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  #1  
Old 02-01-2012, 01:28 PM
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W126 - 300SD - Throttle Linkage Adjustments

My car was "sluggish" seemed like it wasnt getting full throttle....After looking at some posts and a helpful video someone posted, I determined this was correct, I was not getting full throttle...

The data sheet from the FSM (too big to attach) for the 81-85 300SD , was somewhat helpful, but my car is a 1982 with an 85 engine and does not have a transmission pressure rod as depicted in this FSM data sheet. Also there was no way some of my connecting rods would be as long as is specified in this sheet while still allowing the cam roller to rest in the throttle closed position.

Here's a pic of the linkage at WOT before


Here's WOT now


The problems I see now is that I have "play" in the pedal before the connecting rod to the IP is actuated, and the kickdown button is not depressed when the pedal is to the floor...what is the kickdown button connected to anyway??
Here is the throttle linkage at idle position (where it's supposed to be?)

and this one shows the "play" this is where the cam roller is when the rod to the IP starts to move


Does anyone have any suggestions? or info?
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1985 300CD Silver/Blue H&R Suspension (Sold, still cryin over that)
1982 300SD Silver/Blue '85 OM617 (Sold)
1982 300D - Blue/Blue (Sold)

Last edited by SpecialDelivery; 02-01-2012 at 01:36 PM. Reason: didnt see the pdf attachement
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  #2  
Old 02-02-2012, 02:43 PM
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First make certain that the accelerator pedal can travel far enough to depress the kickdown switch (which downshifts the transmission electronically) With a helper pressing the accelerator, look to see if there is more travel available at the IP There is a stop. Also look for loose linkage. A bunch of loose linkage tolerances add up to not full travel, but you can adjust the slop. The pedal has to go all the way to the floor, and the linkage at the IP has to go all the way to the stop.
We can go from there.
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  #3  
Old 02-02-2012, 03:05 PM
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it does, I made some more adjustments ( after realizing I was looking at the wrong info in the FSM ) the pedal does go to the floor and clicks the button, when it touches the button the linkage seems right...I think I got this spot on...trouble is if I give the car that much throttle it will flare it's self to bits....the throttle is (I THINK) right now, when I get the car on open road in 4th I'll test the kickdown. I just put a multi meter to it and it shows infinite till I push it and then about 35ohm when it's engaged.


Thank you for responding!
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1985 300CD Silver/Blue H&R Suspension (Sold, still cryin over that)
1982 300SD Silver/Blue '85 OM617 (Sold)
1982 300D - Blue/Blue (Sold)
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  #4  
Old 02-02-2012, 03:10 PM
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OK Good, there is a vacuum bleeder attached to the IP with a vacuum line (black) going to the transmission. at WOT the vacuum should be low 0-4 inches maybe, at idle should be 14-18 inches. If at WOT the transmission is getting 14 inches of vacuum, it thinks it's just casually accelerating and it will flare,,, If someone bypassed the vacuum bleeder and hooked up vacuum directly to the source, you'll get this type behaviour.
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Old 02-02-2012, 03:33 PM
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bleeded...vcv..its putting 11 to the trans at idle and 0 at WOT, 6 with the lever 10mm off the stop pin
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1985 300CD Silver/Blue H&R Suspension (Sold, still cryin over that)
1982 300SD Silver/Blue '85 OM617 (Sold)
1982 300D - Blue/Blue (Sold)
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  #6  
Old 02-02-2012, 04:42 PM
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OK the flaring then could be cause by a bad vacuum modulator at the transmission, or it could be transmission itself is tired.
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Old 02-02-2012, 04:44 PM
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maybe perhaps a clogged transmisison filter and it's sucking up air in there. Once in gear, Thre should be no flaring, if there is, then is internal to the tranmssion, I would think.
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Old 02-02-2012, 04:56 PM
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Yes the fluid and filter are fresh, and I put "lube guard" in it...which is the only one my mechanic buddies recommended.

The modulator I dont know about because it does hold vac, but with it turned all the way up I'm only seeing 25psi. I'm thinking the pin on the inside might be worn down? So I'm thinking of just replacing that and doing a spring kit from Superior Transmissions.
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1985 300CD Silver/Blue H&R Suspension (Sold, still cryin over that)
1982 300SD Silver/Blue '85 OM617 (Sold)
1982 300D - Blue/Blue (Sold)

Last edited by SpecialDelivery; 02-02-2012 at 04:57 PM. Reason: clarifications
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  #9  
Old 02-02-2012, 05:02 PM
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Did the flaring start after the fluid flush? How was the fluid in the pan, any grit? If it was nice and clean, chances are someone tried that already, and there's no telling what was in the pan on the first flush.
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  #10  
Old 02-02-2012, 05:06 PM
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How does the car shift with the black vacuum line disconencted? It should shift harsh. Possibe slow reacting vacuum modulator, as in it's gunked up inside. Does it flare when it's in gear (not inbetween shifts) but if it's solidly in gear on the freeway going 50 mph and you floor it, there isn't any flaring there, is there?
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  #11  
Old 02-02-2012, 05:57 PM
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no the shifting flared before the flushing, the fluid looked decent, I changed it and the filter anyway...pan was fairly clean. if i disconnect the modulator it still flares, just only in between 3-4, it was disconnected when I got the car. When I take the cap off the modulator there some brownish fluid...not trans fluid, it looks like rust. while underway if I stop the pedal to the button and click it nothing happens in the trans, the car gets more fuel and takes off but I do not believe it is downshifting
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1985 300CD Silver/Blue H&R Suspension (Sold, still cryin over that)
1982 300SD Silver/Blue '85 OM617 (Sold)
1982 300D - Blue/Blue (Sold)
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  #12  
Old 02-02-2012, 11:20 PM
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Quote:
Originally Posted by SpecialDelivery View Post

The problems I see now is that I have "play" in the pedal before the connecting rod to the IP is actuated
Here is the throttle linkage at idle position (where it's supposed to be?)

and this one shows the "play" this is where the cam roller is when the rod to the IP starts to move


Does anyone have any suggestions? or info?
This situation is normal. The very first 1/4" of pedal travel does not move the rack. This is solely the movement of the Bowden cable and allows the transmission to do a 2-1 downshift prior to adding any fuel.

It does seem abnormal when you first observe it, but...........have no fear.........it's fine.

The problem with the linkage not advancing the IP lever to the stop needs to be addressed, however.
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  #13  
Old 02-03-2012, 02:59 PM
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Brian when you said "The problem with the linkage not advancing the IP lever to the stop needs to be addressed, however." are you seeing something I am not? From what I can tell the IP lever is hitting the WOT stop.

Thanks for weighing in on this, it seemed right after looking at some other pictures and videos I've seen around
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-SpecialDelivery
1985 300CD Silver/Blue H&R Suspension (Sold, still cryin over that)
1982 300SD Silver/Blue '85 OM617 (Sold)
1982 300D - Blue/Blue (Sold)
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  #14  
Old 02-03-2012, 03:12 PM
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Quote:
Originally Posted by SpecialDelivery View Post
Brian when you said "The problem with the linkage not advancing the IP lever to the stop needs to be addressed, however." are you seeing something I am not? From what I can tell the IP lever is hitting the WOT stop.

Thanks for weighing in on this, it seemed right after looking at some other pictures and videos I've seen around
I am simply responding to previous comments where you have stated that it is not getting "full throttle". If you can tell that it is hitting the stop, then please disregard my comments related to that.
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