Ok let me give you thr run down. This is my very first MB. Its a 1983 300D TD. I aquired this car from G/f parents. I have hardly any Idea the way this car works. I am a tech for Oldsmobile and have some knowlegdge. Ok this is the problem. When I put the car in drive, it just revs up till about ohhh 3000 rpm before
it will engage in first. Now this car has been sitting up for like two years because of the tranny. It was a factory reman. tranny with not very many miles on it. After it revs up I let go of the throttle a little and it will engage to 1st gear with a hard shift. ALl other gears work perfectly. Fluid level is ok, and just today I dropped the tranny pan and found the inside to look perfect. No metal shavings or any signs of
metal peices. SO i HOPE this is a good sign. It will work in reverse good also. Now I was told something about adj. the Modulator valve. SO I was going to do this today, but could not find the Mod. valve. I was told it was on the right side of the tranny with a red cover. I seen no red cover. I am not sure what kind of tranny this is, but the pan has 6 bolts. Can a Vacuum leak cause this, and if so how could it just effect the 1st gear and not the rest? Oh and one other thing, This is this wire that goes to a rubber boot looking thing at the right rear of the tranny? what is that? the wire was broken, so I spliced it back with the other wire?!?!?!?!? I hope someone can help me. I do not hve the money for a tranny, so do not tell me I need this! lol. OH and I did check some of the vacuum lines while the motor <5cyl> was running and there was no vacuum going though the lines I checked. There is a check valve at the brake booster that is cracked and has been glued and while checking for vaccun I cracked is and tapped it up just to get home. I know this is a long post, but I really need the help!!!!!!!!!!!!!!!!
Thanks
Stephen

Stephen - do a search for this exact problem here on the site. Trannys are the #2 most-requested topic. You'll find all kinds of ideas about what to look for, where adjustments and parts are located, etc etc.

I did the search and was unable to find any help, well actually I got tires of reading. I did adj. the mod. valve, but the only difference that I noticed was how hard it shifted. I adj. till when I was in 1st gear to 2nd gear, the rear tires spun a bit, so I adj. less one notch where it was set before. No difference. I did see a post where I should put a vacumm line to the Mod. valve and use a vacumm pump, I did this and when I let go of the vacumm I seemed to shift to 1st. or 2nd???? not sure. What else could cause me not to engage in 1.st gear?? Tranny I found out has serveral thoudand miles on it!!?? thanks
Stephen