'83 240D throttle linkage - PeachParts Mercedes-Benz Forum

Pete240D · #1 02-24-2008, 11:58 PM

Just bought my '83 240D and am finding I have thottle linkage problems (shifts early on accel. with good vaccum at transmission). I have found a worn plastic bushing on the linkage (aft right side of valve cover) which a vertical shaft goes down and into the intake manifold (name ??). I am going to replace the bushing (will have to get new bushing from MB I'm guessing). I have also found that the linkage stops are set at full throttle to where the pedal stops approx. 1/2" before contacting the kick-down switch. I guessing someone has played with the linkage before. The manual I have says to have a dealer do the adjustments due to special tools and other resources, or can it be done by other means? I have not be able to find procedures for adjusting the thottle linkage, are there any available or is this a MB secret?
If my discriptions aren't clear, I can take pictures.
Thanks,

jkoebel · #2 02-25-2008, 12:32 AM

I think the FSM has the lengths of the linkages, which can be adjusted somehow. Probably by screwing them different ways.

I'm not sure, though...I have the same worn bushing on mine, but the linkages were adjusted by my mechanic to be more responsive.

t walgamuth · #3 02-25-2008, 06:46 AM

The links each have ball sockets on the end that are threaded. they have lock nuts that hold them in place. YOu just loosten the lock nut and pop off the socket from the ball and twist it to achieve the desired length, lock it down and lube the socket with a little axle bearing grease and pop it all back together. Lubing all the balls is one of those things I always do when I first buy a new used benz.

Tom W

JimSmith · #4 02-25-2008, 11:05 AM

Have someone in the car press on the throttle pedal while you observe the mechanical linkages. The pedal movement is converted to a shaft twisting motion at the firewall, where the twisting shaft extends forward through a coupling supported by the bracket coming off the valve cover. Not sure about the details of the automatic transmission model, but on the manual transmission models, the coupling loses up to 50% of the rotation travel when the rubber element disintegrates and disappears. This makes the first half of the throttle pedal travel nearly meaningless, and makes the last half of throttle travel on the injection pump unavailable. I tighten this connection up by inserting sections of popsicle sticks between the male prongs and female slots on the coupling, then use baling wire to grab and hold the inserts in place. I also typically wrap the sticks in electrical tape to take up the last bit of slack. This works for several years before the sticks just fall out and you suddenly have no throttle response.

I have not been able to get the new coupling parts from my local dealer, so I rely on the sticks. Have been doing this on two cars now for more than 12 years. Jim

Pete240D · #5 02-25-2008, 11:47 AM

Thanks for your responses! I understand how to adjust the linkages, what I'm looking for is, to what length are they adjusted? As for the bushing, I guess I may have to dig though a few "yards" to find it.

t walgamuth · #6 02-25-2008, 11:54 AM

I don't know but I would adjust til i got full throttle and zero at idle.

Tom W

JimSmith · #7 02-25-2008, 12:20 PM

I have never had an automatic transmission equipped W123, so I don't know anything about those details. However, I have never had the linkages "go out of adjustment" and would be leery of dorking around with changing the lengths of the links in this Rube Goldberg arrangement. I think there is something specifically broken, worn out, or missing that adds play to the system that eats up the travel of the actual injection pump throttle lever.

Don't be tempted to "adjust" the linkages to take away this play, as it is unlikely that this even possible without adversely "adjusting" the idle position or some other feature of the system. I very much doubt someone purposely set the lengths of the linkages wrong at some point, and they don't change length on their own, from the factory. Yes, the ball and sockets wear and you get some play, and this might be "adjusted" out, but we're talking about tenths of an inch here. Any more and the balls will fall out of the sockets, or bind up. Find the worn or broken or missing part, and replace it, first. Jim

kerry · #8 02-25-2008, 12:32 PM

On some 240d's, there is a butterfly in the intake. Perhaps the rod you refer to controls this butterfly. (I thought they had disappeared by 82). On my 77 300d a rod goes down, past the intake and attaches to another rod which goes back to the transmission. It's the equivalent of the Bowden cable in my instance (I think). So if your rod is like mine and it's movement has changed because of a bad bushing, I think it would effect shift points.

Pete240D · #9 02-25-2008, 11:18 PM

Thanks all! Someone has definately played with the adjustments I'm thinking due to the linkage hitting the stop before the pedal comes close to the kick-down switch. Also, today while driving (during city rush hour.....Opps!!) one of the links unscrewed itself from the ball joint and it only had two threads holding it. In all my aircraft rigging experience, I know there should definately be more. Looks like I'll be making an appointment with a MB dealer to have it all corrected. Thanks again!!

hangit · #10 02-26-2008, 09:08 AM

I don't know if you're linkage lengths are out of specs, but did you check the vacuum connections and the plastic control arms mounted on the valve cover? I had the same shifting problems which were corrected by installing new plastic arms. Go to www.dieselgiant.com for the DIY pictorial.

John