M73 DK Motor disassembly and cleaning, Questions

[samsonevickis]

Has anyone done this?

I have cleaned and corrected numerous M70 DK motors, but am unsure of how to clean the M73 ones. I don't want to break anything. Cant find any info specific for them.

Thanks

[shogun]

As far as I have read on the German forum, the Siemens DKs for the M73 are not servicable, much more complicated design than the Bosch DK for the M70 engine

[samsonevickis]

Thanks Erich,

I was told by another member here that it could be done, but have found zero evidence that it's possible from any other single person.

[samsonevickis]

What options are there for the M73 DK motors?

I mean I can just get low mileage used ones, but surely they mess up for the same reasons the M70 ones do, just need a cleaning.

[CPHES]

What are your symptoms?

[samsonevickis]

Not really a symptom.

The car had the "ENGINEFAILSAFE" message on every start up for about 2yrs, after it sat for the previous 5, never seemed to cause any issues while driving, then back in Sept it just didn't come back on anymore. No other codes or issues.

But there seemed to be a dead spot on acceleration, almost felt like it was missing around 2200-2400, but accelerate through it and its just fine. Then about a month ago, I'm on the interstate and it almost felt like limp home mode was about to occur, I wouldn't push it any harder on acceleration and was able to nurse it home with minimal effort, I just figured it was finally time to take it off line and do the cleaning.

So I did some research and with no codes, but the Failsafe warning it was akin to the older E32 EML light, which meant DK motors need cleaning, when I had that issue on my E32 I took the motors off, they were in fact filthy, I cleaned them and reset them and the car drove great until I parted the car nearly 2yrs later. Bad trans.

I was just looking to open them up, clean them, reassemble. If you know of any links or documentation, that would be helpful

[shogun]

On the German E38 Forum we discussed that 11 years ago, I now pushed that up again and asked if there are any new and detailed DIY instructions for the Siemens DK like the ones for the Bosch M70 DK on my website. But the Siemens looks completely different. At least some have partially disassembled and cleaned the Siemens, pics below. Some comments, translate that, if there are any new comments coming, I will post it here:
Ich hab bei meinem E38 750 die Klappen gereinigt. Der Motor ist unproblematisch und auch so überdimensioniert, das er vermutlich nie ausfallen wird. Die Klappe und den Ansaugtrakt kann man mit Bremsenreiniger oder ähnlichem Reinigungsmittel sauber bekommen. Das Problem ist das Potentiometer. Dieses ist verhaeltnismässig leicht auszubauen. Hinten den Plastikdeckel mit dem Stecker abschrauben (4 Schrauben). Dann kann man das Potentiometer mit 2 Schrauben loesen und herausnehmen. Die 6 Draehte aus den Fuehrungen des Plastikdeckels ziehen und den Deckel entfernen. Vorsicht! : die Feder geht gerne fliegen...
Die Bahnen des Potentiometers mit Leiterplattenreiniger oder aehnlichem reinigen und die "Bürsten" vorsichtig mit einem Glasfaserpinsel saeubern. Danach das Poti wieder zusammensetzen (Feder nicht vergessen) und mit etwas Oszillin oder Tuner600 einspruehen. Nun das Poti wieder in das Gehaeuse legen und auf korrekten Sitz achten! Es muss vollstaendig am Gehaeuseboden anliegen sonst bricht es beim Anschrauben. Die Schrauben des Potentiometers nur mässig anziehen, Bruchgefahr! Klappe wieder schliessen und einbauen. Anschliessend empfehle ich noch einen "Reset" durchzuführen. (Batterie für 1 Stunde abklemmen und dabei Zündung auf "an". Fehler wie hochlaufen der Drehzahl beim Einschalten des Klimakompressors oder wüstes Schalten des Getriebes im Schiebebetrieb sind dann nicht mehr.
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habe gerade eine DK zum testen von ebay gekauft, habe zerlegt und sie war in gutem Zustand. Kein Abrieb oder Dreck. (download the pics before they disappear)
Entfernter Kabelstecker und zerlegter Poti http://img.photobucket.com/albums/v4...h_DSCF0151.jpg
Poti-Bürsten http://img.photobucket.com/albums/v4...h_DSCF0152.jpg
Motor-"Welle" http://img.photobucket.com/albums/v4...h_DSCF0153.jpg
Leiterbahnen http://img.photobucket.com/albums/v4...h_DSCF0154.jpg
Wieder eingebauter Poti http://img.photobucket.com/albums/v4...h_DSCF0155.jpg
Ebay-DK in der Mitte, 2 alte DK außen http://img.photobucket.com/albums/v4...h_DSCF0156.jpg
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Ich hatte die DK auch komplett zerlegt, aber dann waren sie defekt / kaputt. Ob das Poti reinigen so viel bringt? Ich wuerde es nur machen, wenn Ersatz bereit liegt, weil die Gefahr des Zerstoerens ist sehr hoch. Man sollte vielleicht noch sagen, dass man die Drosselklappen auf keinen Fall mit Bremsenreiniger fluten sollte! Nur mit einem damit getraenkten Lappen ausputzen, ich habe mit dem Fluten mir eine Drosselklappe zerstoert
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schlechte Nachrichten, nach dem Putzen und einbauen startet mein M73 Motor nicht mehr. Der Starter dreht, aber der Motor startet nicht. Wenn ich die Zündung einschalte, klappen die DK mehrmals ein paar mm auf und zu, reagieren dann aber nicht mehr auf meinen Gasfuß. Woran kann es liegen? Ich werde sie nochmal öffnen und mit den Bildern von vorher vergleichen. Habe die Dk wieder geoeffnet und noch einmal zusammen gebaut, und der Motor startet wieder. Hinweis: Beim Zusammenbau darauf achten, dass die Feder (spring) vor dem zuschrauben wieder zurück gedrueckt wird. Das erspart viel stress beim Wiedereinbau.
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ich habe auch beide Drosselklappen ausgebaut, Klappen mit Bremsenreiniger vorsichtig gereinigt und Potentiometer mit Isopropanol gereinigt, danach Potentiometer und Klappen leicht mit Caramba geschmiert, was ja sowohl Kontaktspray als auch Universal Schmiermittel ist. Die Klappen waren sehr dreckig, die Potis hatten leichte "Staubberge" an den Schleifbahnenden angeschoben. Die Stellantriebe (Motore) hab ich nicht demontiert.

[samsonevickis]

Ah excellent.

I didnt remove the pointimeter screws as I was unsure of what was going to happen, now I know to be prepared.

None of the pics are loading currently, but the transmission shudder is exactly what I am looking to eliminate.

Good to know I'm somewhat on track with my diagnosis.

- - - Updated - - -

Erich, also, I was just telling a story about you the other day, I ordered one of your SRS reset tools back in 2010, it got from you to me in 3 days! Some weird express shipping from Japan.

Then the countless bits of advice you have given over the years and here you are today, BOOM.

Really appreciate it.

[shogun]

Pics will work, but be patient, takes about 30 seconds, very slow. Best is you download them then.

[CPHES]

This is the google translate from the German above - in sequence

I cleaned the flaps at my E38 750. The engine is unproblematic and also so oversized that it will probably never
fail. The flap and the intake tract can be obtained cleanly with brake cleaner or similar detergent. The problem
is the potentiometer. This is easy to expand. Unscrew the plastic lid with the plug (4 screws).
Then you can loosen the potentiometer with 2 screws and take it out. Pull the 6 draed-in from the guides of the
plastic lid and remove the lid. caution! : The spring likes to fly ...
Clean the lanes of the potentiometer with PCB cleaner or similar and gently sour the "brushes " with a fibreglass
brush. Then put the poti back together (don't forget spring) and scour in with some oscilline or
Now put the poti back in the gehaeuse and pay attention to the correct seat! It must be fully attached to the
haeus-floor otherwise it breaks when screwing. The screws of the potentiometer tighten only moderately,
risk of breakage! Close and install the flap again. Then I recommend performing a
"Reset ." (Clampe battery for 1 hour while igniting "an ."
Errors such as running up the speed when the climate compressor is switched on or the gearbox's aging
in sliding operation are no longer.
I had also completely disassembled the DK, but then they were defective/broken. Whether cleaning the poti brings
so much? I would only do it if replacement is ready because the risk of crushing is very high. It should perhaps
be said that you should not flood the throttle flaps with brake cleaner! Just brushing out with a rag dripped
with it, I crushed a throttle with the floodwaters
Bad news, after cleaning and fitting my M73 engine no longer starts. The starter spins, but the engine doesn't
start. When I turn on the ignition, the DK fold up and down several times a few mm, but then no longer react to my
gas foot. What can be the reason for it? I will open them again and compare them with the pictures from before.
Have opened the Dk again and built it again, and the engine starts again. Note: When assembling, make sure that
the spring is pushed back before screwing. This saves a lot of stress during reinstallation.
I also removed both throttle flaps, carefully cleaned flaps with brake cleaner and cleaned potentiometers with
isopropanol, then smeared potentiometers and flaps lightly with Caramba, which is both contact spray and
universal lubricant. The flaps were very dirty, the Potis had slightly "dust mountains " pushed on to the
grinding ends. I didn't dismantle the actuators (Motore).