weird issue
 

I was driving my 1987 300 E and all of a sudden it seems to rev high but not match the speed. i.e. it seems like the transmission slips at high speed, however the transmission seems ok as in it engages well and does not jerk, Also it was rebuilt about 18 months ago. Could it be anything else, note it does not happen always. If there is too much transmission fluid could this happen? There seems to be about 3/4 quart more than there should be.

Thanks

Over-filled transmissions can act up because when they are too full, the fluid gets air whipped into it. An automatic works on Hydraulic pressure and air in the oil can cause the pressures to drop. Pull the drain plug on the bottom of the pan and set the level.

Are you observing what you mention on the tach? If the tach does not indicate the engine is revving, then suspect that the fan clutch is engaging. The added engine compartment noise can fool you to thinking the engine speed has increased. If this is the case, suspect a cooling problem.

Steve