2001 Saab 9-5 auto box.

[millerman]

When selecting reverse, more so when hot, the car vibrates quite a lot accompanied by a machine gun sound. This only really happens when the car is creeping/on a light throttle, if i accelerate in reverse the noise/vibration goes away.
Any explanation please.

 

[Burnerman]

Complete guesswork this, but as a gear is selected, the engine revs drop a little and the engine will tend to rock more on its rubber mounts.
Any sign of excess engine movement (failed mounting maybe) or perhaps the exhaust system knocking on the bodyshell?
John

 

[Mursal]

You probably notice it more when hot as the engine would be running harder just after starting. Hopefully nothing more than mentioned above, but check your transmission oil level. You should have an oil level dipstick under the bonnet for the transmission.
Usually checked with the engine running and the transmission in the park position, but the handbook will tell you the full story. If the problem is in the gearbox its a replacement box I'm afraid. Might pick up one from a breaker, but he'll know what its worth.

Let us know how you get on.

 

[millerman]

Its not looking good guys, i went out lunch time, engine revs increased but the car bearly moved, got to a hill a few hundred yards from my house and the revs went through the roof and i was hardly making 40mph. Matters did improve somewhat when the engine warmed up after about 20mins.
ATF fluid level is correct after checking with a hot/running engine, its looking a little brown rather than pink, also had a slight smell, think its time for a fluid change!