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  #1  
Old 04-20-2008, 09:04 PM
B_C B_C is offline
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Question 124 won't shift

My 1991 300D 2.5 Turbo with 722 418 transmission will not shift out of first gear. I've owned the car over a year and except for shifting a little hard when cold the transmissions been OK until one day when it just stopped shifting. I've disconnected the downshift switch beneath the accelerator and made sure the Bowden cable was adjusted with the slack taken up but not pulling. I'm not sure where to go from here. My first for everything. MB, diesel, posting.
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Old 04-20-2008, 10:07 PM
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Have you checked fluid level? If you can't get to operating temperature in first gear, the fluid level should be about 1cm below the low mark on the dipstick with the engine running and shift lever in P. What's the condition of the fluid (color, contaminants and smell)?

I understand the kickdown actuator can jam. I don't know if it's accessible from outside the transmission.

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Old 04-21-2008, 10:26 PM
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The fluid is red and there is no burned smell. With the temp about 65 and the car at idle in park the fluid is 12mm below the low level mark.
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Old 04-23-2008, 11:02 PM
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Next thing I would try is disconnecting the kickdown solenoid at the transmission. It's the single wire going into the very back of the tranny, on the passenger side. What happens if you drive the car and let it wind up to 5000rpm in first gear? Will it upshift, or stay at 5000-5200rpm in first gear? The fluid level sounds acceptable.

The kickdown solenoid *might* be stuck, and yes it can be replaced externally... ATF will drip out while its removed though. BT, DT. I had a faulty solenoid, not a faulty valve... mine wouldn't kick down at WOT. That's the opposite problem though.

If the kickdown valve is good, it sounds depressingly like an internal failure, meaning a rebuild could be in your future.

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Old 04-23-2008, 11:04 PM
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Quote:
Originally Posted by B_C View Post
My 1991 300D 2.5 Turbo with 722 418 transmission will not shift out of first gear. I've owned the car over a year and except for shifting a little hard when cold the transmissions been OK until one day when it just stopped shifting. I've disconnected the downshift switch beneath the accelerator and made sure the Bowden cable was adjusted with the slack taken up but not pulling. I'm not sure where to go from here. My first for everything. MB, diesel, posting.
Whats the update on this B_C?
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Old 04-23-2008, 11:05 PM
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Edit - based on this additional information, via email:

Basically it was fine and one day it won't shift. Only first and reverse. Stays in first as far as 4k RPM and will slip into neutral when you let off and coast. Step on accelerator and will kick into first when the revs get to around 3K. Adjusted Bowden per forum, fluid not burned and at proper level, 12mm below low level, for a cold tranny. Disconnected vacuum line to tranny, no difference.

What's described above is more than a stuck kickdown valve. It shouldn't slip into neutral, it shouldn't need to rev to 3k before kicking into first. Bowden is absolutely irrelevant, you could disconnect it if you want. A total shot in the dark is a failed front pump, but if that's not it, you're looking at a tranny rebuild. This didn't happen shortly after a fluid & filter change, did it?

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Old 04-23-2008, 11:13 PM
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Maybe a flush toasted the trans? Common way to kill a good transmission.

I'd have control pressure tested, a trans shop should be your next stop.
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Old 04-24-2008, 09:13 AM
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No flush or fluid/filter change in recent or past history. Any recomendations for a shop in Atlanta? Wasn't expecting this at 187K.
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Old 04-24-2008, 11:12 AM
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I don't know any tranny shops in Atlanta, but Rusty Cullens (of *************** fame) is in Atlanta... you could give him a call, I know he can recommend a place or two. 800-741-5252, or email rusty@***************.

Sometimes weird stuff like this happens, even at relatively low miles. My sister's '87 300D tranny failed at 220k without any warning, one day it was fine, next day it refused to move an inch, regardless of gear selector position or RPM. What was really frustrating was the fact they had just pulled the tranny within the past year and done a full re-seal, d'oh! All that work for basically nothing. We never did find out what part failed inside, and instead swapped in a Peter Schmid rebuild. The new trans has been working fine so far...

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Old 04-24-2008, 03:23 PM
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Thanks for the name, I'm slowly making my way up the learning curve. Even though the fluid level is OK judging by where it should be when cold, I'm thinking about adding to it and see what happens. It's not my luck that it would work but what do I have to lose but the cost of a quart of tranny fluid.
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Old 04-24-2008, 03:37 PM
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True, it wouldn't hurt... even if it just adds some peace of mind. But only add a half-quart! That should move the level up about 10mm on the dipstick. You don't want to overfill, these trannies don't like overfilling. Use a Dexron-II or Dexron-III fluid.
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Old 04-24-2008, 09:26 PM
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Well a pint of fluid did no good, surprise, surprise. Got the name of a place to call from Rusty so I'll trailer it down and see if they can give me a diagnosis. If it comes to rebuild I won't be able to do that, but to replace it is within my realm. Who has pulled and installed a transmission and what would be their advice I wonder?
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Old 04-25-2008, 01:47 AM
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I have not pulled a tranny on a 124, but from what I've heard, you'll need to get the car jacked up as high as possible, to make room underneath. You'll either need a trans jack, or a couple of strong friends to get it in & out of position - it probably weighs about 150 lbs or so. It's not a fun job, but not terribly complicated either.
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Old 04-25-2008, 02:01 AM
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Oh, be a man Lower it from the engine on a floor jack, roll it gently off the floor jack onto a cardboard sheet or leak catcher pan, slide it out through whatever clearance there is. Installation is the reverse of removal.

Sixto
87 300D
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Old 04-25-2008, 11:12 AM
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2nd the "Not fun, but not complicated" part...

It was not fun, but certainly "do-able", especially with it on the lift

You'll need to lower the exhaust (not remove) and go in on the upper trans bolts with a loonnnnnng extension. Those were the biggest pain. Other than that, just make sure you have everything disconnected before you try and remove it. A transmission jack is not necessary, but would be helpful. If you are cheap like me and don't want to buy one, a piece of wood on the jack pad to support the tranny will work. This is definitely a two person/multiple beer break job, but not hard.
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