High Idle, White Smoke, shifting funny, HELP!! 75 240D

[Ronkat81]

Hey Team,


I need all of your collective wisdom, I have looked over many posts about the high Idle trouble that often plagues the 240d's. A week ago I purchased a Dove Gray 1975 240D Mercedes. She is Clean. . . 3 dings that can be pulled out. in order to make her show room the carpet will have to be replaced although it isn't bad. One crack in the dashboard, other than that she is gorgeous!! I paid 1,850 for her. Pretty good? Anyway on to the tech questions. To get her home I drove her 140 miles. No problems at all. Now i did notice when I was driving home on the highway that everytime i took my foot off the gas that there would be a nice cloud of white smoke billowing out of the tailpipe. Also when I would stop the engine is idled up high. Now when you put it in gear it goes down and idles slowly. when you first crank it it idles as it should but as it warms up (3-4 minutes) it is raging. I know I probably need to adjust the valves I'm sure, but who knows? anyway i adjusted the idle on the air intake all the way closed. . still Idling high. I adjusted the idle control (the knob adjuster) all the way until it wasn't touching anymore. I also disconnected the linkage so that I could operate the air intake as I wished and still had no success. The only way to slow it down was to push in on the emergency stop and this would slow it. Then I unhooked the vaccume line from the intake and plugged it to see if it was getting too much air from a vaccume leak somewhere... Still a high Idle. Ok so that is problem one. Next is the shifting... I'm wondering if it is all related as when the all Mercedes do it starts in 2nd gear quickly shifts through 3 and into 4th. By the time i am running 15-20 mph I am already in 4th gear regardless of whether I am to the floor or not. I have noticed that she is losing a little bit of water (hopefully not a head gasket) but the only time she puffs the white smoke is at the high idle or when I release the gas when traveling at a good speed. Any Ideas??!?!