Transmission won't shift into Drive

[Benny Berry]

1985 300SD local drive, floorboarded into passing gear fine, but didn't ever yet shift back to drive. Drove the 5 miles home. Starting from routine stop it shifts I think its twice but will not go to regular drive speed gear. This has happen a couple time in the past two years but those times I did a quick accelerator to floor and release and it would shift out of passing gear and back into drive as normal. Lubed some linkage then it didn't fail. Now that action doesn't make any difference. Today looked at linkage and wiggled them and vacuum lines no real action taken, then went for ride and it was not shiftingup as should, had to do strong acceleration and let up to get shift ...but no way to make it go to normal drive speed. At 50 mph its doing about 3000 rpm which it sould be doing 70 at that rpm. Any thought appreciated. Thanks Benny

[t walgamuth]

but does this model have the electric down shift button under the gas pedal? if so maybe it is stuck or a wire crossed.

tom w

[mbz240d1981]

You have an internal issue. The passing gear is sticking. I had this happen on an SD.

What is your location in the states?

Ryan

[Benny Berry]

Tom, I will check for the switch under pedal. There is a switch on top of valve cover that is contacted by cam in the linkage assembly. Thanks for reply and will take a look later today. Thanks again.. Benny B

Ryan, I am located in Georgia about 45 miles SouthWest of Atlanta via I-85 and I appreciate your reply and will continue my think tank on this problem and listen to all responses on this forum. When bought these cars 8 years ago, bought manuals also but the transmission manuals were not avail and didn't persue, these are hard enough to figure out but are helpful, lots of help if ever find section you need. Thanks again...Benny B

85 300SD
90 300D

[reddog]

I just did my tranny which had the same symptoms as yours.(no fourth gear) Turned out the outside teflon seal under the fourth gear clutch pack drum was blown out, almost out of it's groove. Replaced all the seals, and reverse clutch plates. 82 300SD, 235k. reddog

[Pete Burton]

Could also just be the kickdown switch sticking. Easy way to find out is to remove the little screw holding the wire on the kickdown solenoid on the back of the transmission(cover the wire end with a piece of tape). If it then shifts into 4th, it's the switch.

[Benny Berry]

Reddog, sounds like you figured it out, did you do it yourself and what approx cost are we looking at. Mine is 85 w/215k miles and has good history and condition.......another thing is a strange roar sound that resembles truck tires was what I was trying to figure out when this transmission shift problem came about. Roar/humm is not real rough or loud, wheel bearings seem ok on jack and spin wheel test. Wonder if it is related to current trans problem?
I really appreciate your response and personal experience. Any further comments will also be glad to get. Benny B

[Jim H]

Originally Posted by Benny Berry

...it would shift out of passing gear and back into drive as normal.

FYI to anyone interested, there is no 'passing' gear. The term 'passing' gear is older than I am.

All it means is a downshift one or more gears 'lower' than you are in, to increase engine rpm and torque for better acceleration.

It is possible to be loafing in 4th at a low rpm, and command the transmission shift down to 2nd or even 1st.

Best Regards,
Jim

[Benny Berry]

Pete Burton, I like the sound of that, I did check the action of a switch on top of engine (think it is the kickdown sw) with a meter and the switch was closing and opening as throttle linkage cam hit and the wires to an from it seemed OK about 51k ohms through them that I suspect go to/thru solenoid, but I am going to do more looking etc under the vehicle and will do your test for sure. I really like the good response and good information Thanks Benny

[Jer]

The switch on the engine is the idle switch. The kickdown switch is behind the accelerator pedal INSIDE the car, in the footwell.

[Pete Burton]

A "roaring" noise coming from the trans in third gear can be caused by the planetary set. It's not common, so wish that one away!

[Benny Berry]

OK, After Jim H. got me straight about nomenclatures&functions ...things got better,thanks Jim. Everybody gave me a lesson about the tranny, Jim,Pete,TCA,Ryan,Tom and webmaster I thank everyone. Here is the good stuff, pulled wire off at solenoid..ran and shifting was beatiful right on into 4th, checked the kickdown switch under pedal...physical binding will deal with that soon.I am new at using this forum and it has been a great experience. Thanks to all Benny Berry Georgia USA Hope I will be able to help someone soon.