny in N and go underneath the truck. Grab the driveshaft running to the rear axle and pull on it up and down, left and right, etc. It should have zero play. If it clunks around then the needle bearings are done and the ujoint(s) are finished. Another symptom of a bad driveshaft ujoint is a vibration on the highway.

The next thing to check is engine mounts, tranny mounts, etc. If one of those are blown they can clunk under accleration.

[peacestamp]

Thanks alot guys... I went and had it checked out, turns out its a bad catalytic converter but I probably do have to change the ujoints as well, because its pretty old