Having never removed the ALDA from my 83 300SD.

Can I spin it to remove it ?
Counter Clockwise ? Like unscrewing a bottle cap ?

I can get a wrench on the nut (26mm, 1 1/16" , or crescent)
get a little room to move but cannot budge the nut underneath the ALDA
square unit. Not too suprised, everything on this car is tightened to
the max.

I did a vacuum test and it leaks.
I did a pressure test with a bicycle pump and a fuel pressure gauge
and it leaks down and it will not hold air.

When the boost line is disconnected I get no difference in power.
Cleaned out the banjo bolt at the manifold and the line to aneroid.
I now have a boost gauge installed after the aneroid before the
ALDA and get a nice consistent boost of 9 to 10 PSI under load
at speed.

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80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250

1984 300d Turbo
Use A Big Wrench On The Alda, Or A Big Tool To Hold The Alda This Size At The Auto Store And Mm Wrench Under The Alda That Turns Cw Nut To Remove. GET A METIC O-RING KIT FROM JCWHITNEY.COM OR **************.COM REMOVE 4 SCREWS MAY HAVE TO DRILL 2 EA OUT AND
REPLACE WITH NEW SCREWS ON MY ALDA IT WAS THE SMALL O RING

1984 300d Turbo
Use A Big Wrench On The Alda, Or A Big Tool To Hold The Alda This Size At The Auto Store And Mm Wrench Under The Alda That Turns Cw Nut To Remove Turn The Alda Ccw

Tomorrow I will take off injector lines to make this a little easier
and get something to hold the ALDA while I spin the nut CW.

__________________
80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250

Be very careful when removing it. I have to just loosen the 4 screws and rotate the whole assemble to gain access to the internals of the pump when removing the shutoff valve. I was not removing the ALDA though.

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1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

This ALDA unit was really really tight.
Looked like someone used thread compound.

Anyway, now that it is off and threads clean I can work on it.

On the bench I pressurized it and the internal part pushes OUT
when pressurized. I think is is supposed to suck in.

__________________
80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250