Throttle linkage problem - PeachParts Mercedes-Benz Forum

EdmondsAve · #1 06-23-2007, 02:19 PM

Yesterday on the way home from work my car started accelerating poorly, and this morning it was hard to beep running....when i popped the hood, i manually accelerated it through the linkage and it revved fine, but when i hit the pedal, theres almost no tension and it only revs lightly unless i hold it down. theres a piece of metal behind the oil filter that has one spring attached to it (its in the shape of a V and has multiple holes in it). Did i break a spring or something? cause its obviously somewhere between the pedal and the linkage there....i need help cause im a courier and need my car to run by monday morning!

85 300Dt

carnut · #2 06-23-2007, 04:15 PM

Simply have someone depress the pedal while you watch the linkage from the firewall to the inj. pump. The pivot could have come apart at the firewall or the straight rod going from it to the pivot linkage just above the inj. pump could have loosened up. With the engine off, rotate the linkage at the pump by hand to understand where wide open throttle stops are located and then watch as someone depresses the pedal inside the car. It should be apparent whats going on and what needs adjusted/replaced. The spring goes straight up from behind the engine and is there for stiffer or lighter throttle pedal feel based on which hole you choose to use.

EdmondsAve · #3 06-23-2007, 05:38 PM

well that didnt help (i dont know much about this stuff as a whole), but thanks. i thought the linkage so i tightened it up only to have the car stay running while the key was off. It just doesnt go to wide open throttle anymore when i hit the pedal, but when i pull on the linkage, its fine, and revs up like it should. wtf is goin on? btw, you gotta give me more details, im fairly new to mercedes'

EdmondsAve · #4 06-23-2007, 05:46 PM

I think i found the prob.....at the end of the straight rod by the firewall, theres a rubber bushing or something, and its come apart and doesnt have enough resistance to pull the throttle. whats this called, where can i get it, and how hard is it to replace?? for now im gonna zip-tie the **** outta it.

carnut · #5 06-23-2007, 05:51 PM

Thats the pivot I spoke of. Check one of the vendors on this site. Also there are many at wrecking yards.

W123x3 · #6 06-23-2007, 09:03 PM

I have "rebuilt" that pivot point on at least a couple of W123 cars. The first time was during an out of town trip when we needed to head home on the weekend.

Find a short piece of metal or plastic pipe that the nylon cylinder will fit in snugly. Then JB-Weld that piece into the sheet metal bracket at the correct angle. One of those "temp" fixes lasted at least 3 years before I replaced it with a new one. Most of the ones in the U-pull yard will be shot unless they were recently changed. The hard white round stuff in the bracket turns to crumbling wax after 25 years. Never understood why it was designed the way it was. Anybody know why?

Stevo · #7 06-23-2007, 10:20 PM

Interesting linkage discussions lately. I have a 240D with the (123) "early" linkage that comes up from the other side of the engine and over the top of the valve cover. The pivot plate (is that what its called?) up under the manifold failed and was a bugger to get to, other than that its been allot less trouble than my later cars with all those rubber bits that fail. Far as I'm concerned they coulda stuck with the "early" heater controls too,

rant over

pawoSD · #8 06-23-2007, 10:45 PM

I think it was designed that way to provide additional vibration damping, so the pedal doesn't vibrate so much. I bet the gasser cars do not have a bushing like that.

Ken300D · #9 06-23-2007, 11:09 PM

My theory is that plastics technology wasn't as far advanced in the early 1980s, so the bushing is inferior to modern products.

I bought a replacement at the dealer for my 1982 300D. Much improved design. You should also have about the same results with the non-dealer sources. Here at the "Buy Parts" link above, for example. Find your vehicle, and look under "Fuel Delivery" and then "Throttle Bushing". You want the "Pivot Mount" part. I see they now have two styles - to me you'd want the one that looks like the OEM part, the more expensive one. (If they show more than one Pivot Mount for your car.) The cheap one looks incomplete - maybe its a partial assembly and you have to swap over a portion of your old one, I don't know.

If you need to be running by Monday, looks like you will need to take the temporary fix suggestion mentioned earlier.

toomany MBZ · #10 06-23-2007, 11:15 PM

I have a part or two that might work, yours for shipping charges.

EdmondsAve · #11 06-24-2007, 01:30 PM

When i was working on my throttle linkage yesterday, my vacuum stuff came loose, causing my car to continue running with the key off. the culprit line is a black line from the blue resevoir(?) on the drivers side fender than funs down in behind the engine. what does it plug in to? i need to fix it so i dont have to pop my hood 20 times tomorrow to shut off my engine!

Stevo · #12 06-24-2007, 04:23 PM

Quote:

Originally Posted by EdmondsAve

When i was working on my throttle linkage yesterday, my vacuum stuff came loose, causing my car to continue running with the key off. the culprit line is a black line from the blue resevoir(?) on the drivers side fender than funs down in behind the engine. what does it plug in to? i need to fix it so i dont have to pop my hood 20 times tomorrow to shut off my engine!

Would help too know what car you have, All the W123 shut off vacuum lines I have seen are brown.

MBeige · #13 06-24-2007, 11:24 PM

Look for the 10mm nut on the throttle linkage and see if it's loose Tighten it with the linkages at WOT (pull it back towards you while you're looking at it from the driver fender).