Throttle-linkage question 300D 1985 california - PeachParts Mercedes-Benz Forum

DocMichael · #1 05-28-2006, 12:05 AM

Guys,

does someone has experience with the throttle-linkage adjustment on a 300D (Turbo), model year 1985, California version? The online shop-manuals don't cover that model, it has a different layout on the valve cover.
I have made two pictures to clarify my question. One is IDLE the other is WOT. I wonder, if that small bushing (red arrow) should be of larger diameter, e.g. the diameter of the metal rail? Mine is apparently worn out, it looks so small. Is there a part-number or source where to obtain it from? Can I make a quick fix with some sort of washers/bushings from home depot? What material - Metal? Nylon?

And also: where should it be at IDLE, on the top left "corner" in that metal rail?

Symptoms:
- indirect, fluffy feeling accelerator pedal
- late upshift unless you get your foot one inch off the pedal
- no downshift uphill unless using kickdown or manual selector
- idles ok

Any advice will be appreciated!

Michael

Jeremy5848 · #2 05-28-2006, 12:26 AM

The roller bushing to which your arrow points is the same on mine. When the engine is stopped, it is in the upper right (see picture). It goes to the upper left when you push the manual stop lever. I am too new to comment on your symptoms but the linkage in your picture would not seem to be worn or damaged.

jt20 · #3 01-07-2009, 08:52 AM

I am currently returning ~18 mpg... and I drive rather gently.

Besides a twitchy front end and a somewhat dragging front caliper, I cannot justify this terrible mileage.

-Engine has excellent compression
-trans is responsive but shifting improperly
-valves, timing and engine mechanicals are set.

Since the recent timing I did, I have not been able to set the linkages very well. (FSM sucks for '85 cali engines) Could they cause poor mileage to this degree? Could the trans Bowden cable cause this as well?

What are some effective methodologies for adjusting the Cali throttle linkages?

Jeremy5848 · #4 01-07-2009, 12:26 PM

A few things to think about –

18 mpg is a bit low. Does your car still have its trap catalyst? That reduces mileage by several and a clogged cat is even worse. After 2+ years, my '85 (with trap cat) has averaged 21 mpg in mostly around-town driving. I have not driven enough following removal of the trap cat to have a good hack on the post-trap mileage but it should be better.

I have never had to adjust the throttle linkage on my '85 but I don't see that it would necessarily affect mileage. All you need to do is to make sure that you can get the IP all the way to the stop when the footfeed reaches the kickdown switch. Have you tried adjusting or removing ALDA, made sure the boost line is unclogged, etc.?

Shifting is a function of vacuum (how hard) and Bowden cable (timing). Make sure the VCV is functioning correctly and that the blue flying saucer is getting the correct boost and vacuum signals. You can use the 1987 OM603 manual since it has a nearly-identical setup to the 1985 OM617 (I own one of each).

Many folks here have related poor mileage to injectors. I have never had to work with them and can't help there.

What fuel are you using? Pure biodiesel (B100) will drop a mile or two from your economy, compared to D2.

Jeremy

DSlater · #5 01-07-2009, 01:00 PM

Is the lever on the side of the IP hitting the throttle stop screw at WOT? Can't tell from the pic.

jt20 · #6 01-07-2009, 01:11 PM

Quote:

Originally Posted by Jeremy5848

A few things to think about –

18 mpg is a bit low. Does your car still have its trap catalyst? That reduces mileage by several and a clogged cat is even worse. After 2+ years, my '85 (with trap cat) has averaged 21 mpg in mostly around-town driving. I have not driven enough following removal of the trap cat to have a good hack on the post-trap mileage but it should be better.

Still have the catalyst, and I do not believe it is clogged, it looked rather clean when inspected. Also, the difference in horsepower for models w/ and w/o is less than 5 hp at at the top of its range. At low rpms and load, this cannot translate to much.

More importantly there was an exhaust leak there which has been minimized, but still exists. Perhaps this is also a source?

Quote:

Many folks here have related poor mileage to injectors. I have never had to work with them and can't help there.

What fuel are you using? Pure biodiesel (B100) will drop a mile or two from your economy, compared to D2.

Jeremy

I run D2 and have rebuilt the injectors.

jt20 · #7 01-07-2009, 01:17 PM

also, when should the electronic switch on the VC engage? Is it a part of the kickdown function?

Jeremy5848 · #8 01-07-2009, 02:08 PM

The kickdown switch is on the floor, under the throttle pedal. The switch on the valve cover is for the Klima relay, it turns off the a/c compressor at full throttle, to reduce the load on the engine while you're running from whoever you're running from.

jt20 · #9 01-07-2009, 02:20 PM

thanks again.

what if the vacuum control is not reaching its stop @ full throttle?

Chad300tdt · #10 01-07-2009, 02:25 PM

Wow Jeremy!!! You've done a lot of beautification since post #2.