My brother in laws 1973 450SL has devloped a unique problem. When the engine is started and put in drive or reverse, the engine rpms's suddenly drop way down but without the transmission really trying to move the car. Think of it like you left the parking brake on. It's just kind of bogging and bucking the engine without really moving.

Now if he puts it in park, and revs it slightly, the car will seem to want to creep forward! Not drastically, but if it had a manual tranny, I'd say someone was slipping the cluth heavily.

Any suggestions? His worst fear is the tranny or torque converter is gone. Another friend said check all vaccum lines, maybe somethings not engaging as it should.

Thanks for any help!

I know this is sort of basic, but I have seen low or high fluid level cause weirdness like this. Be sure when cold and level, the fluid is 10mm below the bottom line. When warm, it should be at the bottom line, not to exceede the top one.

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Benzmac:
1981 280GE SWB
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

surges....
 

I have had the same problem when i first bought my 450se, ended up being low transmission fluid. Runs great after it was topped off. Give that a shot.

Compressed air in the hydraulic servos will do funny stuff on an auto tranny. Fluid check is the first thing I'd check.

It's possible the tranny is shot, but I'd verify that the fluid and filter are good before worrying about a bad tranny.

Peter