ALDA - Adjustment screw - PeachParts Mercedes-Benz Forum

#1 09-12-2003, 01:30 AM

Can I adjust this type of ALDA? See photo. If so, where is the screw, that everyone is talking about that can improve the take-off from idle, located? Thanks.

jbaj007 · #2 09-12-2003, 01:59 AM

The screw is under that metal "can" right there on top of the ALDA. Peel off the can (rather agressively) and it's underneath. Yours has NEVER been adjusted, we can assume, so you may get a very nice result after 19 yrs. of having a "spinster" ALDA.

#3 09-12-2003, 03:33 AM

jbah007:

Using a pair of pliers, I tried to twist, turn and pull to no avail. There's no feeling of movement. If I force it, I'm afraid that I will destroy the "can" and the procedure will be irreversible. Is this okay? Can I just pull out the black cover?

JerryBro · #4 09-12-2003, 06:38 AM

The center of the can is a plastic cap. Stick a small thin screwdriver between the cap and the can and you can pry the cap out. Once out, you'll see a slotted screw held in place by a locknut. The locknut can be loosened with a 10mm thinwall socket (Craftsman 1/4 drive is perfect) allowing you to adjust the screw.

Jerry

#5 09-12-2003, 01:44 PM

Here is how I did it (It works). Use a screwdriver and remove the center plastic cap. Use a pair of wire cutters and cut the "can's" wall as far down past the nut as you can. Use a set of pliers and twist the can off its base. This way you can use a wrench and screwdriver combo to make sure your adjustment does not move while you tighten the nut.

#6 09-12-2003, 07:48 PM

Thank you all!

I have mutilated the "can" using tin snips, peeled it off like a banana, etc.. and exposed the ALDA adjusting screw. There it is a "spinster" of 19 years, said jbaj007.

188,187 km. - turned 1/4 ccw - no noticeable difference on take-off

188,194 km. - turned +1/4 ccw - noticeable difference on take-off

188,200 km. - turned +1/4 ccw - I will let you know but convinced that I will set it here at total = 3/4 turn ccw.

Joe Blowe · #7 09-12-2003, 07:54 PM

Hey 84W123DT,

Is this the first time you've posted a picture of your ride? Pretty damn nice...

#8 09-13-2003, 01:01 AM

After 19 years of suppressed acceleration and thanks to you guys at Shop Forum, I now have a pretty peppy born again Diesel. Happy! Happy! Happy!

I’ve set the ALDA adjusting screw 1 full turn (360*) ccw, disabled the EGR and WOW!

I welcome the sacrifice of diesel consumption, if any, for the performance! I was so happy that I took my son out for a late evening drive (he should have been in bed!) and gave the car a good Italian tune up (to 150kph @ 4,000 rpm) purrrrrrrrr!.

Thanks Joe Blowe for the compliment of Smokeless.

lietuviai · #9 09-17-2003, 10:23 PM

I made the adjustment ( 1 whole turn CCW) on my ALDA a couple of days ago and I have also noticed quite an improvement in acceleration off the line. I also plugged the vaccum line on the EGR as well. I would recommend this adjustment to anyone who has not had it done. It was very easy to access the adjustment bolt by simply removing the soft plastic plug with a small flat tipped screw-driver that covers it. I used a thin walled 10mm 1/4 drive socket to loosen the nut and the same screw driver to turn the slotted bolt to make the adjustment. It couldn't be any easier!
One thing though, how many turns would be too much?

mjstef · #10 09-17-2003, 11:11 PM

Does an 81 300sd have this????

jbaj007 · #11 09-18-2003, 12:54 AM

yep

jhal · #12 09-18-2003, 08:24 PM

I wouldn't go more than one turn CCW. Putting too much fuel in your engine can result in combustion temps going too high. Not good if you want your engine to last a long time. Unlike gas engines, diesels run hotter as more fuel is injected. If your temp gauge is rising when you are running hard, it could be a sign of too much fuel. The only real way to tell is with an exhaust gas temp gauge. There has been a lot of discussion on this very subject in this forum. Try looking up EGT or ALDA or even BOOST in the search box. Usually, when you are producing more smoke than power, is when you should back off of the adjustment a little.

lietuviai · #13 09-18-2003, 08:48 PM

I did notice a little more smoke in my rear view mirror the other morning. Fortunately the car isn't running any hotter. I'll see what backing off a 1/4 turn might do.
Thanks jhal!

#14 09-18-2003, 09:06 PM

Where is a good place to buy an EGT gauge? Places like jeggs want $120+ for a gauge and sensor. I konw tempreture drops very fast in the exhaust system, where would the best place to put the sensor be? Next to a port, in the collecting joint before the turbo, immeadiatly after the turbo, etc.?

jhal · #15 09-18-2003, 09:27 PM

I'm not sure on a good place to buy an EGT gauge and sensor. They are all fairly expensive because of the high temperatures they are exposed to and measure. Usually within a couple of inches of the turbo outlet is acceptable. The closer the better. Some people install them before the turbo in the exhaust manifold. I think on the 617's it is easiest to install a probe fitting into the exhaust pipe at the turbo outlet. I want to do this to my car, but haven't yet. Time, money, etc.