BenzWorld Junior Member
Date registered: Nov 2011
Vehicle: 1993 300sl
Location: Warrenton, va
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300sl transmission 4th gear shift?
1993 300sl 24V with 117K miles. Corrected all the items on my "fix list" except one - the transmission.
Symptoms: Transmission shifts hard, and 3rd to 4th-5th at weird shift points.
Accelerate under normal speed, starting in 1st, 1st - 2nd shift happens around 2200RPM, 2nd-3rd shift around 2200RPM, crisp and normal. 3rd runs up to around 4600RPM, hits 4th, and drops to 5th in another millisecond or so. Sort of misses 4th. Under harder acceleration, there is a bit of a "flair" on the 4th gear shift, then it goes into overdrive 5th. If I accelerate from 3rd to around 2500 RPM, and drop off the gas pedal for a second to decellerate, it shifts into 4th, then shifts to 5th. Still not quite normally, but with less wear and tear.
It's a 20 year old car, so I've been replacing all the rubber vacuum line connectors on the intake manifold, at the vacuum modulators in the electronics box at the upper passenger side firewall, and actually replaced the vacuum modulator and rubber connection on the transmission itself. Shifting has become smoother from the original set of symptoms, and engine runs smoother, but it still isn't shifting correctly. I replaced the transmission filter, filled with new fluid, and replaced the 1st gear shifting control plunger/spring per MB maintenance recommendation. No discoloration in the fluid, no "burned" smell to the fluid. None of these has solved the shift point problem.
Some internet searches suggest that the shifting point problem suggests that the transmission controller is the fault. Using my MB diagnostic analyzer (i.e. the pushbutton thingy) no "flashing lights" seem to be set when I look for diagnostic codes.
I'm running out of cheap fix options!
Before I spend $1200 on a transmission controller, has anyone else experienced these same transmission symptoms? How did you fix it?