ALDA removal........OM603 - Page 23 - PeachParts Mercedes-Benz Forum

Jeremy5848 · #**331** 07-31-2007, 08:56 PM

OK, thank you. This ALDA is virgin, it still has the original cap.

By the way, what is the thing with all the hoses attached to it, on the side of the IP below ALDA (circled in red in the photo)? I noticed that the rubber fitting that the arrowed line goes into is split -- I'll temporarily clamp it but it will need to be replaced as soon as I can find that part.

Jeremy

Brian Carlton · #**332** 07-31-2007, 08:56 PM

Quote:

Originally Posted by Jeremy5848

After a short but intense struggle, I got the ALDA off of my '87. Exercising it on the bench with my Mitivac, I noticed that the ALDA's inner works moves up (relative to its installed position on the IP) as Mitivac pressure (mimicking turbo boost) is applied to the diaphragm via the hose barb. That would in turn allow the plunger on the IP to move up, presumably allowing the IP to squirt more fuel into the engine. Do I understand correctly?

However, I also noticed that often during the exercise the plunger in the ALDA snapped back to its original position with a soft but noticeable "click." Is this supposed to happen? It didn't seem to matter how much or little pressure was applied to the ALDA or how long it was applied. It almost always happened and it took a second or a few seconds after I started pumping the Mitivac.

You've got it down perfect.

The reason that it snaps back to the original position is that it leaks. Just about all of them leak. But, the engine has an unlimited supply of air for boost, so the leak past the shaft seals is nothing to be concerned about. Naturally, unless you keep pumping the Mityvac, the ALDA is going to return to it's preferred position..........the up position..........without any fuel enrichment.

Brian Carlton · #**333** 07-31-2007, 08:57 PM

Quote:

Originally Posted by Jeremy5848

OK, thank you. This ALDA is virgin, it still has the original cap.

By the way, what is the thing with all the hoses attached to it, on the side of the IP below ALDA (circled in red in the photo)? I noticed that the rubber fitting that the arrowed line goes into is split -- I'll temporarily clamp it but it will need to be replaced as soon as I can find that part.

Jeremy

That's the vacuum control valve for the transmission on a 603. It feeds the amplifier (blue flying saucer) on the driver's fenderwell.

Jeremy5848 · #**334** 07-31-2007, 09:16 PM

...and possibly related (the split in the connector, I mean) to why the tranny shifts very hard? I need to go through all of the rubber jumpers in and around that blue vacuum amplifier and replace many or all of them, I bet.

I put a layer of shrink tubing over the split rubber, maybe it will make a slight improvement. The rubber elbow looks like it fits into the vacuum control valve. I hope FastLane has or can get that part and that I don't have to take the thing apart to get the new one in.

Brian Carlton · #**335** 07-31-2007, 09:20 PM

Quote:

Originally Posted by Jeremy5848

...and possibly related (the split in the connector, I mean) to why the tranny shifts very hard? I need to go through all of the rubber jumpers in and around that blue vacuum amplifier and replace many or all of them, I bet.

I put a layer of shrink tubing over the split rubber, maybe it will make a slight improvement. The rubber elbow looks like it fits into the vacuum control valve. I hope FastLane has or can get that part and that I don't have to take the thing apart to get the new one in.

You bet right.

Shrink tubing? WTF. Go out and get the proper hoses and replace the old crap under there. You'll never get smooth shifts until you do.

The '86 required all new rubber to function properly. It slammed into gears when I first purchased it.

Jeremy5848 · #**336** 07-31-2007, 09:43 PM

You can see how long I've been in electronics -- I fix everything with heat-shrinkable tubing! But yes, Dad, I'll replace all the rubber parts.

Just back from the test drive, no performance improvement noticed, still slow acceleration, tranny still shifts hard. Gotta be something in the IP or the various pressure and vacuum signals that it receives from wherever they come from.

Brian Carlton · #**337** 07-31-2007, 09:47 PM

Quote:

Originally Posted by Jeremy5848

You can see how long I've been in electronics -- I fix everything with heat-shrinkable tubing! But yes, Dad, I'll replace all the rubber parts.

Just back from the test drive, no performance improvement noticed, still slow acceleration, tranny still shifts hard. Gotta be something in the IP or the various pressure and vacuum signals that it receives from wherever they come from.

Dad here.

Did you put a boost gauge on it yet?

Jeremy5848 · #**338** 07-31-2007, 09:59 PM

That's on my list, gotta figure out where to put it -- the W124's cockpit is a little more crowded than the 123's. I did check and clean the fittings and lines from the manifold to the "safety valve" and thence to the ALDA, gunked up a little but not clogged. I need to remove and clean out the manifold itself; if it's anything like the crossover tube, it's bad. At least with the EGR temporarily removed for testing purposes only (I swear, officer), it won't get worse.

The turbo is new, replaced by the dealer as part of the trap ox "campaign" (they said it had been "damaged"), but even so, the only way to know for sure is to have a gauge. I'll move it to the top of the list. Thanks for the reminder.

Brian Carlton · #**339** 07-31-2007, 10:04 PM

Quote:

Originally Posted by Jeremy5848

That's on my list, gotta figure out where to put it -- the W124's cockpit is a little more crowded than the 123's. I did check and clean the fittings and lines from the manifold to the "safety valve" and thence to the ALDA, gunked up a little but not clogged. I need to remove and clean out the manifold itself; if it's anything like the crossover tube, it's bad. At least with the EGR temporarily removed for testing purposes only (I swear, officer), it won't get worse.

The turbo is new, replaced by the dealer as part of the trap ox "campaign" (they said it had been "damaged"), but even so, the only way to know for sure is to have a gauge. I'll move it to the top of the list. Thanks for the reminder.

No, you don't need a permanent place. You just hook it up in parallel to the ALDA and run the gauge into the cockpit via the driver's window. 10 minutes to set it up and you can get some valuable info.

I don't have permanent boost gauges in any of these. But, I know that all of them are doing.........

Jeremy5848 · #**340** 07-31-2007, 10:46 PM

I suppose I could even use my Mityvac, since it is the pressure/vacuum version. That would save buying a gauge and I could do it now.

[edit]
OK, there's boost. I ran a line from the Y-connector that no longer goes to ALDA into the passenger compartment via the window -- thanks, Brian -- to my Mityvac. Took the car for a ride. Maxed out at about 11 Mityvac PSI. Still doesn't perform like the two 124 300TDs I drove last week.
[end edit]

By the way, could this spare port on the manifold (see picture) be used for a more permanent installation?

Brian Carlton · #**341** 07-31-2007, 11:21 PM

Quote:

Originally Posted by Jeremy5848

I suppose I could even use my Mityvac, since it is the pressure/vacuum version. That would save buying a gauge and I could do it now.

[edit]
OK, there's boost. I ran a line from the Y-connector that no longer goes to ALDA into the passenger compartment via the window -- thanks, Brian -- to my Mityvac. Took the car for a ride. Maxed out at about 11 Mityvac PSI. Still doesn't perform like the two 124 300TDs I drove last week.
[end edit]

By the way, could this spare port on the manifold (see picture) be used for a more permanent installation?

Well, that's a good start. 11 psi is right on spec.

Do a 0-60 time with a good stopwatch. Take someone with you to time it.

Report back with results.

gsxr · #**342** 07-31-2007, 11:28 PM

1) The only way to tell if the ALDA is leaking is to use a MityVac to pressureize it, while the ALDA is installed on the IP. If you can't pump it to 10-15psi, the shaft seal is leaking. You can replace the seal (about $5 from Jim Friesen) to effectively "rebuild" the ALDA. When the shaft seal leaks, you will lose part-throttle power if the leak is bad enough. But it won't affect full throttle power, since as Brian noted, the turbo can supply enough boost pressure to keep the ALDA in the "max fuel" position despite the leak.

2) The rubber fitting coming out the side of the VCV is only a vent line. A leak there WILL NOT affect shifting, at worst, it will allow some dust & dirt to enter the vacuum system. The 90° fitting is not available separately, but can be replaced with a straight (180°) fitting from an M103 fuel pressure regulator, which happens to be similar. Part number is 000-078-02-81.

3) If the Tecalan (plastic) tubing in the engine compartment is old and brittle, replace EVERYTHING with new, and replace every rubber fitting that isn't in very good shape. Like Brian said, it will never work right if it's patched together. And besides, it's cheap to fix it properly - about $25 in tubing, hose, and fittings. Part numbers for all that stuff is in this thread.

4) Your power problem is puzzling, given that boost is 11psi (normal) and the ALDA was removed. Time to start with the basics... air filter, fuel filter, fuel tank strainer, dragging brakes, cam timing, pump timing, etc. I can't imaging an almost-new catalyst would be plugged, but if everything else checks out, I'd look at that next. Oh, make sure the EGR valve isn't stuck open, or the ARV (best to disable both of them regardless.)

5) Yes, if you want to install a permanent boost gauge, the spare port on the manifold will work fine. I wouldn't bother unless you're planning to increase power beyond the stock 148hp, though.

gsxr · #**343** 07-31-2007, 11:33 PM

Quote:

Originally Posted by Brian Carlton

Do a 0-60 time with a good stopwatch. Take someone with you to time it. Report back with results.

Agreed. If it's 11 seconds or better, you're not going to get much faster without mods. If you're in the 14-second range or slower, something ain't right. Check the speedo accuracy with a handlheld GPS, if you have access to one. Oh, and if you're much above sea level, you'll lose power... above 3000' or so and it's quite noticeable off idle.

Jeremy5848 · #**344** 07-31-2007, 11:40 PM

OK, I'll work through all of the vacuum and pressure lines. The EGR has been removed in favor of one of Brian's kits and the ARV line has been plugged. I plan to remove all of the plumbing from under the air cleaner for those two. The air filter is new. The fuel filters have relatively few miles on them and performance has not changed since they were new.

Since removing the ALDA had no effect, the problem obviously isn't there, in which case I might as well put it back on. I'll first remove the seal and try a 1.5 turn CCW adjustment.

Thanks for the suggestions.

gsxr · #**345** 08-01-2007, 12:05 AM

Quote:

Originally Posted by Jeremy5848

Since removing the ALDA had no effect, the problem obviously isn't there, in which case I might as well put it back on. I'll first remove the seal and try a 1.5 turn CCW adjustment.

Well... don't be too quick to dismiss the IP. WIth the ALDA removed, press down on the plunger. It should easily move up & down, and be under spring pressure. I've heard of the rod getting corroded so it was "stuck" in the down position, so it would never increase fueling. This is a long shot, but worth a try. It's also possible the pump is just way low on fuel delivery and needs a bench calibration (again, not too likely.)