300SDL Accelerator - PeachParts Mercedes-Benz Forum

P.E.Haiges · #1 05-07-2003, 11:48 AM

This is to other owners of 300SDL 6 cylinder MB.

Do you have to push the accelerator to the floor to get much power or acceleration from the engine? The 126 300SDL accelerator has an altogether "feel" than my 116 300SDs. The 300SD accelerators are responsive to a small displacement but the same displacement of the 300SDL makes for extremly slow acceleration.

As far as the Cruise control working, it appears to push the accelerator linkage "all the way down" when acceleration is called for but keeps a very constant road speed. Due to the the different characteristics of the 300SD and 300 SDL torque converters, the 300SDL engine speed varies widely (up to 800 RPM), but the car speed remains constant.

What I am actually asking is do other 300SDL accelerators have the same characteristics of needing to be pushed way down like mine?

P E H

sixto · #2 05-07-2003, 03:59 PM

I don't know if I'd describe the difference between my SD and SDL to be based on the amount of pedal travel. With a moderate push on the pedal, the SD will squat its rear and lurch forward. The SDL isn't as abrupt even if I floor it off the line.

I find that the SDL engine is more responsive to changes in throttle but it takes the transmission longer to catch up.

Could be that over 200K miles on each set of throttle linkages has takes a different toll.

Sixto
91 300SE
87 300SDL
83 300SD

#3 05-07-2003, 05:54 PM

Go wad up some paper towels and replace the throttle linkage bushings with that. God forbid you spend any money on it. I have zero pedal travel, I adjusted as such that a mouse on the acclerator pedal will produce engine response.

P.E.Haiges · #4 05-07-2003, 06:12 PM

TurboD,

I'll check to see if any of the bushings are loose or worn.

What did you adjust to get the better accelerator response? Mine seems to push too hard, is there an adjustment for that, different return spring?

I don't mind spending money on something that's broken or worn excessively, I just don't believe in replacing parts just because they are old or have so many miles on them. If it ain't broken, don't fix it is my motto.

P E H

P E H

psfred · #5 05-08-2003, 12:56 AM

PEH:

My 300D (same engine) is sluggish off the line, takes off when the turbo comes up. Hard to regulate speed, it tends to "climb" rather badly!

I'll ask my brother about the difference between his 300D and 300SDL.

Peter

P.E.Haiges · #6 05-08-2003, 06:23 PM

P S,

My 300SDL takes off OK, its just that the accelerator has an altogether feel than my 300SD.

If I just touch the 300SD pedal, there is an increase in engine speed and the car accelerates wheras it seems I have to push the 300SDL pedal all the way to the floor to get the same response.

I was just wondering if other 300SDLs have the same accelerator pedal characteristic or if there is something different about mine.

P E H

BJ300SDL · #7 05-08-2003, 08:39 PM

PEH My 87' sdl seems to be like any other diesel when it comes to throttle inputs. I usually operate the car between 1/4-1/3 throttle. Sometimes 1/2. The car will flat out haul under full throttle. Check the solenoid between the int. manifold and the alda, sometimes it gets plugged with soot and the power is low and slow. Hope this helps! Barry

P.E.Haiges · #8 05-09-2003, 10:16 AM

BK300SDL,

Its not a problem with low power in the 300SDL, its just that I have to stomp on the accelerator to get the power. Also the accelerator is much harder to push than my 300SDs.

I would like some more response with the 300SDL accelerator about 1/2 way down like my 300SDs and a lighter force needed to depress the 300SDL accelerator.

I wish I could find another 300SDL to compare it too. Maybe I will have to go to one of the meets to find another one. There are not many 300SDLs around here.

P E H

TX76513 · #9 05-09-2003, 10:33 AM

I had the same thoughts about my SDL vs the 5 cyl D. The low end was doggy. I did some research on this site look at the link below from 1/11/02 made all the difference in the world for my SDL.
http://www.peachparts.com/shopforum/showthread.php?threadid=29482[/U]

P.E.Haiges · #10 05-09-2003, 10:49 AM

TX,

THe BB trick was already done, but I haven't taken off the crossover pipe or intake manifold yet to check for blockages. I haven't been able to compare it to another 300SDL but it seems to have a lot of power (for A Diesel). Its just that the accelerator response is not like my 300SDs which I prefer.

P E H

P.E.Haiges · #11 05-11-2003, 02:23 PM

Turbodiesel,

You haven't told me how you adjusted your 300SDL accelerator to change its response so a mouse can operate it.

I'd like to adjust my accelerator for a better response at light force and less travel of the pedal. I don't want a mouse response but maybe a cat response would be OK

P E H

Lance Allison · #12 05-11-2003, 10:10 PM

Good luck with this one. My 300SDL is the same way...you really need to start off with a heavy foot to get momentum going. I've driven a few 124 and 126 cars with the 603 and they seem to have similar pedal response.

Often times, I find myself flooring the car from a stop and feel "guilty" that maybe I'm pushing the car too hard...but I don't suppose that is really an issue.

PaulH · #13 05-11-2003, 11:35 PM

When I bought my '87 300SDL new, the pedal was hard to push. The dealer said (in '87) that this is "normal'. I compare the 603 endine with a (slow) jet engine - it needs time to wind up. Once it hits 2600 RPM, it takes off. I assume that the turbo starts making a big difference at this point. Also, the trans is a little slow to kick down. That's why in city traffic I keep the trans. in 3od gear, for faster pick up. (According to the speedo, you can do 84 mph in 3od! Check out your max. shift points on your speedo.) And, no, I don't max out the rpm's. Hope this helps. Your engine seems normal to me.

P.E.Haiges · #14 05-12-2003, 10:50 AM

PaulH,

Where did you get a '87 300SDl with only 40K miles?

It looks like its just a characteristic of the accelerator pedal and linkage design in the 300SDL. If I didn't have a 300SD I might not have noticed how stiff the 300SDL padal is.

Maybe I could find a linkage return spring that isn't as stiff.

P E H

rivermasternc · #15 05-12-2003, 05:05 PM

PEH:

AFTER checking to make sure all is in order with your accelerator linkages, clear ALDA boost signal line, clean overboost sending unit, start thinking about the ALDA adjustment. The factory settings were much leaner on the newer cars for emissions reasons. There's plenty of information in the forum on ALDA adjustment. Most of what I've read indicates a 1 to 1.5 turn on the screw to bring it up closer to the older model performance.

The ALDA adjustment will allow more fuel to the engine sooner. Over adjustment will cause the passing of unburned fuel (black smoke) and eventual blockage of your oxidative cat.