Help! Vibration problem even while in Park

[JWBeaversII]

Hi,

I have a '97 Park Avenue (not Ultra), about 76,000 miles.
My water pump went bad the other day so I replaced it. Afterwards, I've got this vibration problem (although it may have started earlier and maybe I didn't notice). Here's the details:

1. Vibration is not really noticeable when car is idling (around 750 rpm)
2. Vibration is extremely noticeable over 1,000 rpm, worse at 1,500, and a little better over 2,000.
3. Doesn't matter if I'm in Park, Neutral, Drive, or Reverse, or what speed I'm driving at.
4. Applied pressure to engine around mounts and determined that vibration goes away with tension.
5. Determined that the front transmission mount had a tear. Replaced front transmisison mount. Vibration lessened (before replacing, the car felt like it was going to vibrate apart while going down the road, now it's still very bad, still to the point where I feel something could get ruined by the excessive vibration, but better after replacing the mount.)
6. Took it to a friend who's a mechanic. Got the vibration to go away by applying pressure to the rear transmission mount. Replaced it. Old one didn't look too bad. Bit better, but not appreciably (esp for $300).
7. After all this, took it for a drive. After about 5 miles, the vibration went away! Was in 2nd gear at the time getting onto a highway. I let her fly and it was fine up to about 90 mph. After that I slowed down to exit and while on exit ramp, noise came back. Hasn't left since. It occasionally will get better/worse on its own like this, although that's the only time it went away completely.
8. Totally stumped, please help. I can still get the vibration to stop (?) by applying pressure with a pry bar on engine around engine mounts. Only two left, but they look fine. Don't really want to replace anymore if I don't have to as they are extremely expensive. The path we have been taking is that the engine is fine (sounds fine, runs fine, shifts fine) and the engine mounts are not doing their job. I'm thinking maybe they're ok, but the engine is vibrating too much. But must admit, I'm brain-dead on this one right now.

Any thoughts would be appreciated.

Thanks,

James

[Flatrater]

Take your serp belt off the engine and see if the vibration goes away. If it does than your problem is with something run off the belt.

[JWBeaversII]

Hi,

Sorry for the trouble. I figured it out last night. I had to remove the motor mount to replace the water pump. There are two small spacers and I thought they were the same size. Turns out they aren't (4 mm difference) and I had them reversed.

Thanks for the info.