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Old 01-06-2010, 10:15 PM
LJetronic LJetronic is offline
German car addict!!
 
Join Date: Jul 2008
Location: New Orleans, LA
Posts: 27
86 sdl erratic shifting

My sdl with >300k miles and unknown history with the tranny was shifting rough when purchased about a year ago. It wasn't bad, so i left well enough alone until i came upon a spare injection pump with vacuum controller. I swapped the vacuum controller, just on a whim, and the tranny began to shift much softer and more appropriately with relation to accelerator position. Over the next few months of driving, the tranny began to flare between 3-4, especially under heavy throttle, so i'd been taking it easy. Most recently, i drove the car on a 1000 mile round trip and it did well, except occasionally when exiting the freeway and decelerating on overrun, the tranny would sharply downshift from 4-3 and would not upshift into 4th unless the selector was moved to neutral for a moment and then back to drive, then it would behave normally. It did this 3 times during the trip, and it only occurred after extended highway driving. Now that i'm home, this has been happening more and more frequently, in fact, it does it more often than not, just running around town with no extended highway speeds. Is there a common cause for failure to upshift from 3-4 and a tendency to downshift from 4-3? The other shifts are pretty good, maybe a bit soft, but certainly acceptable. SHould i be looking for a replacement valve body? or is this beyond that point now? Any advice would be appreciated!
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Patrick Frye

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1986 300sdl
1982 300td

Gone but not forgotten:

76 240d
80 300td
81 240d - my first mercedes
81 300d
81 300sd
82 300td
82 300sd
83 300td
89 300sel
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