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  #1  
Old 10-15-2010, 07:22 PM
sjh sjh is offline
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Adjusting the ALDA in a 602 Engine

Greetings,

This is my first time generating a post so if I err please correct me.

I own a 1990 300D 2.5L Turbo-diesel in a w124 body. Wonderful car. My two prior MB diesels were non-turbos; an '81 300D (w123) & a '75 240D (w115). So when I got this car with its turbo I had more horsepower which I've put to use.

However my mileage was not what I expected (~25 city/hwy). The prior owner told me he had "tweaked" the ALDA to improve performance. However, he also sold the car as mechanically perfect to which I have put in motor mounts, injectors, cruise control amp and stalk, electric seat switch and replaced all vacuum actuators for heating/AC. So perhaps he was not as knowledgeable as he thought.

Regardless, I wanted to adjust my ALDA. Well life has changed since my '81 non-turbo and the ALDA is literally buried beneath the intake manifold.

I now show some pictures. Here's an overview of the engine with the intake manifold on top and the ALDA beneath -

Attached Thumbnails
Adjusting the ALDA in a 602 Engine-02a.jpg  

Last edited by sjh; 10-15-2010 at 08:02 PM.
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  #2  
Old 10-15-2010, 07:30 PM
sjh sjh is offline
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Adjusting the ALDA in a 602 Engine (02)

cont...

So I remove the vacuum line to the manifold, disconnect the sensor cable (don't know what the sensor does) and have this close-up of the ALDA. You'll note that I needed to deflect the metal lines going to injectors 4 and 5. In total I believe I bent the lines about 0.7 cm. You want to be careful and disturb the Lines as little as you can. I can now fit an open-end wrench into the ALDA. Doing so I loosen the lock-nut that is holding the set screw.

Time for picture #2 -
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Adjusting the ALDA in a 602 Engine-03.jpg  
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  #3  
Old 10-15-2010, 07:53 PM
sjh sjh is offline
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Adjusting the ALDA in a 602 Engine (03)

So now the nut is loose. I somehow need to get a screwdriver and an open-end wrench into that cramped space. After numerous efforts I decided I needed a different approach.

I took a small nylon wire wrap and put it on the fuel line on the other side of the intake manifold. Look at the picture, it'll make sense.

Now comes the most time consuming part of the process. I put the open-end wrench on the lock-nut but I approach it from the back-side, from the direction closest to the engine. This is cumbersome but I've done it many times.

Once the wrench is on the nut secure it with the wire wrap. I think the pictures tell the story. The last one is taken afer I have secured the wrench and you can see that everything is in place.
Attached Thumbnails
Adjusting the ALDA in a 602 Engine-04.jpg   Adjusting the ALDA in a 602 Engine-05.jpg   Adjusting the ALDA in a 602 Engine-06.jpg  
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  #4  
Old 10-15-2010, 08:01 PM
sjh sjh is offline
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Adjusting the ALDA in a 602 Engine (04)

Now that the nut is loose and secured it's time to take our screwdriver and turn the screw. For this task I went to our local Harbor Freight and bought P/N 92630 for less than $5.

However the stock bits are too long so I took the smallest regular bit, grabbed it with my vise-grips and ground off about half of the base. The photo shows a before and after.

Now I fit my angle screwdriver into the space. Work for a bit and get the blade in the slot. I'm able to turn the nut about 1 or 2 clicks on the ratchet so it takes me 5 or 6 (maybe more) moves with the tool before I have turned the screw a full turn.

I'm no expert on this but I make my ALDA adjustments using 1/2 or 1/4 turns. I've been able to increase my city/Hwy mileage to about 28 MPG.

Hope this helps.
Attached Thumbnails
Adjusting the ALDA in a 602 Engine-07.jpg   Adjusting the ALDA in a 602 Engine-08.jpg  
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  #5  
Old 10-16-2010, 09:53 AM
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Location: Milwaukee, WI
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Interesting approach, and thanks for sharing.

I just adjusted mine yesterday with great results. I removed the ALDA for adjusting which took about 5 minutes the 1st time (W201). The most time consuming part was ripping off the protective cap (virgin ALDA).

With the ALDA removed my particular car was overfueled and I didn't like the feel of my throttle being condensed into the first 1/4 of the pedal travel. With 1 full turn CCW it has come back to life and the pedal is nice and progressive. Note: Timing was checked, fuel filters replaced and vacuum system fully sorted and functional before the ALDA adjustment.

I was encouraged by the fact that my car was seemed so overfueled with the ALDA off, perhaps that means my IP has a long life ahead. Now Its time to dial in the bowden adjustment and modulator...

Was there a noticable loss in power with your CW adjustment? Was there a good deal of smoke on takeoff before your adjustment?
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1987 190D Turbo (W201 602)
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  #6  
Old 10-16-2010, 04:46 PM
sjh sjh is offline
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Mileage - etc

Greetings,

I'm not sure how I'd get my ALDA off without removing the manifold (again!) but perhaps I could.

My car was clearly running rich. Not heavy black smoke but the smell was a clear indicator.

I'd say I ended up turning it CW about 1 1/4 turns. I notice no lack of power and at least a 10% increase in mileage. I need to go through this tank to see exactly where I am now with the mileage.

The Good Dr.



Quote:
Originally Posted by camshaft190 View Post
Interesting approach, and thanks for sharing.

I just adjusted mine yesterday with great results. I removed the ALDA for adjusting which took about 5 minutes the 1st time (W201). The most time consuming part was ripping off the protective cap (virgin ALDA).

With the ALDA removed my particular car was overfueled and I didn't like the feel of my throttle being condensed into the first 1/4 of the pedal travel. With 1 full turn CCW it has come back to life and the pedal is nice and progressive. Note: Timing was checked, fuel filters replaced and vacuum system fully sorted and functional before the ALDA adjustment.

I was encouraged by the fact that my car was seemed so overfueled with the ALDA off, perhaps that means my IP has a long life ahead. Now Its time to dial in the bowden adjustment and modulator...

Was there a noticable loss in power with your CW adjustment? Was there a good deal of smoke on takeoff before your adjustment?
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  #7  
Old 10-16-2010, 07:31 PM
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I also have a 90 300d with the om602 and I was also thinking about tweaking my ALDA just a little. My car didn not have any boost when I bought it and I have a sneaking suspiscion that he turned it up to compinsate for the lack of power. Mine also is a little stinky if it idles in one spot for a while and at night I notice a lot of smoke while not under boost. Let me know how things work out for you.
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  #8  
Old 10-17-2010, 04:56 AM
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Quote:
Originally Posted by aka"thedude" View Post
I also have a 90 300d with the om602 and I was also thinking about tweaking my ALDA just a little. My car didn not have any boost when I bought it and I have a sneaking suspiscion that he turned it up to compinsate for the lack of power. Mine also is a little stinky if it idles in one spot for a while and at night I notice a lot of smoke while not under boost. Let me know how things work out for you.
Mine had the same problem when I bought it but it turned out to be that the turbo wasn't being engaged.

If your emissions control system has a vacuum leak it won't close the waste gate on the turbo giving you NO boost.

There's a fix on this forum somewhere.

Basically you completely remove all the emissions crap, plug the vacuum supply line to the emissions and install a pressure actuated waste gate actuator.

You then will have to tap the intake manifold, install a fitting and connect it to the new actuator.

Can you hear your turbo engage at about 1600-2000rpm?

What's your 0-60 time?

This is a good way to tell if you're turbo is working.

Before I fixed mine my times were 25-27 seconds....

After they are about 13 seconds with a slipping transmission.
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  #9  
Old 10-17-2010, 11:12 AM
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I already did the manual wastegate actuator convertion that was posted by GSXR. I am currently getting about 12 psi under full throttle and arounld 10 psi under normal acceleration and when climbing up steap hills. I just feel that when Im crusing for long periods of time and pushing little or no boost that the car smokes a little when it should not smoke at all.
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  #10  
Old 10-17-2010, 11:17 PM
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Quote:
Originally Posted by aka"thedude" View Post
I already did the manual wastegate actuator convertion that was posted by GSXR. I am currently getting about 12 psi under full throttle and arounld 10 psi under normal acceleration and when climbing up steap hills. I just feel that when Im crusing for long periods of time and pushing little or no boost that the car smokes a little when it should not smoke at all.
I see what you're getting at now.
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  #11  
Old 10-18-2010, 04:52 AM
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GSXR's Wastegate Swap (Illustrated,with measurments)

Wastegate actuator swap for OM602.962?
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  #12  
Old 06-11-2016, 12:06 PM
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Hello /world of wisdom and exp.
1987 300 sdl, 3.0 six cylinder w126 body style.
I own two of these one which is white takes off from dead stop and has plenty of power

NO SMOKE on either of the cars

The other car which is silver, identical year model etc, is like a turtle off the take off,,however no smoke at any speed, runs fairly well but not as strong as the other car any ideals,,
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  #13  
Old 06-11-2016, 12:15 PM
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HELP, Please

I own two identical 1987 Mercedes 300 SDL W126
Major issue with only one of the cars, very very weak on take off from dead stop

The other car has very crisp take off and plenty of pep while driving

The other is or seems much weaker,,,,,,,,,,,,,,,no blow by on either car, No smoke on either car

WEAKER CAR
Replaced vaccum lines, checked fuel flow, added monster electric fuel pump, no improvements.

Waste gate appear to be froze up ON BOTH CARS

WEAKER car next step is to remove turbo, however it looks like a beast. ALDA I do not think is the problems, reviewed all of your post which is great.

Question to all of you,,,,,,,,,,,should I rule out alda,
Should I move on the Turbo, fair shade tree mechanic
Biggest problem thanks of our Government, I am un employed and MONEY is very hard to come by.

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