How do I clean the ALDA vacuum lines?
 

What’s the proper procedure for cleaning the vacuum lines and associated connection points around the ALDA? I’ve heard a lot of talk about these lines being clogged and causing poor acceleration and fuel economy (which is what I’m experiencing).

1992 300D 2.5 with 270K miles

I used brake parts cleaner on mine. It blew out a bunch of black gunk. My banjo bolt was filled with gunk as well and I used the same process to clean it. Sure runs better when that stuff is clean!

are there any pictorials on this?

-OB

That banjo bolt looks like a real pain in the ass to access on my vehicle. Do you have to take off the intake housing to access it?

Mine is real easy to get to. (W123) I beleive it is a 12 mm wrench, just loosen it up. It is a pretty long thread. There were two washers on mine, one in front of and one behind the metal coupling the banjo bolt runs through. Just be careful and catch both washers. Really an easy job. Took me about 15 minutes to clean the ALDA and all tubing and bolts.

The crud originates at the manifold end and progresses toward the ALDA, so you want to disconnect and clean in the opposite direction. Brake or carb cleaner worked best for me. The banjo bolt may be a PITA to get to, but it would probably be the dirtiest, and definitely should be cleaned (if dirt in the lines is actually your problem).

My lines are clear plastic, making them easy to check.

Wes

Obnoxio-
Here's a good link to the Diesel Giant pictorial. When I did mine last week, I found the line to be clogged as well as the banjo bolt.
After a half hour of ceaning out the nasty stuff (wear gloves if you got 'em!), I feel like I'm driving a different car. Maybe a 15-20 hp boost. Pretty cool, and free!

http://dieselgiant.com/mercedesaldaboostsystemservi.htm

good luck-
Kevin

Contrary to popular belief the 300D 2.5T does not have a banjo bolt. However, the fitting on the intake manifold is just as bad for clogging up. Make sure you pull it first before taking out all the pressure lines for the ALDA. When I first did mine, it was caked up with oily EGR crud, and the lines were relatively clear.

Can I spray the inside of the lines and the ALDA interior with intake cleaner?

By the way, I really like the BG44K Intake Cleaner. We use it a great deal on Land Rover intake pleniums for carbon build up.

Here is the pictorial for the OM602. If you want to clean the rubber lines, disconnect them from the various sensors and ALDA first. Last thing you want to do is blow a bunch of crap where it doesn't belong.

Forget cleaning the ALDA pressure lines (they are pressurized, not under vacuum). Just replace them. At a cost of a couple bucks per meter, it's just not worth it. They are often fossilized and brittle after 10-20 years, as are the rubber fittings. Here's a post with more info & part numbers:

http://www.***************/forum/showpost.php?p=3071&postcount=4

Yes, I replaced what looked bad with what I have in my garage. I had to order a few connectors and some additional vacuum line. The ALDA was clogged at the unit and intake. Cleaning did make a difference but didn't correct 100% of my problem.

Here is the link to the pictorial on the ALDA cleaning.

http://dieselgiant.com/mercedesaldaboostsystemservi.htm

Ok now what...
 

I've cleaned the banjos, cleaned the tubes, now how do you clean the ALDA itself and the vacuum switch? Can these by flushed out with brake type cleaner or blown out with an air compresser or hooked up to a shop vac, or a combination of all three? Thanks.

First, it's not a vacuum switch, it's a valve that either lets the pressure (not vacuum) flow, or not flow. :) Anyway, the ALDA itself does not require cleaning. However, the switchover valve can get plugged, and it can be very hard to clean out. You can try carb cleaner and compressed air. In the normal position, you should be able to blow through it without major resistance. When energized, it blocks the airflow (cutting the pressure signal to the ALDA, which cuts the fuel enrichment). If you can't clean the valve well enough, replace it. To see if it's cleaned well enough, temporarily bypass the valve... there should be the same power output either way. If you lose power when the valve in the circuit, either it's not clean enough and needs replacement, or the pressure lines are connected to the wrong ports. (Or, there's an electrical problem, but that's less likely.)

Another option (which I don't recommend, but I have done this, and other people have too) is to simply bypass the valve entirely. It's an overboost safety, in case the turbo wastegate sticks shut, but in reality the IP's full-load fuel limit will prevent engine damage. I think on later models (late 2.5T's?), MB deleted this valve.

Here's photos of what the ALDA looks like inside - those round discs (aneroid capsules) are sealed, and compress/expand with pressure from the turbocharger, allowing the signal rod on the injection pump to move up or down as boost changes:
http://www.w124performance.com/images/OM603_injection/


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