300sd ALDA

[tkelley]

This is my first post on this forum and I would like to thank everyone for the help this forum has been in the past. I have been slowly repairing a 1980 300sd for my son. Have overcome most of the standard problems. However I tried to adjust the ALDA and found that may unit will only move about one turn each way. ( the engine in the care is a 1985 if this makes a difference). Is this normal or do I need a new ALDA.

[dieseldiehard]

Something is wrong. If you loosen the locknut, the slotted shaft should turn easily CCW. Do not tighten it Clockwise, that may ruin the Alda! You should always write down (or remember ) how far it is rotated off "normal" - one to two turns CCW should be more than enough to make the engine run substantially stronger than factory setting, and it will also start blowing smoke more than normal too!
Dieseldiehard
1971 220 (gas) 4-spd manual 104041
1979 300TD w/ ’85 turbo engine 289560
1983 300D 237490
1985 300TD 206150

[gsxr]

That doesn't sound right to me either. Whatever you do, DON'T force the screw in either direction. It should turn with very little effort once the locknut is loosened. Forcing it can break the aneroid capsule inside, which will effectively destroy the ALDA. If that happens, you need to get a used one (new ones are megabucks from Bosch). There are photos of what the ALDA internals look like at this URL:

http://www.meimann.com/images/mercedes/OM603_injection/

If it leaks (won't hold pressure or leaks down fast), a new shaft seal effectively "rebuilds" them for under ten bucks (if you can get the seal from Bosch). I've rebuilt two now and it worked great.