We have a problem with our 1979 300d om617 auto when first started in the morning in "p" park the engine will idle and then come under load and feels like it's gone into reverse, I have to move the shifter/selector into "n" to release the load, same happens if sitting in "n" with the hand/emergency brake on it ,it idles then drops under load forward.The transmission shifts fine and isn't slow to select gears But when reversing it sometimes "locks" as though it's been slammed into "P" Park.....







I have adjusted the linkage and this hasn't made any difference to locking in reverse randomly I have also adjusted the kickdown linkage but these symptoms were before then aswell.......Any help would greatly be appreciated

 

My first though was that the Shifter Bushing were worn out. However, you sopke of adjusting the Linkages?
If you are speaking of adjusting Linkage Rod that goes to the Fuel Injection Pump that is not the Linkage that puts it into the Gear that you select with the Gear Shift.

 

It appears the previous owner bridged the neutral safety switch in the loom under the dash, so I removed the switch drilled the rivets out cleaned the contacts and tapped the holes for screws.
Before installing I noted the park position but more so the "N" position, and aligned / reinstalled the switch and aligned the selector lever up without moving the transmission lever and adjusted to I had the suitable selector position inside the car....Im guessing in "R" it was still partially in "P" and would grap the parking cog.....since adjusting the idle has come up on the engine in "P"or "N" so it's no longer under partial load.....it's just luck that neither my wife or myself accidently started the car in gear otherwise.....


many thanks anthony