300sdl tranny question

[NC300SDL]

Hi guys,
Just recently joined the forum. Have been reading it for about 3 months. Purchased a 1987 300SDL in mid Feb. Read a lot before making purchase and of course quite a bit more since then. The car had a new head installed within the last 12000 miles. Body and interior are in pretty good shape. Odometer is showing 134xxx miles, but not sure if this is accurate. A few days ago, I had driven about 40 miles and all was good with trans. I then drove on the freeway for about a 65 mile trip(have put about 3000 miles on car in last 3 months). I stopped by my house to get some tools on the way back to the office. Upon leaving the house, I drove about 2 miles and stopped at a light. After I started driving again the car would not shift out of second gear. 25mph at 3500rpm. Pulled over, checked fluid, ok. Tried driving again, but still no shift. I drove back home, changed cars and tried it again when I got home from work, still no shift. Reverse works fine. From what I have read I think it may be a B-2 piston problem. Do you think I am on the right track? Have gasket and filter but not time to change yet. Thanks in advance, love the forum.

[Brian Carlton]

Welcome to the forum.

Under the accelerator pedal is a switch. It's the kickdown switch. First, make sure that the switch is not sticking down from the carpet. Then, if it's OK, unplug the switch and drive it again.

Report back.

[NC300SDL]

Pulled carpet, checked switch. Operation seems normal. Drove car, no change. Disconnected switch, drove car, still no change. I am open to any other suggestions. Thanks

[Brian Carlton]

Originally Posted by NC300SDL

Pulled carpet, checked switch. Operation seems normal. Drove car, no change. Disconnected switch, drove car, still no change. I am open to any other suggestions. Thanks

There is a cable that extends from the rack linkage near the back of the IP to the transmission. This delays the shifts when the engine demands are high.

If the cable is bound up and won't fully retract, the shifts will be delayed at all times.

Find the cable and make sure that it moves the arm properly at the transmission end when the rack is opened. Of greater importance, is to be sure that it returns the arm when the rack is closed.

[NC300SDL]

Checked cable under hood, seems to be okay. Moves back and forth with no binding. Was not able to get under car and check at transmission due to other obligations. Will probably be Wed. night before I can do this. I did re-check the trans fluid though and found it to be low. It was at the first mark below full. I added fluid and took it for a short drive around the block. Still no shifting. Thanks for your help so far and I will report back after I can get under the car.

[Brian Carlton]

Originally Posted by NC300SDL

Checked cable under hood, seems to be okay. Moves back and forth with no binding. Was not able to get under car and check at transmission due to other obligations. Will probably be Wed. night before I can do this. I did re-check the trans fluid though and found it to be low. It was at the first mark below full. I added fluid and took it for a short drive around the block. Still no shifting. Thanks for your help so far and I will report back after I can get under the car.

When you check it, spend some time and be sure the arm is returning fully to the stop. You may not know where the stop is and might have to disconnect the cable to be sure of this.

Don't just take a fast look. It's rather important now, because we're almost out of options if this is not the issue.

[NC300SDL]

Brian,
Finally got under car today. Let me see if I understand you correctly. The cable that you are referring to goes from the accelerator linkage to the transmission. Right so far? If so, I do not see an arm. This cable that I am looking at goes into the top of a plastic piece, which is on the right side of the transmission. Plastic piece is maybe 2-21/2 inches long and is close to the transmission cooler line. That is the only thing I see on that side. On the left is a vacumn line, which is connected, as well as the gear selector linkage, and a wire that looks like it goes into the body of the car and another round black thing with a wire going into that. Am I missing something? If I have the right cable then I do not see any binding.

[Brian Carlton]

I must admit that I've not checked it out on the SDL and it may not have an arm. But, it's important to be sure that the cable moves without any binding and that it returns fully to it's "stop" position when the rack is closed.