1992 Mazda 929 engine Rattle noise only when parked or neutral.
The sound cams when I start the car. its a 1992 with 115k miles.
Ver annoying sound becomes noisy. When I put it in R or D gear or basically any gear it gets quite. When in P or N its starts again. the sound it makes is like if something metal were spinning on a rod/balancer and it was loose or the gears worn. I don't know. please help

 

It is hard to diagnose a noise on the internet but those were prone to wear out the rear transmission mount/stopper. What you describe is kinda what they do. Just pray you don't need engine mounts.