Can you I.D. the parts in these photos? '85 300TD

Just trying to get an overall picture of what I’m dealing with when diagnosing the car for no power. I’ve read many of the posts and I need to see what parts we are talking about. So if some of you can identify these following parts, I’m sure us neophytes would appreciate it.

#1 On top of intake manifold at the rear


#2 (left) front of turbo, #3 (right) accordian shaped valve tube


#4 on left inner fender


#5 also on left inner fender further back


#6 behind brake booster to the right of booster


#7 also behind brake booster but to the left


#8 on top of injection pump

[Wasuchi]

I know #8 is the ALDA, #2 I think is a boost sensor, for the rest you'll have to wait for TXBill or someone else who knows a lot about these cars to identify that stuff.

[gsxr]

Oooo, a test!

1- Overboost switch on intake manifold (1.1 bar, +/- 0.1 bar, I think)

2- Air recirculation valve on turbo (emission control - this can be disconnected)

3- Corrugated pipe between exhaust manifold and EGR valve (EGR valve can be disconnected too)

4- Transducer(s) for air recirc valve and/or EGR valve (these can be disconnected or removed)

5- Vacuum amplifier for transmission vacuum circuit

6- Overboost switchover valve (signal from #1, above)

7- Transmission switchover valve (I think)

8- ALDA (anneroid compensator)


I may have #6 and #7 backwards, can't tell from the photos without tracing the vacuum (or pressure) tubes. The smog junk can be disabled or removed if you don't have emissions tests in your area, you may get a slight increase in MPG and part-throttle power. If you want an explanation of what all these do that would be a MUCH longer post!


HTH,

[adiaw83]

I've got a question about the alda in the picture. Mine looks like that to. Is that how it is supposed to look and if so, how to I access the switch witout causing problems?

[gsxr]

adiaw83,

Yes, that's how and ALDA looks. What switch do you want to "access" and why? The ALDA senses boost pressure and moves a control rod inside the injection pump to increase the fuel delivery as boost pressure rises.

[adiaw83]

I want to access the screw that people on here have been talking about. They say messing with that screw can make a huge difference in the performance of your car.

[gsxr]

Ah! Well, that will only make a difference IF your car is sluggish "off the line" right now. What you want to do is remove the little cap on top. Pry out the black seal to reveal the screw. Then use pliers to twist off the metal canister. When removed it will look like the photo below. Loosen the locknut and turn the screw CCW to richen the mixture. Try it in 0.5 or 1.0 turn increments. Most cars will need about 0.5-1.5 turns CCW. If you go too far the car may smoke or not run right due to an over-rich mixture.

CAUTION: This screw was not intended to be adjusted, hence the tamper-proof seal on top. There have been instances where people have adjusted it and it ruined the ALDA. You can't buy a new one from Mercedes - maybe from a Bosch shop, I don't know. Otherwise you would need to scrounge one from a junkyard.

More photos available here:
http://www.meimann.com/images/mercedes/OM603_intake/


Good luck,

[adiaw83]

hmmm I think I'm gonna give it a shot. When you take the tamper proof cap off, do you need to rebuild it once you're finished adjusting? also do you guys know anyone who has done this and ruined their ALDA becuase that would be a horrible mistake.

[gsxr]

If not "over richened" it should not kill fuel mileage. Like I said, if the car is running good now, leave it alone. The problem is knowing if your car is running as Mercedes intended. I had driven a dozen different 1987 300D's and TD's, and noticed a wide power variance between cars (at low, mid, and high RPM's). It wasn't until I bought my second one that I realized just how good the off-idle response is SUPPOSED to be. I have not touched the ALDA on that car and I don't intend to - it probably would not improve power at all. I am going to experiment on my first one though, since it is not as snappy and I want it to run as good as the second one does!

Something I forgot on my last post. I stated that the ADLA was not supposed to be adjusted - this is true. The enrichment is SUPPOSED to be adjusted internally on the pump, by a Bosch shop on a calibration bench. The ALDA controls the position of a rod internally, and the adjustment should be inside the pump on the internal linkage, not externally at the ALDA. But since it's major work to R&R the pump, plus $150-$250 to have a shop calibrate it, it's much easier to dink with the ALDA and hope it works!

Finally - the 240D and other normally-aspirated diesels only have an ALDA-type unit to adjust for altitude (if they even have an ALDA). Turbo diesels need it because of the turbo. It also compensates for altitude on the turbo motors, as explained in the OM617.95x engine manual (section 7, I think.) If the 240D mileage plummeted that low without a power loss (or smoke, etc), I'd suspect either the ALDA was damaged when adjusted (internal bladders can rupture) or something else happened at about the same time, i.e. fuel quality in your area changed, etc... 29 to 21 from an ALDA adjustment sounds pretty extreme!

[gsxr]

No, you just leave the tamper proof cap off, don't worry about "rebuilding" it. I don't know anyone personally, but I think there are one or two folks on the MBZ.org diesel list that had their ALDA break while adjusting it. Luckily the same ALDA was used on almost all Mercedes turbo motors through the 1980's (same on OM617 and OM60x), but I'm not sure about 1990-up... that would give you a wide selection for good used ones at a salvage yard!

[adiaw83]

thanks for the input. My car is horribly sluggish off the line but once the RPMS start to climb the turbo kicks in a bit. Also there is a lot of black smoke under heavy acceleration. at night time it is completely blinding to those driving behind me.

[gsxr]

If horribly sluggish off the line, the ALDA tweak MIGHT cure it. The cloud of black smoke behind you is not good though. A healthy Italian tuneup may cure that, if not, you have something else wrong with your engine. A properly running diesel will have a barely noticeable wisp of smoke in the rearview mirror, as seen on a sunny day. (DON'T test at night - even a good running diesel will appear to be smoky at night with headlights behind you. Wait for a sunny day!)


Let us know how it turns out if you try it!

[adiaw83]

I checked and during the day there is only a slightly visible trail of smoke. At nigth however it is completely blinding to people behind me