Hi Everyone.

I'm new here - hope you guys can help with my problem...

My 1993 300E (W124) has suddenly started changing up very early. It will pull away in 2nd, change to 3rd and then to 4th before the speed even reaches 40kph - no matter how much hard (or soft) I press the accelerator. It will also not kick-down when pressing the kick-down switch at the end of the accelerator pedal travel.

Moving the gear selector to 3 changes the gear to 3rd, but moving it back to drive immedialety changes it back to 4th, even though I give it lots of accelerator. E-S selector switch is always in S.

Performance seems to be fine, other than a bit sluggish because of the higher gear and lower speed. Cruising at 120kph is normal. There does not appear to be any slipping.

I have read almost every post I can find on the bowden cable and then last night I took the car out on the road to adjust it. Well, after stopping about 25 times, adjusting a bit, and testing for about an hour, there is no change whatsoever! In fact, no adjustment (whether tightening or loosening the adjusting nut) has any effect. I definately have the correct cable because I found some pictures in the posts which show it very clearly.

Anyone have any ideas for me?

Mine is changing too late. I gased the pedal, and the change between 3rd and 4th gear went up over 6000 rpm, into the RED. Is the transmission going? Car has 220,000km/140,000 miles.

No more torque either..

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87' 300E champagne - Euro headlights and corners, 8-hole rims, 140,000miles/220,00km.

Before my problem above, my gears changed at exactly the marks on the speedo (|,||,|||) with the revs almost in the red. If yours are not slipping and change 'sharply', then I would say you may be able to get them to change a bit earlier by adjusting the bowden cable which lies between the transmission and the engine bay. Do a search on this forum for 'bowden cable' and you will get lots of info on this.

Trevor,
Welcome to mercedesshop.com
I am sure someone will be able to help out in this forum as the members here are great at providing excellent technical advice.
You have mentioned that your gears were shifting properly. when did this slack start to happen and when it did, was something changed right before it started to happen ?

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Whether you think you can or cannot, Either way you're right!. by Henry Ford.

Hi Benz300, how it all started:
I drive a 20km trip between small country towns each day. (Live in one town and work in another). On this particular day, I drove out of town and everything was good. When I arrived at my work town and had to pull away from a stop, I noticed the early gear changes. No bang, no whine, nothing!

As I said, I have adjusted the transmission bowden cable - no change at all. Last night I climbed under the car and checked all vacuum lines as well as the point where the bowden cable enters the tranny and it seems to be firm (attached). I then checked the vacuum lines in the engine bay and also found nothing. I checked again while driving this morning and I can manually select all 4 gears. All change nicely, just far too early and almost independant of the throttle position. No matter how slow or fast I pull away from a stop, they change at the same point!

So, has anyone anymore ideas?

... as an update ...

This weekend I had a bit more time on my hands, so I lifted the air cleaner to get proper access to the cables, linkages and vacuum pipes. I noticed that the accelerator cable wasn't quite returning to its proper rest position and therefore not closing the microswitch (not sure what the function of the switch is). I lubricated all linkages and now it's closing the switch properly.

Apart from that, I can see no other problems. I inspected the vacuum pipes and they seem to be OK. The rubber ends are definately not brittle. So.... my original problem still remains! Help please!

Your model car has an up shift delay plastic actuator, which is part of the throttle valve, cable mechanism, this complicates the diagnoses.

Driving the car in the “S” mode should let the transmission shift later, if not then the problem can be, the actuator, cable or valve body related.



Adjust the cable as tight as it would go then drive the car at light and medium throttle, do not drive at WOT, you might damage the cable or actuator with a tight cable; if you still have early shift’s, remove the transmission pan, look at the throttle lever, it should be touching the TV plunger, if it doesn’t you have a problem with the cable or actuator. If it does

Have a helper move the gas pedal as you watch the movement of THE throttle lever. The lever should move the plunger " INTO" the valve body. The plunger movement should be the same as gas pedal movement, if it is the valve body is the problem.

Thanks for the detailed instructions C32AMG! Here's what I have done so far....

"Adjust the cable as tight as it would go...." I still had early shifts

"look at the throttle lever, it should be touching the TV plunger..."
Yesterday I drained the transmission and torque convertor and replaced the filter and gasket. I can see the throttle lever and what I presume to be the TV plunger. (not quite sure what "TV" means). The plunger sits on the side of the valve body and the lever is held up against its end by a spring? This plunger looked like it was sticking way too far out of the valve body and when I pressed it in a bit to check its movement, it sprung halfway in and stayed there. Looks like this is where it's meant to be? Presuming that this could be the solution to the tranny's problem, I closed up, refilled and tested, but there is absolutely no change at all.

I looked under the car again and noticed that where the bowden cable enters the tranny, there is a plastic end to the cable which is loose and was stuck up and out of the tranny. (wish I could draw a picture!) Is this meant to be loose? It looks to be like it is making the cable too tight, but I can't see what should be holding it in place. I'll try to take a picture but it's difficult to get in there. Any ideas?

I have the same issue with a 89 190E 2.6. Mine just started out of the blue. I am going to drop my trans and rebuild unless someone has an idea on what is causing it.
I have changed fluid, filter, modulator, vacuum line to manifold, and the rubber connecter with no change. I also lost the kickdown ability when this happend.
Anyone wanna throw there 2 cents in?

mghaz26, have you tried to adjust the modulator? That may be your solution.

Hey mghaz26, I'm so glad that someone else has exactly the same problem as my 300E has (Sorry). I also lost kickdown at the same time - all out of the blue!

Do you have any ideas on the plastic end to the bowden cable where it enters the tranny? You seem to have been under your car a lot! Did you check this - does yours fit tightly into the tranny?

This plunger looked like it was sticking way too far out of the valve body and when I pressed it in a bit to check its movement, it sprung halfway in and stayed there. Looks like this is where it's meant to be? Presuming that this could be the solution to the tranny's problem, [/QUOTE]





When you push the plunger into the valve body, you should feel a heavy spring tension and when released it should push/ spring back out of the valve body. The control pressure valve plunger (also called throttle valve) should not stay in the valve body, if it does the valve body needs rebuilding. You may have found the problem for your early shifts, no kick down and no 2nd to first gear kick down shift.

The round part of the cable goes into the transmission case, if you can pull the cable out of the case, you need a new one. The modulator in the 722.3, 4 and 5 transmission control shift feel not timing.

Thanks for the reply's. I didn't do anything today, but i will try these options 1st thing in the morning.

I will remove the transmission pan and inspect (maybe remove and clean out the) valve body. When i replaced the modulator i did not do any adjustment to it. I will try adjusting modulator pressure with my trusty mighty vac. My cable has spring return when i pull and release. So i hope i can resolve my issue with these options. I will take pictures and post any result good or bad.

Trevor the cable goes from the linkage to the passenger side of trans just behind where the dip stick tube mounts to trans.

Thanks C32AMG for the info. Yes, the plunger has a strong spring action when pushing it into the valve body and, on releasing, it springs back out, but only about half an inch. Is this far enough?

It looks like I also need a new cable then...

mghaz2.6, it will be interesting to hear what you find while inspecting the valve body - let us know...

First i tried adjusting the the modulator (3/4 of a full rotation). No change to the early shifting pattern. I tried the easy way first but i don't have that kind of luck.
I just got done removing the valve body and upon a quick inspection under sufficiant lighting i looked at the pressure control valve pushing it in, it had return pressure so i looked beyond the valve and noticed the was a plastic washer (spacer) around the shaft where it meets with the Govenor Booster Valve. Well it was missing a peice of it. I found a tiny peice of this plastic in one of the journals. I am going to open up the valve body and take more pictures early tomorrow. I will post Pictures as soon as i get my camera cable (before i split valve body).