I've read thru several of the ALDA threads and tried adjusting mine in my 84 300SD. The cap had been removed previously by??? I was able to back the screw out another couple of turns till it would not turn any more. The low end power was better but there was no smoke under heavy load. The only black smoke tha can be seen is when you blip the throttle as the rpm snaps back there is a little puff of black.

As well I've read that my 0-60mph times should be close to 11s. Before I adjusted the ALDA they were high 17s. After, despite the better response in the low range, the times were still high 17s. New fuel filters and a rebuilt lift pump as well as a new idle rack bolt.

Any ideas from the experts?

An 84 300SD in perfect tune will have an honest (no cheating) 0-60 in 15-16 seconds, maybe as low as 14 in ideal conditions.

See if the ALDA holds vacuum, might be bad.

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles

No. Never use vacuum to test it you'll, just be wasting your time. It works by positive air pressure and the turbo has an infinite supply of it to work with.

True, it is a positive pressure that extends the rod. However, if the diaphragm is broken, it will not hold vacuum.

I've had it happen to me.

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles

I'll try the vacuum test of the daiphram, thanks. I'm also wondering if the fuel release? valve in the lift pump might be stuck. I'll try get it out and clean the ball and spring. No fuel, no smoke???

I just had one of the old style ALDA’s (one’s with screws) apart to refurbish it, it has two bellows/ diaphragms that are sealed (like an unopened can), these are house in a chamber that is sealed, but with one opening going to your pressure line, and where they leak is around the seal, that the piston rides up and down in, that acts on the pin on the pump.

The seal around the piston is designed to hold pressure, it’s a V shape and if you can imagine as you put pressure on top of the V it expanse to make a better seal, and also not as efficient with a vacuum. Vacuum should not hurt the unit unless you put so much as to deform the bellows (they may expand to the point where they leak) but vacuum is not a good indication of the unit being serviceable. It should most defiantly hold pressure if all is good. There is a link with pictures of one apart; if I find it again I’ll post it.

So vacuum will expand the two bellows, thus pushing down on the pin limiting fuel for high elevations, and pressure will collapse the bellows letting the pin up allowing more fuel for the more air your getting, and the adjustment screw moves the two bellows up and down in the chamber.


found it http://articles.mbz.org/engine/diesel/alda/

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1993 300D 280K

Thanks I'll try that procedure.

My lift pump is not the same as the one I was reading about in a MB manual, so no stuck ball and spring...