Auto gearbox changing too early

[TrevorC]

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. 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 3rd changes the gear to 3rd, but moving it back to drive immedialety changes it back, 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.

Anyone have any ideas for me?

[gtkriss]

sounds like your W124 tranny has a mind of it's own!haha.

I would start by checking your tranny fluid level.. top it off, or flush it if you have to.

This slippage between gears doesnt sound good, however there are 1 of 2 possibilites.

1. Your computer is messed up.. Someway some how, your car is over calculating the rpm from the engine and shifting early. Your best bet, get a scanner, run it, find some codes, (if any). Either that or check your computer stuff.. It's located behind your battery. Corroded, missing, not pluged in, etc.

2. Your internal clutch plates (i.e. inside the transmission) are wearing. this can be either to; age/wear/mileage or abuse. This is the big no-no that we wanna avoid cause then it would mean a new tranny or a rebuild.

[TrevorC]

Hey, Thanks for the reply!

I have checked the fluid level/color - all looks good to me. The box isn't actually slipping, just changing too early. I checked out the bowden cable last night, but adjusting it either way made no difference at all. I am therefore going to look at the other end of this cable (transmission end) to check that it is still OK down there. Am I on the right track?

Does my car have a computer controlled tranny? 1993 300E W124

[talonlover]

That struck me funny too. The 722.3 transmissions were controled by vacum. I would look for a vacum leak, but not only around the transmission, check the brake booster line also. I would agree with the service however. When is the last time you had a trans service? There may be some passages in the valve body clogged, MB makes some amazing transmission fluid(kind of pricey) that will really do wonders on a older transmission with problems. Check those two things and report back.

[TrevorC]

Yesterday I drained the transmission and torque convertor and replaced the filter and gasket. I noticed that there is a plunger which sits on the side of the valve body and a 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?

[TrevorC]

Well, problem is now solved:

Checked the governor - OK
Removed the valve body and found a bit of build-up in the oil channels which must have been blocked. Stripped everything, cleaned, installed a K1 spring kit and all's OK. Shifts like new!