So this just started a few days ago. Whenever I speed up or upshift gears (manual transmission) during acceleration I hear and feel a "clunk". Seems like it is coming from right underneath me but I am not sure. I read something in the PSD forums about a slip yoke problem that is inherent in these trucks. Does this problem go back to the IDI as well? Anyone else had this same thing happen?

 

Could be u joints, hanger bearing, tranny mounts, or even clutch issues.

 

What year model is it. Does it clunk when you kill the engine.

 

1994 n/a idi. Manual 5 speed. I can leave it in gear, slow down a little then speed up and it does it. Only when speeding up tho. Never does it when I am slowing down, at least not audibly.

 

no clunk when I kill the engine. No clunk when idling sitting still. No clunk when slowing down. Only when speeding up. Note that when you shift gears that you will slow down a little when you do this so when it goes into the next gear and starts speeding up then I hear the clunk. If I am VERY careful when I releas the clutch so as not to change speed in any way then I can make the clunk go away. I don't think this is clutch or transmission related. Maybe the mounts but if it were the mounts wouldn't i hear the clunk when I was slowing down as well as speeding up?

 

I can sit idle and shift gears all day long, press clutch rev engine and no clunk. I have to be moving.

 

U.joint, carrier bearing, slip yoke,or slack in the ring and pinion.

With your motor dead and tranny in nuetral, you should be able to find slack somewhere in the driveline.

Not as common but can be a loose or damaged spring or mount on the rearend.

 

It really feels like it is somewhere after the tranny. I had some drive shaft work done last year and they did a shoddy job (as ussual). I had to take it to another place to get the first fix fixed. I guess this is just part of that mess...

 

just get under the truck with it off,and in gear,and try turning the drive shaft back and forth,you'll see the problem hopefully in just a couple seconds.most often its just the U-joints.so look at them closely first.
you won't know until you look.
cheap and easy to replace.
you could have had this fixed probably yourself before lunch and less than 20 bucks.

 

If you want to find the slack you need to leave it out of gear.

 

Yup, set the parking brake on and put the trans in neutral - if she's in gear then there will likely be load on the driveline and you won't be able to feel the slack in the U-joint or wherever else it may be.