83 300SD: Changed trans fluid/filter. Now won't go into gear.
 

This past Saturday I drained the transmission and torque converter, dropped the pan, and replaced the filter. The old fluid was somewhat dark (not bad, but darker than new) and there were some metal flakes present, but not terrible. Not enough to really concern me at the time, anyway. I did not notice any unusual odor.

I refilled the transmission with the engine at operating temperature, running in park, and filled it to the max line. Went for a test drive and everything felt fine. Shifts felt crisper than normal, and the car chirped the tires between 2nd and 3rd (never done that before!)

The car then sat for 48 hours. No leaks or anything else unusual developed.

Last night we got in to go to the grocery store, shifted into reverse, and nothing. Revved it up a little and I get a faint "clunk" from the rear end and the car moves forward slightly, then moves back again when I release the accelerator.

Shifting into forward gears produces the same result. Faint clunk from the rear, and the car won't go anywhere at all, regardless of RPM. But in forward gear, if I wind it up past about 2000 RPM, the speedometer starts to jump up to about 40 mph, then back to zero when I let off the accelerator.

I siphoned about half a quart of ATF out of the dipstick hole and poured a bottle of Trans-X high-mileage in, then ran the engine until it was at operating temperature again, and verified proper trans fluid level in park.

The car still won't go anywhere in any gear.

So ... it seems amazing to me, but did I break something simply by changing the fluid and filter?

I've got a "spare" transmission in a parts 300SD that I'm consdering dropping and putting in this car. It's got ~80k fewer miles on it and seems to work fine, but I haven't had a look at the pan.

Is there anything more I can do to troubleshoot before I just drop the transmission?

How many miles had it been since it was last changed? How many miles are on the unit? You are checking it at temperature, idling in park?

I have seen them go bad after a fluid/filter change. Which fluid did you use?

No way of knowing how long since the last change. I believe it's the original transmission, so 293k miles.

Yep, running, in park, temp gauge about 90 C.

I used Wal-Mart SuperTech Dex III /Merc.

My only thought is that maybe you used the wrong filter. There are 2 very similar ones for the diesel tannys. Maybe somehow the pick up is blocked? I'd drop the pan and take a look.

well, the car's supposed to have fluid changes at every 30K, so likely the first 100K or so were dealer maintained, and got the recommended changes, but after that, not so much, likely it's had over 200K on it since fluid was take care of.
your transmission is acting oddly to be sure, my guess is the pump or a shaft bit the dust on one of those CHIRPS... fresh fluid can clean residue, and soften or harden seals, and o-rings, causing things to act differently than before. also, it's possible that you knocked off the vacuum line, and caused hard shifts.
I'd swap tranny's and hope for the best on it.

One other thing. I've tried cheap arse fluid in a older MB application one time and it caused all kinds of problems.

I vaguely remember some one having the Yoke on the Out Put Shaft come loose or being stripped out with similar symptoms.
If the Speedo Needle was moving I am gurssing there must have been Transmission movement up to that point inside of the Transmission.

While you are under there checking to see if the Filter you installed is OK see if there is anything else in the Drive Train disconnected.

... wow. good call D911

Ok -- I got under the car this evening and looked at both flex discs; they're both intact. I didn't even see any cracks in either one.

I verified the vacuum line is connected to the transmission.

I started up the car with the rear wheels up on jackstands. When I put it in reverse, the wheels turn in reverse. When I put it in drive, the wheels turn forward. But nothing when the wheels are on the ground and under load.

Driveshaft looks intact and normal.

I dropped the pan and looked at the fluid (which only has about 5 miles on it) and compared the filter I installed to the one I took off the car.

Filters are identical.

The fluid has metal particles and again looks burned -- has black swirls throughout -- but does not smell bad.

After replacing the filter and refilling with ATF, still the car will not go anywhere.

Hm this doesnt sound good.. Metal particles are never a good sign.

I was going to say perhaps B2 piston but with reverse being out as well that seems unlikely.

You could always take the cover off and inspect the piston and if its OK just reinstall it..

I suspect vstech is right, the pump or a shaft bit the dust.

Answer
 

This issue is becoming more common.
Bad 722.xxx-transmission output flange spinning on shaft

http://www.peachparts.com/shopforum/diesel-discussion/301813-transmission-problem-fix.html

http://www.peachparts.com/shopforum/mercedes-parts-reference-library/301849-output-flange-722-xxx-transmission.html


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This looks like it just might be where the problem lies. I'll have a look at it tonight. Thanks.

FYI
 

^^ Yes. double check ( even if mentally ) how much fluid you put in it. I stupidly changed the filter and TC fluid on the 380SL and forgot the owner's manual. I happened to have a W123 Haynes manual (we were fixing his 240D) and it read something like 5 quarts, but it didn't specify if that was with or w/o the TC. It wouldn't move until I kept dumping fluid in it. Finally I got home and read the manual and I was pissed at myself.

The other possibilities that come to mind are bad front pump or torque converter.

I wonder if I could have my wife in the car with it in reverse, and me slowly pouring fluid into the dipstick hole, and see if there's some magic amount that will cause the car to move? I've verified via the dipstick that the level is where it's supposed to be, but I couldn't tell you how many quarts that is -- I just relied upon the dipstick to tell me where it should be.

Is it possible for the dipstick to read at maximum and the torque converter to still not be full of fluid?