MoogieBoogie wrote:My car is a 1991 240SX SE FB 5 speed. When I start the car, there is a brief shake. The car has 135k miles - could this be the motor mounts?
Most likely. If you want to see - pop the hood. Have someone start the car while you stand by the engine bay - you will probably see the motor try to "jump" out of the car. Does it shake otherwise - i.e. at idle, in traffic, etc - most likely your motor mounts.
MoogieBoogie wrote:Also, there is some vibration in the rear hatch (rattle). Is this a common problem with a definite fix?
Yes, it is a common problem. I'm guessing your rubber stoppers have worn away. Pop your hatch, look on the frame/chassis toward the ouside corners right above the taillights. There should be a rubber stopper on either side. One or both are worn out.
You can either buy new stoppers or do the 5 cent trick - i.e. keep gluing a nickel (or even a penny) where the rubber stoppers are suppose to be until the hatch rests firmly on the piece.