'98 ZX2, 2.0L DOHC, automatic, 105K miles. Am replacing the ball joints on my cousin's car. She also told me that the right side motor mount (based on what she was told at Midas) needs to be replaced because of a vibration issue. The front tires were worn to the cords so I brought it home on a tow dolly to work on it (I have not driven it as of yet). The engine runs (unloaded/in PARK) smoothly (no missing or jerking), but there is a definite vibration that can be felt throughout the entire car. The vibration goes away above 1700 rpm. Even though I do not believe this has anything to do with the motor mount, I took a good look at it and see nothing wrong (properly mounted, no cracks, rubber still pliable) Any ideas/thoughts? Thanks for your time and consideration. Rob

 

Have you considered removing the drive belt for a short time to see if there is any change ?

 

I have not tried anything as of yet, but will look into that. Thank you for the suggestion.

 

Removed the serpentine belt and ran the engine for a short bit. Didn't seem to make any difference in the amount of vibration.

 

OK, let's try something else.
This is best done with another person assisting.
Have the other person apply the foot brake and shift the vehicle into drive , note if the engine lifts . Then try it in reverse and note the amount of movement. You could also have the person inside the vehicle with the vehicle in gear and foot brake held applied, then depress the accelerator a little not much and see what the engine does.
If it moves a lot the mounts are ready to be replaced. I'm sure you know not to stand in front of the vehicle when doing this, but I need to cover the safety aspect.
Let us know if you see anything unusual.

 

Why don't you think it's the motor mount? It sounds like the motor mount...or trans mount...

 

Agreed, you can't always tell by just looking.