If you are reaching the rev cut out point and only shifts into 3rd by backing off on the gas pedal to release the load, the K1 clutches could be slipping or a leak in the K1 accumulator, valve Body. The K1 applies for 3rd gear.

Do you have a shift into 4th gear. An oil pressure gauge would aid in diagnosing this problem. You can install the K1 spring Kit MB # 126 270 44 77 it’s about $12, it’s a quick and easy installation to do with the transmission in the car.

How is this spring kit installed ? I'm willing to try most anything. How do I check it with an oil pressure gauge ? I guess checking it first would be the most reasonable thing to do before attempting to install anything. What is the procedure for checking ? I am totally unfamiliar with this transmission, so any help with directions will be greatly appreciated.
Oh yes, I do have a shift into 4th normally, but I haven't tried to see if it will shift into 4th under full acceleration. I'll have to wait until the holiday traffic settles down and the speed cops are back to their normal routine before I try that. Your guidance in the checking procedure will be most helpful. I can begin there and see what happens. Thanks in advance.
Tom

C32AMG
I have tried to get in touch with you to find out how to use an oil pressure gauge to analize this problem, but have been unable to do so. Also, would like to know where the K-1 spring kit goes so I can try that. Can anyone else help ?

Some reading. http://www.peachparts.com/shopforum/search.php?searchid=891994
You'll need some sort of manual. The one mentioned in one of these posts isn't perfect, but it's a start.

__________________
The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

based on all your information this problem is almost certainly not mechanical but hydraulic.i suspect that the command valve for 3rd gear is sticking in the valve body and by running up to red line and then backing off on the throttle you drop down the pressure that is holding 2nd gear engaged which allows govenor pressure to overcome it and push home the command piston in the valve body for 3rd gear.this is not a diy job you will need the help of a skilled pro unless you elect to just buy a rebuilt valve body from mercedes and put it in.all your other gears work correctly except for third [and only then under full throttle] probably caused by minor defect in piston bore in valve body aggravated by very little use and lots of sitting around.

__________________
David S Poole
European Performance
Dallas, TX
4696880422

"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
http://www.w108.org/gallery/albums/A...1159.thumb.jpg

In your case I would install the K1 kit first.

To install the K1 spring kit, the pan must be removed, inspect the pan and filter for excessive metal or clutch material, if clean; Identify the K1 as illustrated in the picture it’s on the front of the transmission. Remove the four screws on the plate, and then remove the K1 accumulator with springs. Note the sequence of the parts. Assemble the new K1 kit exactly as the one removed, then install the assembly into the valve body. 1/2hour job.

Thats good to hear