300E sluggish acceleration, with early gearshifts
 

1989 W124 300E 280,000 km's has all of a sudden has lost its 'power'.
Starts easily but when I put my foot down hard on the accelerator to overtake, it refuses to kickdown and upshifts much earlier than normal. Won't go anywhere near the redline in terms of engine revs. Checked the transmission fluid, it seems ok. Tried unplugging the kickdown switch, no difference, same symptoms.
Recently changed the spark plugs and air filter, car seemed ok when I test drove after plug and filter change.
Today whilst the car was at idle with the transmission in Park, I could hear a metallic clunk noise coming from the transmission area. It wasn't constant, just once in a while, I couldnt tell if it was coming from the transmission or further forward near the engine, because it was only once in a while. Couldn't hear the noise while driving. Only seems to be there at idle with the transmission in Park.
Gearshift seems smooth enough, although it changes gears way too soon. Seems almost like gear slippage, although the engine is not over revving, in fact it won't allow itself to be driven hard.

Any thoughts/opinions...

sounds like you have issues with the trans cable.disconnect from throttle linkage and pull on it to make sure that the spring in the trans is still good.if so you need to adjust it[by screwing out the white threaded nut on the cable] to effectively make the cable shorter.[they stretch with time and use]

300E still sluggish and upshifting way too soon
 

Thanks David,
As you suggested, I disconnected the cable and yes I could feel the spring still working at the other end. I re-attached the cable and then made a point of adjusting the cable so it was fairly loose (it seemed to be adjusted very tight to begin with) reconnected and test drove, but this made no difference.
Should the cable be tight or loose.?
I also made a point during the test drive of having the kickdown switch both connected, and then disconnected. (again no difference)
Does the vacuum modulator in the transmission have any affect on whether or not the transmission upshifts too soon.?

benzdriver737

Someone else with same problem, plus answers
 

Found this while searching for answers.....
Identical symptoms...


click on this link for more info:

http://www.peachparts.com/shopforum/showthread.php?t=120658

Problem fixed.
 

Took the plunge and removed the valve body and pulled it apart to find a broken spring in K2 accumulator.
I had the spring upgrade kit on hand so it was then a matter of fitting the new spring along with new teflon rings for the other accumulators that I had purchased in anticipation of doing this job.
Valve body channels had deposits of 'black gunk' and several of the valves were very 'sticky'.
Took me 7 hours to pull out the valve body, clean it and get it back together, refill with fluid and test drive.
Kickdown has returned, and now it shifts as it is supposed to.
First time testdrive it seemed no different, then I remembered that I had been messing with the kickdown cable and had left it with hardly any tension so it was very slack... Took up some slack on the cable and viola... gearshifts, kickdown, acceleration... nearly as good as new.
I just need to fine tune the new accumulator and all will be as it should be.
ATSG Manual is a 'must have' if you are thinking about this job. Also somewhere clean to work.