1982 240D throttle linkage sticks - PeachParts Mercedes-Benz Forum

atombaum · #1 11-29-2006, 10:58 AM

For about 2 months, the foot pedal for the throttle has been sticking. I have removed the foot pedal to verify everything is clear under it. I have inspected the linkages on the engine side. I found a bad plastic bearing at the part that screws into the firewall. Part number 123-300-13-40. Unfortunately, that did not fix it. Has anyone had this problem? It happens when starting from a stop or at up to about 45 mph. It feels like the pedal gets stuck about half way down. Have to release the pedal and push it down again. As you know, the pedal has to be mashed to the floor to get it to go. Any leads appreciated. Do I need to start looking at the linkage under the driver's kick panel?

rrgrassi · #2 11-29-2006, 11:17 AM

Quote:

Originally Posted by atombaum

For about 2 months, the foot pedal for the throttle has been sticking. I have removed the foot pedal to verify everything is clear under it. I have inspected the linkages on the engine side. I found a bad plastic bearing at the part that screws into the firewall. Part number 123-300-13-40. Unfortunately, that did not fix it. Has anyone had this problem? It happens when starting from a stop or at up to about 45 mph. It feels like the pedal gets stuck about half way down. Have to release the pedal and push it down again. As you know, the pedal has to be mashed to the floor to get it to go. Any leads appreciated. Do I need to start looking at the linkage under the driver's kick panel?

Have you checked everything under the hood, and greased the ball and socket connections? Also, did you do any work on it prior to it sticking?

Biodiesel300TD · #3 11-29-2006, 11:21 AM

Definetly check, clean, and lube ALL the linkages and pivot points under the hood. You might also try lubing up the point there the linkages go through the firewall.

Johnhef · #4 11-29-2006, 11:37 AM

ditto on that. clean and lube everything that moves when you press the go pedal.

Stevo · #5 11-29-2006, 11:43 AM

You have checked too see that the return spring is in place that is attached to that horizontal bar running along the fire wall?

sokoloff · #6 11-29-2006, 01:57 PM

Recommended lube is ATF.

Len

Ken300D · #7 11-29-2006, 04:01 PM

The pedal moves along a ball and rod bearing arrangement under your foot. This needs to be lubricated. If the car has sat with moisture in the carpet, this rod may have rusted or have a rust spot.

You'll need to remove the pedal completely to assess the condition. There is a press-fit plastic plug pushed into the bottom of the pedal. When that has been removed, the pedal can be raised, pulled forward, and then pulled off the interior linkage rod. You'll see what has to slide smoothly to keep the pedal working properly.

Here, I would use a light lithium grease, not ATF, due to the carpet.

Ken300D

atombaum · #8 11-29-2006, 06:14 PM

Wow - quite a few really good suggestions, this is quite an active group! I only wish I have not checked all those things already. I am aware of how the pedal works and fits. Have had it apart, cleaned, and lubed that sliding hole part with white litium grease. And I know about the white clip part. All clear there. I have used the "recommended" ATF on the ball and socket joints up front too. Do that about 3X per year. There is no moisture on the floor, no grunge under the pedal, everything seems to be nice and loose except when I get in the car and put my foot down. It feels like it's binding or getting caught on something. No, no work was done prior to this happening. Have NEVER been able to get it stuck by pressing down with my hand (figures). Had my wife pump the pedal while I watched the linkages and, you guessed it, nothing seen or experienced. Taking some time off work, so maybe will enjoy the 65 degree weather and look closer on the cabin side tomorrow. Got to verify that return spring. Have not seen how it's put together or what it's connected to. Maybe something is getting caught. Again, thanks for all the replies. If you think of anything else, let me know.

atombaum · #9 11-29-2006, 06:20 PM

Quote:

Originally Posted by Stevo

You have checked too see that the return spring is in place that is attached to that horizontal bar running along the fire wall?

Yes, that spring is working well. Plenty of pull on it. Table 30 in the little black parts book shows some parts that I need to check out further. I think those are on the cabin side.

300SDog · #10 11-29-2006, 09:11 PM

Check the linkage under the hood directly next to the injector pump. Is there a small black shock absorber /dampener attached to the linkage there? If so then pull it out and try driving the car without it.

Here's the story behind the throttle linkage shock absorber/dampener that arrived very late in 240D lore...... Somebody back in '82/83 *****ed about engine vibration being channeled back through throttle linkage and through the pedal to their foot while mashing the pedal to the floor, can you believe it? Purists will recommend you replace the tiny little shock absorber/ dampener with brand new OEM $30(?) parts from the dealership. DieselDog says hunk it and throw the worthless device into the trash instead.

atombaum · #11 11-29-2006, 09:49 PM

diesel dog: thanks, will check it out tomorrow.

Stevo · #12 11-30-2006, 12:41 AM

Quote:

Originally Posted by 240Dog

Here's the story behind the throttle linkage shock absorber/dampener that arrived very late in 240D lore...... Somebody back in '82/83 *****ed about engine vibration being channeled back through throttle linkage and through the pedal to their foot while mashing the pedal to the floor, can you believe it? Purists will recommend you replace the tiny little shock absorber/ dampener with brand new OEM $30(?) parts from the dealership. DieselDog says hunk it and throw the worthless device into the trash instead.

Interesting. I heard the "little shock" was to keep the RPMs from dropping fast which was supposedly to improve shifting, especially between first and second. I have noticed that my "85' " with the shock does shift nicer than my "79". I'd like to put one on the "79" and see if theres any difference. I've never noticed any difference in engine vibration being channeled back through the throttle linkage with or with out the shock.

300SDog · #13 11-30-2006, 02:51 AM

Oh no, not you again with your 5-spd 240's...... What you're sayin never occurred to me but you might be right it was designed to accomodate those who have no interest whatsoever in feathering the pedal manually in between shifting gears.

Dang it saddens me to reconnoitre that matching engine rpm to driveshaft speed and walkin the tranny through shifts, say especially while floating straight-cut gears of trucks'n operating tractors in general has become a lost art.

But then evolution of automobiles points to deliberately removing the driver from the driving experience, dont it?

t walgamuth · #14 11-30-2006, 04:28 AM

yep

i stiill will occasionally just stand there and listen to a semi going through the gears. a good shifter has a wonderful sound!

tom w

JimSmith · #15 11-30-2006, 09:17 AM

Under the bracket that supports the linkage from the valve cover is a three-pronged mechanical joint. One of the prongs is a round peg that fits in a bearing sleeve so the assembly pivots at that point, while the other two are like fork tangs, that fit into slots in metal yoke, that is covered with a bonded rubber material. The rubber material will de-bond after time and disappear, eventually. Anyway, without the rubber there, or without it bonded to the metal, there is a substantial extra amount of play at that joint and potential for things becoming misaligned. I have used popsicle sticks wrapped in elecrical tape to take up the slack and keep the system aligned. If this is your problem you will also find you are missing the last third or so of throttle travel at the injection pump, which means once the system is good and tight, the throttle response improves drastically. Good luck and I hope this helps. Jim