Clunking and banging on acceleration

[donsanders97]

Have an 83 C20. 350, Muncie 4 speed.

Driving in first when I accelerate, there is a hell of a clunking noise. I thought for sure it was U-joints. Pulled the drive shaft and replaced the U-joints and since I had it out I replaced the carrier bearing.

Put the drive shaft back in and took it for a spin, same clunking and metal banging on acceleration.

I’m thinking differential but wanted to check the collective wisdom, before getting into something far more complex.

Thanks for all your help.

 

[Snoots]

My money's on the diff.

 

[Radiohead]

Or busted motor/trans mount.

Kinda hard to tell when you can't hear it

 

[donsanders97]

Or busted motor/trans mount.

Kinda hard to tell when you can't hear it

Nice I’ll check that first .

 

[wanderinthru]

Or busted motor/trans mount.

Kinda hard to tell when you can't hear it

This. The few diffs I've had go bad only clank and bang when things equal out. Is the pinion seal leaking? Alot of slack when you changed the u joints?

 

[89Suburban]

So it's in first gear only? Not in any other gears or reverse? The usual weak point of a diff is the spider gears. If they are on their way out you would know it. If you turn while driving it may change the sound and feel as those gears change position to compensate.

 

[donsanders97]

So it's in first gear only? Not in any other gears or reverse? The usual weak point of a diff is the spider gears. If they are on their way out you would know it. If you turn while driving it may change the sound and feel as those gears change position to compensate.

Haven’t wanted to accelerate enough to change gears for all the calamity and clunking I hear on acceleration.

If I don’t hit the gas and keep it in first and run at idle I don’t get the clunk/clang nor does it happen while turning.

So in reading all these reply’s it may be a busted mount. Keeping my fingers crossed when I roll underneath

 

[89Suburban]

Haven’t wanted to accelerate enough to change gears for all the calamity and clunking I hear on acceleration.

If I don’t hit the gas and keep it in first and run at idle I don’t get the clunk/clang nor does it happen while turning.

So in reading all these reply’s it may be a busted mount. Keeping my fingers crossed when I roll underneath

Need to get it up in the air and spin some wheels and axles and stuff. Hopefully it's not something major.

 

[skysurfer]

You'll need to check the motor mounts beyond obvious signs of breakage. I had a situation where the rubber inside the clamshells degraded and allowed the motor to torque-over far enough for the driveline to make contact with the crossmember.

 

[donsanders97]

So just as some of you suspected we had a loose transmission mount. Hooray!!! Or so I thought. Took it for a test drive and it got worse. The sound of gears grinding singing to me.

Have a video of it and no matter what gear I get in….when I let out on the clutch, grinding gears greet me. Even reverse.

Now I fear the differential is just fine but the transmission may be shot.

 

[SirRobyn0]

So just as some of you suspected we had a loose transmission mount. Hooray!!! Or so I thought. Took it for a test drive and it got worse. The sound of gears grinding singing to me.

Have a video of it and no matter what gear I get in….when I let out on the clutch, grinding gears greet me. Even reverse.

Now I fear the differential is just fine but the transmission may be shot.

Well you can pop the diff cover check the fluid and gears for obvious damage. If there was some way you could get an assistant to help you listen to see if it's coming from under you or behind you that would be helpful to narrow it down some.

 

[Ricko1966]

Well you can pop the diff cover check the fluid and gears for obvious damage. If there was some way you could get an assistant to help you listen to see if it's coming from under you or behind you that would be helpful to narrow it down some.

Or just make sure it has gear oil in it.

 

[donsanders97]

Well you can pop the diff cover check the fluid and gears for obvious damage. If there was some way you could get an assistant to help you listen to see if it's coming from under you or behind you that would be helpful to narrow it down some.

I had an assistant. It’s coming from the transmission and it sounds like when someone is grinding the gears except it’s in gear and happens when you let the clutch out

 

[SirRobyn0]

Or just make sure it has gear oil in it.

Agreed I just thought popping the cover off the diff to do a quick inspect, would tell him if that's the problem. Looks like he's pretty sure it's coming out of the transmission though.

 

[donsanders97]

Agreed I just thought popping the cover off the diff to do a quick inspect, would tell him if that's the problem. Looks like he's pretty sure it's coming out of the transmission though.

Gonna check oil levels on both tomorrow. But the new sounds are scaring me for sure.

May also disconnect the drive shaft and put it in gear. That will help eliminate sources of the grinding.