I adjusted the alda and got real good power off the line. A week later I decided to back the adjustment off just a little bit(less than 1/4 turn). The power off the line dropped off a lot. I adjusted the alda back up and nothing happened. I then adjusted it all the way up, still no improvment. Next I hooked up a hand pump and gauge to the alda an it holds pressure at all points from 3 to 15 psi.
I made sure all lines and fittings from the intake manifold to the alda are clear.
First do you have to remove the alda to test it because the entire system holds pressure or can you test in place? What else could be keeping me from being able to readjust the response back to comming on quicker?

Please, any and all help will be greatly appreciated.

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1983 300SD
200000miles

The manifold banjo, tube or cross over valve could be plugged = not passing pressure to ALDA, this can happen very sudden.

You may also have an air leak on the suction side of fuel system = cracked hose or O ring = very sudden.

How long since fuel filters where replaced = possible plugged filter.

You can test it in place.
Start engine.
Have assistant raise RPM to 1500.
Apply pressure to ALDA slow.
You will hear RPM change + possible smoke = excess fuel.
When you hear change, pull hose off ALDA, should hear sudden drop in RPM and/or smoke.

__________________
ASE Master Mechanic
asemastermechanic@juno.com

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
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Technical Quality Auditor.
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1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

https://www.boldegoist.com/

I just changed the main fuel filter just incase. I'll try testing as you suggested tomarrow. Thanks very much

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1983 300SD
200000miles

Haven't I read on here before that you can break off something inside the alda when adjustment screw reaches a certain mechanical limit????
This coming from someone with a non-turbo.

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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

Easy to break if you go too far.

I was very careful when I adjusted the alda although if by doing the above tests I still don't get results I will take the alda top apart and have a look.

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1983 300SD
200000miles

OK I went out to do the above testing and first of all it was very hard to get the engine to hold at 1500 RPM but we finally got it. I added pressure and there was no change so I checked all test equip. and all ok. Reran test and same thing, adding pressure has no effect. Is it possable for the alda to be bad and still hold pressure? Any other suggestions? I need help.
Thanks in advance for any and all ideas.

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1983 300SD
200000miles

Remove ALDA, check for free motion of pin under it.
Read this thread:
http://www.peachparts.com/shopforum/showthread.php?t=111032&highlight=alda

Yes, the ALDA can be junk, I have seen inside one turned to corroded trash = very rare.

I'll try that tonight
Thanks very much for your help. I'm still new to a lot of this stuff.
I work on a lot of machinery every day at work so mechanical things are usually not a mystery but this is something entirely different.

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1983 300SD
200000miles

I finally got home before dark so I removed the alda and checked the pin under it. It moves easy. I then looked at the under side of the alda and found the cup that the pin sits in flopping around loose. Does this mean that it's broken? All the pictures I've seen make it look like this is not right. The strange thing is that it holds pressure but that could just mean that the upper part of this bellows is in tact.
Does any one have a good alda that they want to sell.
Thanks as always for any and all advice.
It sure would be interesting if we could have a country wide get together.

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1983 300SD
200000miles

How much does the cup move around? I have an ALDA in my hand right now and the cup moves a few millimeters each direction.

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Adam Lumsden
(83) 300D
Vice-President of the MBCA International Stars Section

The cup flops around like it's not attached to anything. I tried to take it apart but with out a vise I can't get a good grip on it. I'll take it to work and use the vise and impact driver there next week.

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1983 300SD
200000miles

ALDA R&R disassembly, cleaning.
http://www.peachparts.com/shopforum/showthread.php?t=111032&highlight=alda

This is an update to my power problem as related to the alda adjustment. I bought a new banjo fitting and line in the hope that it might help. I removed the old fitting and line and blew it out with compressed air. I also checked it for any cracks. Air went through fine and no cracks. I tried blowing through the new fitting and line and found that although air went through the old one ok it wasn't at the same volume as the new one. I cut of the line on the old fitting and found that it was partially restricted but not all the way. I installed the new set and the lost power is back. I think when I first adjusted the alda some carbon got blown into the fitting, but not enough to stop it up completely. I know others have had this problem. I hope this helps.

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1983 300SD
200000miles

Thanks for the update Phil. I encountered this same problem recently. Have you removed and cleaned the intake? I believe this is the next step I will be taking to minimize this from happening again. Especially since disabling the EGR "for test purposes".

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )