[martinv]

My 1992 grand caravan vibrates on acceleration. It is most noticeable from 40-70mph. It only occurs when accelerating or when there is a load on the engine (going uphill).

I suspect it's not an alignment/balance issue becuase it only occurs on acceleration. I have recently replace the Drive shafts and swaybar bushings.

Someone suggested it could be spark plugs, wires or the coil pack. I will probably do the plugs and wires first as they are old anyway.

any other ideas?

Thanks,
Martin

 

[Dodgevanman]

Check the motor mounts..particularly the ones on the transmission. A busted mount can cause a vibration.

 

[martinv]

Update:

I replaced the plugs and wires. This did not stop the problem.

I did check the engine and transmission mounts. None were broken. These are the original mounts and the rubber is old but it's not crubling.

 

[acton mike]

even though the mounts are not broken, worn mounts can cause the engine/transmission to move around under acceleration - sometimes enough that the engine/transmission can come into contact with pieces attached to the body shell.

To check this out, get someone to help you do the following.
set the parking brake
get your assistant to start the engine, put the car in drive, step on the brake and feed it some gas (oh by the way, chock the front wheels)
while your assistant is doing this, you can stand to the side of the car and watch to see how much the engine moves

you might be surprised just how far it can wander around on soggy mounts

 

[martinv]

Update: It was the Right front drive shaft. This was replaced not so long ago but it probably has plenty of miles on it as I drive a lot.

It was the inner joint. I discovered what looked like grease leaking out. I think the band was maybe just loose enough that grease was getting out. You can see the grease on the right side band on the pic: