95' saab 900s shaking at idle

Bought the car for my girlfriend for a month, the problem came with the car (I had thought it's sign for strong engines :doh: )
The car (as title with 98k milage, engine 2.3l 4 cylinder non-turbo) constantly shake when I stop at a red light. (I tried changing gear to Parking it gets better but still a little.) When I changing gear from/to Rear, it will give a gust of strong shaking then back to normal. Otherwise the car run fine and strong, pretty smooth on highway or accelerating.
Anybody can give me some idea before I go to mechanics, or even better, tell me nothing to worry and let it be :laughing:
thanks

  arjiang

Nothing to worry about. Let it be. That's what you wanted to hear, right? Yeah. :thumbs:

Well, actually, something comes to mind. Motor mounts.

  DodgeRida67

Well, do you think I would have a prayer to find out which engine mount is broken by myself? My DIY level is self changing oil but I'd like to and think I can learn---except for it needs costly special tools.

  arjiang

Unfortunately, one of the characteristics of the first 2-3 years of the 2.3 Liter 4 cylinder version of the "GM" version of the Saab 900S (1994-1996) is that they all shake at idle. It was a problem when I bought my 900S from the day it was delivered. I brought it to the dealer numerous times, and the engineers in Sweden spent lots of time working on it, but they could not stop the problem. The essential problem is that the engine is unbalanced. That doesn't mean it is weak or will wear out fast...only that the designers did not seat it correctly in the engine compartment. All engines idle more roughly than when they are cruising along on the road. But, when the mounting is unbalanced, the shaking transmits itself into the cabin, resulting in entire car feeling as if it is "shaking" at idle. It is not harmful to the engine, nor is it a sign that the vehicle will break down. After about 100,000 miles, the front engine mount will need to be replaced, because the imbalance puts excessive wear on the rubber portion of the mount. That isn't going to cause the engine to "fall out", so don't worry. But, when you accelerate, the engine will unnaturally move upwards, putting extreme stress on the other engine mounts. For this reason, the front mount will need to be repaired if it has broken. It is a $250 repair at the mechanic's garage, or a $60 part for you to replace yourself.

There is virtually nothing you can easily do to stop the shaking, or the cracking of the rubber on this front engine mount, because the problem arises out of the basic vehicle design. You might be able to reduce it if you added shock absorbers, at strategic points in the engine, but that means a total redesign of the car by an amateur. You might also increase the idle speed, but that will significantly reduce your gas mileage in city driving. You will be best served by simply accepting the shake as a characteristic of the vehicle.

  Saabman

or have the reciprocating assembly balanced when you have the engine rebuilt....

or maybe don't even worry about it since the thread is 8 months old and he's probably given the damned thing away by now ... :banghead:

  dodger65

GM made those cars horrible. :banghead:

  FordFromHell351