Do you mean that the linkage on the side of the gearbox (which you'll need to be under the car to pull on) moves through all positions, i.e., you can count the detents for P, R, B, D, etc...[/quote]

This statement appears to the most accurate. While I was replacing the bushings, I was able to move the linkage through the positions by hand seemingly without issue. Once reassembled to the shifter all worked well until I started the car and now It is the same running or not. The car has been on jacks the whole time. I'm a little hesitant to disconnect the linkage and try to shift the car while under the car. I'm sure you understand. I have changed the fluid a filter and it has made no difference as I suspected.
I must have done something to the neutral safety switch because I have to jump the leads by the battery to start it up. Nice

>>I was able to move the linkage through the positions by hand seemingly without issue.

Yes, that's OK, but it sounds like the fault was not present when you did that test.

Unless I'm missing something, if the vehicle's wheels are well chocked, and you've got the parking brake applied, there shouldn't be a safety issue in disconnecting the linkage and operating it from below (engine off!!).

If you find you cannot operate the linkage through it's range with the selector disconnected, then, you *know* the problem is internal to the gearbox, and isn't to do with the setting up of the linkages, and shifting on the mountings.

I know that I'm taking lots of time, and asking lots of questions, but, in my experience you have a much higher chance of success with automatic gearboxes if you *know* exactly what fault you're looking for before you open them up. The alternative methods tend to waste lots of time and money!

The wheels aren't chocked, I've got the car resting on jacks with the wheels spinning free. I am leaning towards an internal issue as you mentioned before. The only thing that troubles me, is why won't it go into L? The reverse/park issue applies to your suggestion of a valve or governor problem. It just doesn't explain not going into L.
I will have an opportunity this afternoon to remove the linkage again since it's not working right and see if I can move it through the positions again without incident.

Don't sweat it over the amount of time your taking. I'm thankful for the advice and would rather spend time learning from the folks who know more then wasting time and most likely money on trying to figure issues on my own.

Don't be crawling around under that car if it is only on jacks. Make sure you get jackstands under it before putting your body at risk.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Sorry, yes, I misread / misinterpreted your post - if the car is just on jacks, **don't go under it!**, it's not safe. You do need something solid like some stand or ramps before you risk your neck going under a car!

Jack stands not jacks. She rests safely on four sturdy jack stands. Rest easy, I may be dumb but I'm not stupid!

I'm glad your car is well supported - I was worried for a while!

>>It just doesn't explain not going into L.

It could do - I know that some MB gearboxes use the hydraulic detent to also block the lowest forward gear when travelling at speed. I don't have a source of sufficiently detailled information that would allow me to pinpoint whether this is or isn't the case for your specific gearbox.

*If* you do determine that the fault is within the gearbox, there are 2 tasks to consider;

The governor is to be found behind a circular cap at the rear driving side (LHD) of the gearbox, in the tailpiece housing. This should be removed, stripped, checked, and cleaned. I think I've seen another thread on this site that describes how to do this - sometimes there's a plastic gear in there which sometimes breaks.

The detent plunger is found in the valve block, which you can get to by removing the sump, and, when actuated, the end of the valve sticks out of the valve block and interferes with the movement of the internal parts which connect between the external linkage and the main selector valve. It should move freely - however, if it has been forced against, it's possible that the valve itself has been deformed and may no longer slide freely in its bore.

The governor is to be found behind a circular cap at the rear driving side (LHD) of the gearbox, in the tailpiece housing. This should be removed, stripped, checked, and cleaned. I think I've seen another thread on this site that describes how to do this - sometimes there's a plastic gear in there which sometimes breaks.

The detent plunger is found in the valve block, which you can get to by removing the sump, and, when actuated, the end of the valve sticks out of the valve block and interferes with the movement of the internal parts which connect between the external linkage and the main selector valve. It should move freely - however, if it has been forced against, it's possible that the valve itself has been deformed and may no longer slide freely in its bore.

Will I have to drain the fluid and remove the pan? I'm guessing yes particularly when it come to task #2.

For info on the governor, see here;

Transmission 722.418 Governor Test Question

Yes, you'll need to drain the oil and remove the sump to get to the valve body for task 2.

Thanks for the link. My symptoms seem a bit different. The other issue is I have to manually shift from S to D and it still has no power. This was before I cleaned the "banjo" bolt and replaced the levers on the top of the valve cover. I Don't know if these problems are gone yet as the car is still on jack stands and I thought the shifter bushings would solve the problem we've been going over.
I am going to try to get started tonight with your suggestions.

Thanks again Bill 1984 300TD

I see that you replaced the shifter bushings.

There are 6 bushings total (most only know about 2 of them). In addition to the 2 that connect to the shift rod under the car, there are 4 more in the shifter box just under the shift lever. I just replaced them all on my 2 diesels and found about half of the bushings were shot.

I adjusted the length of the shift rod too, so that the shift lever lines up perfectly with the digits.

Easy job. Shifts like new.

>>My symptoms seem a bit different.

Yes, but the reason I posted the thread was not because you have the same symptoms, but, because it describes how to remove and work on the governor valve.

Noted: I think I may have to pull the transmission anyway. She will not start with the key, I have to jump the wires by the battery and she fires right up. New problem. I tried to look at the NSS and everything appears fine, but to remove it you must have hands like a 5yr old and matching mini-tools.
I took her off the jack stands and went for a spin. Definitely more power and I attribute this to cleaning the Banjo fitting. I tried to count the shifts and reached only two each time. 50MPH@2000RPM I'm guessing this is 4th gear? It sure feels like she is starting out in 2nd but I'm not sure. I've been told you don't have much of the line with these cars but this is ridiculous. I'm going to get run over by dump trucks and semi's if this is how they really are.
By the way park isn't holding now. almost rolled into my 2006 Vibe. That would have been fun explaining to State Farm.

>>She will not start with the key

If anyone has been pulling at the locked out gear selector, it's possible that you need to adjust the shift rod. i.e. when your selector in the car says it's in neutral, owing to shift rod mis-adjustment, the gearbox may think otherwise!, and the NSS is correctly blocking the engine from starting.

As a quick test, with your foot on the brake, and the key held in the start position, give the selector a jiggle up and down a gear position or so. Does the car start?

I still don't think you *need* to remove the gearbox.

Drove the car to work today. Tried the jiggle test you suggested in all positions and no luck. I have to jump the terminals to start the car. Not a big issue, but I don't want to continue to do this for too long.
Anyway, I must shift manually to achieve moderate acceleration. If I leave the shifter in N which is really D, absolutely no power and it feels like there is slight slippage. I'm guessing the car is starting out in 2nd and trying to down shift to 1st. It is truly a creepy feeling, unnatural.
While I was under the car last night before I took her off the jack stands, I tried to check all vacuum lines I could reach and everything appeared normal. It has a green module I wiped away the grime to verify. The locks are moving slow but they are moving, Should they snap up and down like electric?
The only way to get it in park is to shut the engine off, this points to what you suggested about the governor.
Is there any way to remove the Neutral Safety switch without removing the transmission?