decon.paul

84 300D was having some down shifting issues last week, oil smelled a bit burnt so changed it with filter over the weekend. On the test drive everything was great. Today Not so much. Down shifts on even the smallest grades much worse over the day. (was minor before,this was the reason for the oil change, yes dex 3) last hill before home in solid traffic i dropped steadily from 45mph down shifting to possibly 2nd at 23mph. Ran solid after until I got home and started checking. No reverse. does not want to move forward with mod pedal in any gear. did take a sec to shut down after key off but the last vacuum issue i had did not affect the trans like this. oil is approx half way up the stick but then the thunderstorm rolled in so I am looking for something to check if the rain lets up. Kick down switch is unplugged and has been for a while.

ECSTuning

decon.paul,

A few things:

First, are you checking the transmission fluid with the engine running and the vehicle at normal operating temperature? If you are not, then you are getting an incorrect fluid measurement. Transmission fluid half-way up the stick sounds to be extremely over-filled. Check it again, with the car at operating temperature (~80° C), on level ground with the engine running (car in Park). If the fluid is still half-way up the stick, then you may need to drain some out. How much did you put in when you did the change?

Second, you mentioned that the car took a few seconds to shut off after you turned the key to the off position. This is a symptom of a vacuum leak. Vacuum plays a major role in the way the the transmissions in these cars shift, and if you have a leak, then the correct vacuum is not being applied to the transmission modulator which will affect shifting. Replace any broken / cracked vacuum lines.

Rmac58

^ Agreed.

Burnt smelling fluid = not good.

I will suggest doing a drain and fill, replacing the filter and using a new gasket.