(posted on benzworld.org as well)


Hopefully someone can point me in the right direction with this. Ive been searching and gathering info on what this could be but the more I look the more I get confused.

This is my Girlfriends car first of all. It is one of the greater achievements of german automotive endeavors...the 1978 300CD. Transmission is the 722.118 four speed, four bolt.

In the past there have been minor slippage between 2-3 (mainly uphill) and some hard kickdowns (again, mainly on hills). Nothing I would consider too too awful. Up to last week the car was running fine then within the span of 3 days the GF reports that the transmission started slipping while in drive on flat stretches of roads. Now the slipping is constant to the point where the car seemingly has no forward gears.

The car will move forward, but its almost as if the gears do not engage. As if the forward motion is just through the shear forces in fluid of the torque converter. Pressing the accellerator doesnt yeild a shift or any faster forward momentum. The car will slowly build speed, but it might as well be accelerating off of idle. Reverse is perfectly fine, engages immediately and accelerates like, well....like its in reverse.

Ive searched around an found lots of references to mysterious things like the B2, B1 valves, K1 spring, etc etc. Most of this though seems to be for the newer 722.2-3 transmissions. I did pull the B2 valve in the transmission but nothing seemed damaged(no broken spring as seems to be the case with the 6-bolt transmissions).

Vacuum is also a culprit mentioned. This car however, has no vacuum box on top of the engine. The transmission also does not have a vacuum modulator on the passenger side of the transmission as shown on this page 722.118 Transmission Adjustments

There is only a large bolt where the modulator should be. As a matter of fact I cant find a vacuum line anywhere on the transmission. Is this normal?

Ive also found a couple pages on the transmission itself like so.. 4 Bolt Pan Not too helpful though as there isnt a glossary of parts.

This has been the best reference that I have found so far about the troubles of the 722.118 transmission, a post here from a couple years back..complete with pictures of what I should be looking at (although theres the vacuum modulator thats not on this transmission) 722.118 transmission B2 servo/piston - ShopForum

One thing that I have to redo is completely remove the B2 piston and look at the piston bore as this other fellow had. I neglected to do this the first time when I looked at it. I dont have compressed air at my disposal, whats a good way of getting that piston ring past the groove for the C-clip?

I also removed the valve body and noticed a couple things. A lot of wear marks on some of the tabs of the valve body housing.


wider shot

far side


I am not sure if these are normal happenings or ....something else

Also, what is this (very)worn metal tab and why is it pressed into the band here?



I notice in the link above the pictures show the same metal tab but it isnt worn or contacting the band..normal or....?

Anyway, I have been chasing my tail on this and if someone has an idea as to what direction I should go in it would be greatly appreciated.

Gavin