Long time listener, first time caller. 1985 300D turbo 257k on the non-working odometer.

I was re-adjusting my ALDA last night and the screw top broke(half of the flat). I tightened up the locknut. Tried to drive it to work today and no turbo(how do people drive the non-turbo models?).

Is there anyway to bypass the ALDA? Should I try to get the screw to regrab diaphram tread and start adjustment over again? I would like to bypass and get full signal if possible.

Thanks in advance,
Jason

You may have put the cart before the horse. Adjusting the alda usually helps off-the-line performance before the turbo kicks in. Your problem sounds more like a blockage in the boost line, either at the banjo bolt on the back of the intake manifold or the boost over-pressure valve on the firewall. Or, if it has really gone far, at the banjo bolt on the alda itself.

(My system had been bypassed direct to the alda and the entire system, alda and all, had to be removed and cleaned. Be sure to relube the alda if this is necessary.)

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Sam

84 300SD 350K+ miles ( Blue Belle )

I was having no problem with power before - just couldn't leave well enough alone. I had adjusted alda out 1 and a half turns. Tried to go one quarter more and now no signal.

It is not a blockage - drove home fine. Cranked this morning and engine took forever to rev up. Parked it and drove my truck to work.

If a maxed out screw delivers full signal - can I just bypass the ALDA unit and operate off that full signal? I will still have the overboost protection of unit on firewall and wastegate.

When you broke off that screw, you damaged the guts of the ALDA.

Inside, there are two sealed capsules with a calibrated pressure inside each. The screw is basicly a plug/cap to one of theose capsules. Now that it's lost it's calibrated pressure, it won't work anymore.

All you can do to fix it is replace the ALDA (Can't be bought new from MB). A parts yard or a fellow forum member are about your only reasonably priced sources.

When folks here have cautioned about turning one too far and breaking it. Now I understand. If someone applys too heavy of a hand and the alda is at its limit, the aneroid may rupture. Can it be jury-rigged? Possibly, but I have not read here where this has been attempted. It would have to be taken apart and see if it could be resealed. Here is some info if you want to attempt it:http://engine.articles.mbz.org/diesel/alda/

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Sam

84 300SD 350K+ miles ( Blue Belle )

The ALDA is for fuel enrichment purposes. The turbo tells it what to do. So, in effect, what you have is no fuel enrichment on account of a busted ALDA. Bypassing the ALDA will not help, as the injection pump has no way of transposing the turbo boost signal since the ALDA is broken. Think of it as a situation where the IP needs to understand the turbo, yet the two speak different languages. The ALDA is the translator. You need that part in working condition. Get a new one off eBay.
I think people bank entirely too much on ALDA adjustment(or overadjustment as the case may be) being the cure-all for sluggish performance. In my experience it has been other various and sundry items that needed addressing to overcome the power issues with my car. Once I changed fuel filters, adjusted the valves, adjusted the turbo wastegate, and changed the ALDA hoses and overboost solenoid I found adjusting the ALDA itself didn't do much for me.

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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)

You can also take the ALDA apart and remove the capsules. This is the only way to "bypass" it.

which is what im doing.. gotta control the mesquito population some how

the ALDA can be eliminated from the equasion all together! Ask ForcedInduction! I may try the same thing!

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RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

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FACEBOOK: PANZER450

UPDATE - Running the empty ALDA "dustcap" now and loving it. Why didn't I break that earlier? Smokes only under full throttle, and "off the line" like I didn't know was possible.

Thanks for the help -
Jason

I'm glad that I'm not the only one who enjoys it.