ALDA Adjust Screw Busted - PeachParts Mercedes-Benz Forum

#1 12-19-2002, 03:12 PM

OK. I broke the adjustment screw on the ALDA.
I'm wondering if I can get the unit to function somewhat normally between now and replacement? The car is very slow before turbo spools up. Will plan to get another ALDA from Salvage yard. But that won't happen until after the holidays. Can anyone enlighten me?

adamb · #2 12-19-2002, 03:40 PM

Haaa, I did the exact same thing and the car ran but barely got out of its own way. My fix was to completely remove the ALDA and it now runs great!!!
I have no smoke, there is no oil coming out of the port and shaft from the top of the IP, and there is absolutely no reduction in fuel mileage. I am trying to get a good used one, though.
Fear not, it will be fine if you remove it until you get a replacement.

Thanks, Adam Bush

#3 12-19-2002, 03:44 PM

Hey, Adam. What kind of opening is left when ALDA is removed? And how did you cover it? I saw your previous posts and the pics. are great.

#4 12-19-2002, 05:53 PM

You know, I thought I was actually adjusting the ALDA by turning a small screwdriver down in the hole vacated by the broken adjustment screw. I don't think this actually accomplished anything more than making me feel like I was doing something. Story of my life.

crx · #5 12-19-2002, 11:32 PM

Where is the ALDA?

gsxr · #6 12-20-2002, 01:56 PM

Guys, photos of the ALDA taken apart, and the fitting on the I/P are all at this URL:

http://www.meimann.com/images/mercedes/OM603_intake/

If you broke the screw off the upper aneroid capsule, and the capsule is ruptured, you're screwed and need a new/used ALDA.

Regards,

#7 12-20-2002, 02:18 PM

Dave, thanks, I think. Is pucture of the capsule a given with the broken screw?

#8 12-20-2002, 02:21 PM

Oh yeah, pics. are excellent. I'll be examining the injector pipes this weekend.

gsxr · #9 12-20-2002, 02:33 PM

I'm not sure if the screw breaks off, if the capsule is always ruptured. Good possibility though. You can take it apart and squeeze the capsule. It should be "springy" from the air inside. Both should feel the same. If not, one is probably bad. When it ruptures, the bad ALDA will then give lots of fuel enrichment all the time when it shouldn't (off idle, low RPM, low boost) and the car runs terible - low power, smoking, etc. There is no quick fix, other than trying something to force the shaft down - like screwing in the top setscrew as far as possible. If the car runs fine with no ALDA, the "full load fuel" setting is way too low, and the I/P needs internal adjustments (something best left to a Bosch diesel injection shop.)

Oh, check out the other photos too, in the "parent directory".

#10 12-20-2002, 06:47 PM

Would sealing the hole vacated by the adjustment screw give the same results as removing the ALDA (as a temporary solution)? This would allow the turbo to remain useful.

gsxr · #11 12-21-2002, 12:36 AM

Depends if the capsule is busted. If so, sealing the hole won't do much, if anything. Worth a try though.

On second thought, removing the ALDA should NOT be a temp cure! The ALDA normally presses down on the I/P shaft, and boost allows it to rise. Removing it would be the equivalent of max enrichment. My previous post was wrong (I'll edit it after posting this). Adam has some other problem, and replacing his ALDA will either reduce power or have no effect. Betcha a six-pack.

Regards,

adamb · #12 12-21-2002, 02:25 AM

Hello
Other problems? I betcha a keg there is not, I would prefer Alaskan Amber too...
The reason is that when the ALDA is removed and the rod the ALDA influences is exposed enabling me to push it down and duplicate a non-boost condition. It is of course spring loaded so I couldn't set an intermediate setting and drive it.
If you think there are other problems, what do you think it could be, as the car seems absolutely perfect at this time?

On mine, and I believe on any ALDA adjusting screw that breaks off, will create a hole in the top of the diaphram rendering it completely broken and unrepairable. I tried to JB weld mine and had negative results.
ALDA replacement is a must for me, unfortunately, although it has been running great without it but I feel the itch to put one back on.

#13 12-21-2002, 08:25 AM

I have another ALDA. In order to install, do I have to take the Injection Pump off and take the whole assembly to Bosch shop? Or, can I just put the new ALDA in place?

adamb · #14 12-21-2002, 09:30 AM

I am not a certified Mercedes mehanic, but if it were me I would install the ALDA simply by removing the old one and installing the new one without touching anything else on the injection pump.
You will have to position the wrenches just right as there is a colar nut that remains on the IP and spins freely, then the ALDA can be turned for removal. The challenging part is to initially break it free with the minimal working room to swing the wrenches. Spray some rust-bust or penetrating lubricant there first.
when the ALDA is removed, start the car and see how it runs, even take it for a test drive and see how great it drives. Then replace the ALDA with the new one you got.
I know this a shade-tree method but it worked for me.

Have fun, please let us know how it turns out.
Adam

#15 12-21-2002, 10:02 AM

Adam, that's just the medicine. I really neede someone to give at least a glimmer of hope that I could get this done without taking the IP down and having the car down for an extended period.

Is the final position or orientation of the ALDA to the IP a critical factor?

And what size wrench do I need for the stationary nut that locks the IP down?

Thanks again.