Well I hope this is not terminal.I was driving on the interstate today and all was fine.I drove about 20 miles and got off the exit. When I went to accelerate the trans slipped and did not want to shift right. Long story short now it will not shift into high gear and on take off it feels slippy. I am going to drop the pan and change filter out this next weekend to see if it helps.Also when I go to put the car in park the shifter sticks and you have to work it to go to park.

 

It sounds like your linkage is screwed up. If the bushings wear out, then you could be only partially in gear, or possibly could be putting it in 2nd. Same with the park thing.
What year/model is your car?

 

Sorry I thought I included this info,83 300D. I am going to try and get it on some ramps and drain the trans fluid and replace the filter.Does this have a drain plug or is it going to be a mess?I have tried moving the shifter while driving and never could get it to shift to high.I tried to drive it this morning to see what a cold transmission would do.When I put it in reverse it never really engaged.When I put it in drive I didn't think I would be able to get it back.No matter where I put the shifter it wouldn't engage. After about 5 minutes it finally crawled back in the driveway. Oh and mileage is over 300k

 

My 84 300D has a Drain Plug to drain the ATF.

Last week my trans stopped working in First Gear (not working in D or Low). The rest of the gears work. Have been putting the shift lever in 2nd and starting in 2nd gear; this works because of few Hills in my area.

My research and what other forum members on anothe foru have told me it is a B2 piston issue.

If that is the case it would be an easy fix except for ther fact that the Transmission Tunnel only allows about 1 inch of space.
Concensis is you have to force the trans to one side; wedge wood to hold it to gain access.
The Diesel Giant website a how to do but he used a 126; which is easier to work on.
He could have other transmission info.

 

B2 is a 1-3 hour job depending on beer consumption and whether you have the car up on a lift. It's a much easier job if you also have the exhaust out of the way. Yes, you will need to wedge the transmission out of the way. On a 123 body that will give you about 3" space.

This guy's problem sounds a lot different, and I would start with the shift linkage.

 

Well I dumped the fluid and dropped the pan the other day.The oil was surprisingly clean as was the inside of the pan. The pan had just the slightest amount of buildup in it and cleaned easily.I drained the converter and refilled with the proper amount of fluid. It seemed a little better but not much.

I was driving it before and the trans had no slipping issues or shifting issues.The shift from first always hit a little hard, mostly when cold but all the other shifts were nice and clean.I have taken that and ruled out burned discs.I have taken the valve body out and it is going to the shop as I type.One thing I noticed is the plunger that connects to the shifter was really free.I mean you could tilt the body and it would slide in and out. Is that to loose? I hope this is a sign the seals in it are wore out.

 

I am still having the same issues with my x-fi card after the fix. there are new drivers coming out in a few weeks for the card so maybe that will clear up my problem

 

Well the shop that was going to rebuild my valve body gave me one to try before rebuilding mine. No difference to the way it shifted and still slipping.Talked to a transmission repair guy locally and he said sounded like a torque converter to him. Said it like he knew for sure also said 500.00 haha. I am going to take it to the guy who loaned me the valve body as if he replaces the torque converter and it still not right he will not eat me alive tracking down the issue. Also all he works on are Mercedes diesels and I would like to have him look at a few other things for me i e... Slow to shut off and charging issue.

 

Maybe the whole problem is a vacuum issue if it's slow to shut off.
Charging could be a coincidence, or your key switch could be bad.

 

Well got her back Monday and all seems good.Shifts are smooth and shifter seems tighter. Now I get to replace some motor mounts this spring. Is this something I can do? I am not afraid to tackle this now the trans was another story.