1991 Mercedes 300 TE won't shift out of 1st help!

Hello All:
I am a brand new subscriber as I am a brand new Mercedes owner. Long story short, I traded a case of books for a 1991 300 TE 4 Matic.
I as told that the front suspension coil was broken (what a saga so far!) and that the transmission *might* have a problem (stop laughing...). The car shifts into R and N and D with a little difficulty (it seems like the linkage isn't as "tight" as it should be - for example, I need to push forward with the gear selector when it is in Park to start it, otherwise the car thinks it is in gear. Trouble is, the car will only stay in 1st gear once it is in D - it never upshifts from the lowest gear. 25 mph tops before I am afraid somethings gonna give. I spent some time looking through old posts and felt that the top 3 (cheapest) things to do were to drain transmission fluid, replace the filter, replace the modulator, and check to make sure the kick down switch wasn't stuck. I am about to do the fiter and modulator and the switch seems, externally anyway, to work. Is there anything else I should do? I am afraid if the tranmission does not work properl after this, the wife is going to say "To the junkyard!", a real shame given that this car has 155,000 miles on it and the motor seems like it is in very good shape.
Help!
Thanks,
Jim
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Must have been some books to get a car in exchange!
The car starts off in 2nd gear by default. That's done to avoid stop light creep of the 1st gear's high ratio.
You should know that the transmission is a 4 speed and that 1st gear is engaged either by shifting into L at a dead stop or by kick down.
Let's say you wanted to start off and shift it manually. At dead stop shift into L, drive off then upshift to S then immediately back to L to hold 2nd gear, then upshift appropriately to S (3rd) and then on to D for 4th.
You're on the right diagnostic path but I'd suggest you think about the priority of events, in order of labor and repair cost.
1. Kick down switch (under the accelerator pedal), easy to check, clean and check for grounded wire(s) under the car.
2. I believe the transmission linkage has some rubber grommets that may be missing from your car, creating linkage slop.
3. Suggest you check the motor mounts for the whole motor / transmission assembly may be out of place causing these shifting problem(s).
4. Changing the transmission fluid & filter is a good step, drain the torque converter as well (turn the motor until the drain plug appears). When replacing the transmission's pan be sure to NOT over tighten the bolts as the pan will deform and leak.
5. Modulator? Others here will have to speak to that.
Parts are available for virtually everything so nearly everything can be repaired to be as new. Suggest you check www.autohausaz.com and / or www.performanceproducts.com and / or www.thebenzbin.com
Finally, unless you NEED a 4-matic station wagon consider selling this complicated (and abused) car; buy a 300E if an M-B appeals to you. The 4-matic and the wagon's rear suspension adds complexity (cost) and weight.
Best of luck with your project.
--

2008 T.G.Lambach. Publication in any form requires prior written
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I don't think modulator would have any issue with the problem you are having now...
Definitely do the transmission fluid and filter change Clogged filter would affect the shifting as my friend had an issue with his car... car won't shift out of 2nd gear... his mechanic changed the fluid and it shifted normally afterward until it crapped out about 12,000 miles later. His car is a diesel and the mileage was at 270,000 miles when the original tranny died.
I would definitley check the linkage for missing grommet... get new one from dealer nad use plier to press them in. This affects the position of the safety switch that prevents you from starting. However, my first MB had one missing grommet and I was able to start car with no problem. so I am thinking... maybe your car was in accident and the position of the linkage is way off.
Every shift down... so how it is in relation to the shiftgate... is it that far off? If not, then I would change out the safety switch...as it is bad.
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Hello, again:
Thanks for the advice. I will report back once I change the fluid and filter. I can reach the linkage where it attaches to the rod that comes down from the shifter - the linkage going back to the top of the tranny fits into a hole at the bottom of the rod coming down from the gear selector - is this where one of these rubber gromets is supposed to go? There is nothing there now, so that there is a lot of rattle and play there. Also, where is the torque converter relative to the transmission pan?
Thanks,
Jim
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Hello, again:
Thanks for the advice. I will report back once I change the fluid and filter. I can reach the linkage where it attaches to the rod that comes down from the shifter - the linkage going back to the top of the tranny fits into a hole at the bottom of the rod coming down from the gear selector - is this where one of these rubber gromets is supposed to go? There is nothing there now, so that there is a lot of rattle and play there. Also, where is the torque converter relative to the transmission pan?
Thanks,
Jim ---------------------------------------------------------------- Before you do that, try unplugging the connector from the downshift switch under the gas pedal.
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Hi:
Thanks for the advice. My problem with anything to do with he kickdown switch/wiring/solenoid is that, given what T.G. states above, it seems unreasonable to believe that the car is operating in the lowest (kickdown) gear. Rather, it seems to me that the car is operating in 2nd gear, which would square with what T.G. wrote. I can't believe I could drive down the road at 25 mph or so in the absolute lowest gear - 2nd seems much more plausible. Given this, how could anything to do with the kickdown operation be at fault?
Thanks far all input.
Jim
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The speedometer should have upshift markings on its number scale; look for a I at about 25 mph, a II at 45 mph a III at 65 or 70 mph. My speeds may be off but that's the easiest way for you to know in which gear the transmission is running. The engine will be at about 5,000 rpm when you reach each mark in the gear indicated. Also, 1st gear is very steep by which I mean the car will jump when you bump the accelerator - that's why 2nd is the default idle and start off gear.
The torque converter is inside the "bell housing" immediately aft of the engine block. The bell housing will have a detachable cover on its bottom so one can reach the torque converter's drain plug. One usually needs to turn the motor so have a helper "touch it" with the starter while you watch for the plug - don't reach inside until the ignition key is back in your pocket!
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http://www.detali.ru/cat/oem_mb1.asp?TP=1&F 4230%5F44Q&M3%2E985&GAr2%2E342&GMq7%2E447&
This is the top page of this car's parts diagrams. One must scroll down to the diagrams as they're near the bottom of their respective pages. The diagrams cover all the car's systems.
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-->> T.G. Lambach <<-- wrote:

http://www.detali.ru/cat/oem_mb1.asp?TP=1&F 4230%5F44Q&M3%2E985&GAr2%2E342&GMq7%2E447&

I'm always puzzled on how you guys manage to navigate that Russian site. Do you speak Russian TG?
X.
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Hi:
Thanks for the advice. My problem with anything to do with he kickdown switch/wiring/solenoid is that, given what T.G. states above, it seems unreasonable to believe that the car is operating in the lowest (kickdown) gear. Rather, it seems to me that the car is operating in 2nd gear, which would square with what T.G. wrote. I can't believe I could drive down the road at 25 mph or so in the absolute lowest gear - 2nd seems much more plausible. Given this, how could anything to do with the kickdown operation be at fault?
Thanks far all input.
Jim ----------------------------------------------------------------------------- It would take less time for you to disconnect the kickdown switch than for me to explain why. Just trying to help.
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I would try what Chas suggested.
As for the freeplay... yes, you lost alot of them. There should be two bushings... one at tranny and one from where the shift gate come down to the linkage toward transmission.
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In addition to the other comments in this thread, it is worth to know, that the shifting is controlled as a balance between the modulator output (proportional to car's speed = A/T output shaft speed) and the throttle position (~ proportional to engine's load). Each gear ratio has a shift valve whith its own threshold.
So the problem could also be in the cable linkage from throttle to A/ T, including the device at the A/T end of the cable. This device also has a vacuum connection (E/S selector).
If modulator and cable linkage is OK, then the problem is in the internal hydraulic control system. That's where the change of fluid and filter comes in.
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