Make sure that you do not break metal rings off of the plastic hoses attached to the banjo bolts.

Take the bolts out carefully and pull the hoses out of the switchover valve on the firewall. Spray carb cleaner into the hoses and into the switchover valve. Spray the cleaner into the bolts as well paying attention to the small holes that the rings cover to get the air pressure.

You will be surprised at the black crud that will come out.

The next thing you can do is 'tee' in a pressure gauge into the line going from the switchover valve to the ALDA and run it into the cabin so you can check the pressure as you drive. The turbo will not produce boost in the driveway.

__________________
"I have no convictions ... I blow with the wind, and the prevailing wind happens to be from Vichy"

Current
Monika '74 450 SL
BrownHilda '79 280SL
FoxyCleopatra '99 Chevy Suburban
Scarlett 2014 Jeep Cherokee
Krystal 2004 Volvo S60
Gone
'74 Jeep CJ5
'97 Jeep ZJ Laredo
Rudolf ‘86 300SDL
Bruno '81 300SD
Fritzi '84 BMW
'92 Subaru
'96 Impala SS
'71 Buick GS conv
'67 GTO conv
'63 Corvair conv
'57 Nomad

Are one of these the banjo bolt?
http://i493.photobucket.com/albums/rr291/mike_mangrum/82MB300D/Picture003.jpg

Is this the switchover valve?
http://i493.photobucket.com/albums/rr291/mike_mangrum/82MB300D/Picture004.jpg

Thanks,
Mike

No. Look at the rear end of the intake manifold.

Yes. The longer line should lead to the intake manifold banjo bolt.

This link will take away the guess work.

http://www.dieselgiant.com/mercedesaldaboostsystemservi.htm

__________________
On some nights I still believe that a car with the fuel gauge on empty can run about fifty more miles if you have the right music very loud on the radio. - HST

1983 300SD - 305000
1984 Toyota Landcruiser - 190000
1994 GMC Jimmy - 203000

https://media.giphy.com/media/X3nnss8PAj5aU/giphy.gif

Yes, that does take away the guess work.

Thanks!
Mike