ALDA in a 92 300D 2.5 Turbo vs 85 300TD - PeachParts Mercedes-Benz Forum

#1 09-17-2004, 11:52 AM

Hello all,
I recently bought a 92 300D 2.5 Turbo, what a beautiful car.

Anyway my question is the car is a little sluggish off the line, but picks up quickly after about 3 seconds of so. Actually if you leave it floored it will screech the tires as it shifts into second gear...make sure your head rest is adjusted... We had a similar problem in our 85 300TD Wagon, but over came it with adjusting the ALDA, wow what difference that made.

I was hoping that the 92 had a similar ALDA adjustment I could make, but the engine configuration is quite different and I have no idea where the ALDA is; I think it could be underneath the manifold, but not sure.

Am I correct in assuming I can adjust the ALDA to help the sluggishness as with our 85 300TD? If so how?

Thanks for any help you can give...

SW · #2 09-17-2004, 07:29 PM

Your fuel injection pump (ALDA included) is hidden under the intake manifold. Do a search for posts on ALDA removal by gsxr. He's got some great info and pics to remove the ALDA on the 602, 603 engines.

#3 09-19-2004, 01:31 PM

Good advice I did the search and found the pictures. My confusion was that my ALDA looks differesnt. More bell and round that square like the ones gsxr has taken.

I looked at the vacuum lines and found on clogged from the intake manifold to the ALDA.

Upon further inspection I found the intake manifold was clogged...So I took it off to inspect and clean.

I was shocked the entire interior of the manifold was cover with about a with about a quarter inch of oil deposits....

I have rebuilt several gas engines, but never a diesel. I can't believe this is normal. Is it? I understand the oil system burps back into the intake, but this is a lot of build up. On inspection, the intake valves stems etc. were covered with this goo too. Is there some basic maintenance that helps prevent or minimize this?

By the way I cleaned the intake manifold (the best I could, Yuk!), adjusted the ALDA 1.25 turns CCW and the car runs better. Not as an impressive improvement as on my 85 300TD wagon but better than it was. I would recommend 2 full turns, and when I get back to it I will adjust my ALDA, right now I need to let my hands heal from getting dinged up from removing all those difficultly placed intake bolts and trying to find my tool we they slip behind the injection pump.

psfred · #4 09-19-2004, 03:00 PM

It's better to change the shim under the alda than to monkey with the screw, you can break the ALDA if you go two turns or more....

You really need a re-calibration of the pump, but all that really is means is replacing the shim with the correct one. I'm not sure if thicker or thinner is required, though!

Cleaning out the lines will make more difference.

You won't get the soot and glassy carbon buildup if you use synthetic oil, it stays fluid and carries all the soot into the intake and gets burned, unlike dino oil that will coke with the exhaust heat. My brother's 300SDL had only a very thin (1/16") layer of semifliud crud in it when we changed the valve cover last week, just wiped right out. There was some in the intake, too, but not much. Car has over 200,000 miles on it.

Peter

#5 09-19-2004, 07:21 PM

Hmmmm shims...I read gsxr earlier posting about shiming the ALDA seems like a trial and error process to get the right shiming...Where I can I purchases these shims, and mercedes shop?

Synthetic oil? Interesting most 123 car owners think synthetic is not worth it/ a bad... but you recommend it with a 124 car, huh?

psfred · #6 09-19-2004, 08:40 PM

Synthetic in the OM61x engines seems to get thick pretty fast, and collects more soot that the OM60x engines. I've not had any problems with synthetic in anything that doesn't leak, and my brother is using it in his 75 300D. Soot is probably the limiting factor, but several of the guys have done some oil testing, and at 6000 miles or so are still well below the soot limit for continued use.

Peter