Turning the ALDA screw won't raise your boost. You need to get into the wastegate on the turbo for that.

__________________
1982 300CD Petrol/Black Leather

I can't recall, but I didn't have any issues turning the screw, the lock nut holds it in place.

I agree with 1983…, altering the screw will increase fuel flow, not boost. Once there is sufficient fuel to match the air, you get optimal performance.

BTW, you must be going extremely fast in that video, you're upside down!

__________________
83 SD

84 CD

What does turning the ALDA screw CCW do? I thought it gives it more fuel? I am not getting any smoke when flooredd, i.e. not enough fuel, therefore not enough boost.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

I would estimate a half gallon. A quick google search pretty much confirms that no one really knows. Numbers are all over the place (kind of like Craigs List mileage claims)

I don't think you had a boost problem at all. Your "boost problem" was taking the reading downstream of the clogged overboost solenoid. You had a fueling problem, in that the ALDA never got the signal that boost was being created to be able to add more fuel, hence lower power.

But your second statement does not make any sense. Boost has very little to do with fuel economy, but it has everything to do with power. A NA 617.910 puts out 80 hp while a turbo 617.952 puts out 125 hp. It does this with the same cylinder volume by increasing the effective air charge by introducing the air under pressure, 10 or so psi above ambient. You may gain just a bit of efficiency due to thermal efficiency, but negligible. The one place where you were hurting mileage some was spinning the turbo but not adding fuel to take advantage of it - just adding back pressure for no reason.

I think you're in pretty good shape with what you've got now.

__________________
Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

You are correct, turning the screw ccw will increase fuel flow.

You don't have excess fuel, no smoke when floored, back it out a bit at a time until you do.

Turboed engines need a balance between boost and fuel.

Attached Thumbnails

 

__________________
83 SD

84 CD

Well, I kept increasing turns on the screw and currently at 2 turns ccw and still can't get any black smoke. How many turns can it go before the screw falls out? Maybe it is jammed from lack of movement (switchover valve was mostly blocked for a long time possibly). Should I remove the ALDA temporarily? That should give it max fuel correct?

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

The screw wont fall out, dont force it... Shimming the ALDA is the best way to go imo. You were happy before and happier now, I wouldnt go chasing dragons. Look where it got me. Paranoid. delusional. power hungry.

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

You've gone into politics ?

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

Do you feel any difference in performance? Assuming your car is producing boost, you should be feeling a major improvement at 2 turns.

If not, and you have boost from the turbo, then it sounds like your ALDA adjuster is broken. Back in the day, the ex-Mercedes dealer tech on the old list I was on said it would happen to about one in twenty cars when the screw was turned.

BTW, when people say "black smoke" the actual standard is that you should just be able to see black smoke under hard acceleration in daytime. We're not talking naval exercise smoke here....

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

No difference in performance or smoke with 2 turns ccw, boost stayed at 10 psi max, that's why I think it's stuck. Maybe it's plugged with carbon and jammed? Sent your clear nylon banjo line yesterday btw.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

No advice from experience I can offer on how to proceed, just a story.

I had an SD where I did 1/2 turn, made some difference... went back for another go, all of a sudden there was no resistance from the screw. Nothing more happened in terms of performance. I just lived with what I got out of it. The motor was pooched anyway.

Thanks for the update on the line.

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

The boost is going to stay at 10 psi no matter which way you turn the ALDA screw. You are just giving more boost fuel, but not affecting the boost pressure.

Try screwing the ALDA screw all the way in and see where it starts inhibiting performance, the adjust until you get no more benefit. Or, some people remove their ALDA altogether.

__________________
1982 300CD Petrol/Black Leather

Is the ARV working? Mine had no boost cruising below 65. I blocked the line to the ARV and have boost at low rpm now.

It helped the mileage a lot too.

__________________
85 Merc 300D - Unwinding 31 years of wear
86 VW TD
Mahindra Diesel
Iseki Diesel

In 2007 I didn't own a diesel.

why don't you install the boost gauge in the car more permanently. Then take out the alda. Is the EGR leaking?

Mileage isn't affected much by peak boost pressure. It is more affected by the boost that the car has at cruise.

__________________
85 Merc 300D - Unwinding 31 years of wear
86 VW TD
Mahindra Diesel
Iseki Diesel

In 2007 I didn't own a diesel.

This 85 is pristine and unmolested, the engine has never been messed with either. I don't want to drill or cut into anything to install a boost gauge. It is just instrumentation to get the car to produce better mpg. No plans for a permanent boost gauge either. I disabled the EGR with a BB, have not touched the ARV yet. What bothers me is after removing the ALDA plastic seal and turning the screw 2 turns ccw, it did not produce any smoke, leading me to think it is stuck in one position.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked