Speedometer needle bounces up and down when driving
 

Speedo has been acting weird on and off for a while, but today picked the car up from my mechanic the speedo is bouncing everywhere and te car is hesitating. It was doing this before, but only at hire speeds. he did the timing belt, water pump, all the seals, balance belt, ac belt, power sterring belt etc. After the install the motor is idling odd as well. we think the funny vibration at idle may be the rear mount being worn. needless to say te car is not running the way it was before the work. Mechanic pressure washed motor after all was done wondering if some thing got wet. any help would be great.

Has the check engine light come on?

You may want to have the mechanic recheck the timing marks (a possible belt off by one tooth). A timing light would help verify a problem.

The speedometer gets its signal from the speed sensor on the transmission. You may want to unplug it and see if the pins are corroded or maybe the connection is loose.

re
 

he checked te timing and he stated it looked good.

no engine light came on.

I will have him pull the sensor tomorrow. Needless to say I am not happy about any of this. The car was running awesome before I took it in for service.

re
 

if the belt was off by one tooth how would it feel? he thinks the rear mount may be going bad.

Checking with a timing light is only part of the issue. It would be possible for the camshaft to be one tooth off timing, but the distributor could be adjusted to bring the spark timing OK.

If the cam timing were off the engine would run pretty bad. Either lose everything above 2500 rpm, or (if its off in the other direction) it wouldn't idle well.

Check out the rear mount, at least to rule it out. Automatic or 5-speed? Automatic would have a vacuum-operated rear mount & maybe the pressure washing has disconnected a hose?

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he pulled it apart today and the balance belt was off by one tooth. seems to be doing better still feels a shade tight but that could be from all the new belts?

Explain what you mean by "feels a shade tight"...