'87 300TD poor performance returns - PeachParts Mercedes-Benz Forum

msyoder · #1 12-09-2004, 01:51 AM

Hey Folks,

Haven't been very active for some time. In some ways that's a good thing (nothing realy bad has happend to the car in a while), but it's nice to read the familiar names in the posts and see the 603 engine community growing. Dave (gsxr), sorry about the hole in your engine.

Lately (over the last year) my performance has grown worse so I revisted the standard things: preasure lines and SOV to the ADLA are clean, changed the fuel and air filters. Finally I measured the boost and got only 5.5psi max at 4400rpms under full load acceleration. The manual indicates that this should be 11-12psi.

The boost preasure has been measured on my car at spec since the the trap oxidizer was replaced in 2000. Then my 0-50 times were 10sec. Now I'm lucky to get to that speed in 14-15 sec.

After a couple of enjoyable hours of reviewing the ADLA and power topics I understand that there is a feed back loop between the fuel enrichment and boost.

I'm getting the sense that my ADLA may be getting tired. And I should test a small adjustment and see what affect that has. I was just going to ask how one accomplishes the ADLA adjustment on the om603 with the manifold in the way when I ran across a link to Dave's excellent photos on the topic.

http://www.meimann.com/images/mercedes/OM603_injection/

I like the idea of the washer/shim to preserve the sealed adjustment screw. Does anyone think there is a downside to that over breaking the seal? What might the ratio of shim thickness to turns of the screw likely be?

Anyway, now I'm psyc'ed to get my baby back in the fast lane.

Thanks,

dieseldiehard · #2 12-09-2004, 11:47 AM

Hi, Mike
I question why the Alda would suddenly need adjustment after the car ran so well before. Boost can be lost if the flapper in the turbo waste gate gets hung up and fails to close.
This happened to my '87 and the solution was to free it up using some WD40 and elbow grease (WD40 to wash away the carbon stuff that was causing it to jam, there may be stronger stuff available but it wasn't necessary). My mechanic friend was planning to send the turbo to be rebuilt before this little salvation

I looked at a '87 300TD once, before I knew anything about the 603's and passed on it because it was a real slug. Knowing what I do now, I believe it had a plugged up trap oxidizer and possibly the wastegate was leaking. It was being offered for a quick sale and looked fine but the way it ran it felt like a 240D

OTOH, I have two wagons already and my wife would probably leave me if I bought another

I hope your able to restore the performance without messing with the ALDA and losing some fuel economy which is so geat in the 603 engine.
1971 220 (gas) 4-spd manual 106441
1979 300TD w/ ’85 turbo engine 295530
1983 300D 243280
1985 300TD 217300
1987 300D 258230

#3 12-09-2004, 12:41 PM

So you think messing with the ALDA will ruin economy?

Let me list my stats prior to adjusting the ALDA,

17(fixed HUGE fuel leak), 24, 31, 24, 22. I've been keeping track of every tankful since I purchased an '87 300D about 3 weeks ago (most were not full tanks). I've got a lead foot, and most of my driving is city or fast highway. The 31mpg tankful was all highway driving, the rest mostly city.

I just finished adjusting the ALDA in my car, and noticed a huge improvement. Before the car needed 1/2-3/4 throttle just to get moving from a stop. The turbo would kick in (and you would FEEL it) and all would be well above 20mph. Now I don't need more than just past idle to get going, and I don't feel the turbo much at all. The car feels much better at all speed ranges. I'm thinking this is how the car was supposed to run.

I hope the mileage does not get any worse, and I'm thinking since I don't have to floor the car to get going it's not going to. Even it it's adding more fuel off idle, I'm using much less throttle to get where I want to go. There is still no smoke from the exhaust when warmed up. I backed the screw out 1.5 turns CCW.

I've done a lot of tinkering over the past couple weeks, and replaced some leaking clamps and the air filter. Hopefully my mileage will stay around 30 if I keep the pedal off the floor

. I'm going to run some diesel purge and replace all the rest of the filters at the next oil change.

Lukejt

#4 12-09-2004, 06:17 PM

I adjusted my ALDA the other week and it hasn't affected fuel mileage significantly.
In my situation, it results in less time spent with the accelerator on the floor trying to get the car up to speed and dumping in fuel (concequently having to let off every time you hit boost).
Mileage was hovering around 25-27 and is about the same now...
I have the 617 but still should be similar results.

#5 12-09-2004, 06:53 PM

Quote:

Originally Posted by msyoder

Hey Folks,

The boost preasure has been measured on my car at spec since the the trap oxidizer was replaced in 2000. Then my 0-50 times were 10sec. Now I'm lucky to get to that speed in 14-15 sec.

Thanks,

Just thought I'd mention this, but it's measured 0-60

BB

msyoder · #6 12-10-2004, 12:47 AM

Hey, thanks all for the replies.

First, dieseldiehard, this degradation has been increasing over 4 years or more. I have complained (search for my id) about severe performace problems off the line at high altitude (Denver) since I owned this car. It would seem to make sense that if the ALDA is providing fuel a bit light at sea level it would be exagerated at altitude. It just keeps getting worse.

Nevertheless, I want to investigate the wastegate issue that you have identified. Can someone point me to a picture of what I should look for? I know that when I changed the head the soot buildup inside was shocking. It's perfectly reasonable that I have something cracked open that's robbing boost preasure. I'd love to find it and spend some time cleaning it out, but it's not clear to me where to find this problem.

As Lukejt and Brandon suggest going from a lean ALDA to a properly adjusted one should have no impact on fuel economy. How fast and far you go takes the same amount of energy no matter where your ALDA is set. The difference is how far you have to hold the throtle down to get enough fuel to the engine. Of course, sending unburned fuel through the engine is the same as a leak. Economy will suffer.

And finally, Busybenz, I live in an urban area, and find that 0-50 accelerations attract a little less attention and I can squeeze them in between lights on the west side highway of Manhattan.

Thanks,

msyoder · #7 12-11-2004, 09:50 AM

Well I've got the car parked out front and I'm going to take a look at the waste gate and/or give the ALDA a tweak.

psfred · #8 12-11-2004, 12:02 PM

A shim is better than messing with the screw for the simple reason that using the screw can damage the ALDA anaeroid or reduce the operating range. Actual bench adjustment is the shim, I think.

Peter

msyoder · #9 12-11-2004, 05:11 PM

Peter,

Thanks. When (if) I get to that I think I will go the shim route. But in the meantime I tested the ALDA for leaks and guess what? My problem seems to be a leaky ALDA. Gsxr says it should hold 15psi or leak down slowly.

All I had was my cheap generic parts store preasure gauge and my human lung Mityvac. First I tested my measuring equipment by blowing into the preasure hose connected to the gage covering the hole with my tongue and observing that the system held my mighty 2psi without any leak down.

Then I tested the ALDA by connecting my testing system to the ALDA where the preasure line connects and performed the same test. The ALDA leaks down from 2psi to 1psi in about 8 secs.

Based on GSXR's stats about I think these means my shaft seal is toast and I need to replace it. That would certainly explain my 5.5psi readings on boost preasure mentioned above.

Naturally the Manhattan Benz shop had no such part after going through 4 parts guys until I got the one that understood the part I was looking for.

The replacement ALDA is $145 retail here, but they didn't even have the whole thing. (This is actually the price for the primer pump assembly. Still have no idea what an ALDA unit sells for.)

I'll try a rebuild and see what happens.

Thanks all,

msyoder · #10 12-11-2004, 05:44 PM

Duh, I looked up the part number the dealer gave me and it's for the primer pump assembly.

Does anyone have the part number for the rebuild kit or the ALDA itself handy? Can't find the part by the name ALDA in the part store.

Thanks,

msyoder · #11 12-12-2004, 11:00 AM

From Dave's photo of this part below

http://www.meimann.com/images/mercedes/OM603_injection/ALDA_top.jpg

I found this number: 1-427-133-150

But can't find that part.

ewstan · #12 12-13-2004, 11:30 AM

Quote:

Originally Posted by msyoder

Hey Folks,

Lately (over the last year) my performance has grown worse so I revisted the standard things: preasure lines and SOV to the ADLA are clean, changed the fuel and air filters. Finally I measured the boost and got only 5.5psi max at 4400rpms under full load acceleration. The manual indicates that this should be 11-12psi.

Thanks,

After you check the obvious, I'd suggest you test the exhaust backpressure. I went through the whole list of potential causes before discovering that the CAT was plugged.

Wray

Rick Miley · #13 12-13-2004, 12:32 PM

Did you call Phil at Fastlane to ask about the parts?

SW · #14 12-13-2004, 01:35 PM

Get a used one from a junker. I would do a leak test prior to purchase. The ALDA's from some of the w123's work as well.

msyoder · #15 12-13-2004, 03:10 PM

SW -- Looks like I may have to go that route. Phil at Fastlane and Tom Hanson at Caliber both confirmed that this part is not sold separtately from the injection pump.

Dave M., did you ever get around to making those ALDA refurbish kits that you mentioned once upon a time in thread far far away?

If anyone has one that doesn't leak. I'd be interested in talking. Now that I believe I know what the problem is I'm eager to try the fix.

Thanks,