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  #1  
Old 07-07-2007, 11:50 AM
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Unhappy 87 300D tranny problem - no engagement in any gear

Hi everyone,

My sister's 1987 300D tranny suddenly died. There was no warning, no symptoms... it was shifting fine, no delayed engagment, no slipping or flaring, nothing like that. They had driven it home, parked it, went to move it later and it refused to engage any gear (R, D, S, L). Nothing. No noises, just zero movement. They let it sit overnight so it was cold, tried again, still nothing. Engine runs fine. Mileage is approx 200k. It was re-sealed within the past year and is 99% leak-free. Fluid level is normal and looks/smells fine.

I found in the WIS that a quick test of the front pump is to start the engine and disconnect one of the cooler lines at the radiator... if fluid flows out, the pump may be ok... if not, the pump is dead. He did this, and there is flow with the engine running (compared to the gravity drip with the engine off). I'm assuming this means the primary pump is OK. (??)

Any ideas as to what the problem is, and how to fix it? My BIL is capable of pulling the tranny if necessary, and working on it on the bench. I can't in good conscience recommend a ~$2k replacement or rebuild, since it was shifting perfectly until two days ago. I figure it has to be a piston, or pump, or somthing else relatively simple...??

BTW, for the brave folks who want to attempt 722.3 internal repair, click here for a 7MB factory PDF file with diagnostic & repair procedures. (Unfortunately there was nothing related to the symptoms I described above.)



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Old 07-07-2007, 12:14 PM
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I don't have anything constructive to say except yikes! Thanks for giving me something else to worry about, Dave. My '87 has had shifting issues as long as I've had it and I still haven't figured out whether they are vacuum-related or whether the tranny is slowly dying---I'm at 220K mi and it could be the original one for all I know. (That's a shameless invitation to my thread about it here...)
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Old 07-07-2007, 01:47 PM
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I replied to your other thread.

I found someone else with the same symptoms (no forward or reverse), but there was no post reporting what the final solution was... maybe he just installed a rebuilt tranny:
http://mbca.cartama.net/archive/index.php/t-5814.html

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Old 07-09-2007, 06:07 PM
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Update

My BIL pulled the tranny out of the car, and compared it to the spare tranny on the bench. There is NOTHING visibly wrong with the pump or torque converter. Both look identical. He called the local MB tranny expert (recommended by my friend at the dealership), who was quite helpful and knowledgeable. He said that with ~240k on it, it's possible that either a piston stuck internally, or an internal O-ring let go. If either of these items happen to be something that affects fluid flow or pressure, you'll get the "no go" symptom in all gears, despite a functional primary pump. He said that the time to tear down, diagnose, & reassemble is 12-17 hours. And, he doesn't do that anymore... he just orders a fresh rebuild from Peter Schmid (sp?) in SanFran, current price is about $1550 shipped to his shop door.

Soooooo, it looks like the tranny is officially dead. My BIL is mulling his options... option 1 is spend $1500+ for a rebuilt unit with warranty, which is about 5x more than he'd like to spend on a car that needs a whole new interior (kids & dogs, in case you were wondering.) Option 2 is spend $100 on a seal kit for the spare tranny (and 4 hours to re-seal it), install the spare trans, and hope it works. Option 3 is to install the spare trans in as-is, and hope it doesn't leak after sitting on the shelf for 10 years. (And that it works.)

He hasn't decided what to do yet. If it's the Peter Schmid route, I'm hoping they can tell him what was wrong with his old one sent back as a core. I'm really itching to know what the failed part is. If it were me, I'd toss the spare in there and cross my fingers. But neither of us relish the idea of another 8 hours of R&R if the spare leaks and/or doesn't shift right. D'oh. So much for an easy fix...

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Old 07-10-2007, 04:22 PM
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Well, my BIL decided to go the cheap route, and install the spare tranny as-is (remember, this unit had been in storage for approx 10 years). Lo and behold, it works great - no leaks (yet), and it shifts fine. I think I might take the failed tranny apart when I have some spare time (hah!) to see if I can find out what specific component failed.

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Old 07-21-2007, 01:12 AM
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so i was wondering if you had replaced the torque converter when you swapped transmisions because i was reading on the net about the converter going bad. I have the same problem with my car but unfortuneately i just put in a rebuild and didnt replace or take out the torque converter.

Stator clutch breakage: A very abrupt application of power can cause shock loading to the stator clutch, resulting in breakage. When this occurs, the stator will freely counter-rotate the pump and almost no power transmission will take place. In an automobile, the effect is similar to a severe case of transmission slippage and the vehicle is all but incapable of moving under its own power.

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