I am trying to get my 300D to run a bit better. I think it is a little sluggish. It came with an aftermarket boost gauge. I am only getting 4-5 psi max at full throttle. I took it to a mechanic who works on a lot of diesel trucks but never touched one of these. His first concern was why the gauge was hooked up the way it is. He doesn't know what kind of part it is hooked into so I am turning to you for advise. If you look you will see what looks to be a relay of some sort with the 2 blue hoses going into it. 1st, what is that & 2nd, is that the proper way to hook up a boost gauge on these cars? We want to see if we are getting an accurate reading from the gauge before moving on to something else. Thanks for the advise.

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well, your picture does not cover the entire setup. also, where the boost hose attaches, looks like the Tee is open on one side.
that relay is the overboost protection, yes it's normal. looks like the original got damaged, and someone replaced the line. nice job.
get a wider pic posted here, and we can commend on weather or not it's connected properly.
is that tee open? it should not be.

you know it will only build boost pressure under load right? only on the road with hard acceleration.
not at idle/ sitting in park.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

after talking with you, I figure in addition to the goofy boost gauge connection, the alda is damaged.
others on here can assist you with any tips for alda removal, but it should be 22mm and 24mm open end wrenches to loosen it, and remove.
report back when it's off and see what the boost does, and how the power feels.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

The rain is starting to slow down so as soon as it stops, I will be out thier with my wrenches and hoping that works.

Get ride of the ALDA and plug the line going from the over boost to the ALDA.

The way to get the ALDA off, if it does not come off easily, is to have someone hold the top "saucer" portion of the ALDA while you or another person tap, via hammer, the locking nut with a punch or screwdriver. The entire process should take about 10 minutes. 2 if you have done it before.

I've had some come off easily with a crescent wrench and others the way above. Once it's gone you will notice a good improvement of low end power.