This is concerning only cars with 722.3/4 in our case 722.4xx transmissions or any 94-96 W202 and most likely does not apply at all for the 722.6 (97 on).
So ever since I bought the car (last year with 138 000miles) when shifted in reverse I would hear a slight hissing sound and it would take 2-3sec to engage reverse gear. Once engaged it would reverse fine with no slipping.
I don't know the history of the transmission but I did change the oil and filter with mobil full syntetic transmissoin oil at 180 000miles
at about 188-190 000 the reverse was still working the same way but there was a rattling sound when going in reverse. For some reason I thought this was ok and normal
So at 196 500 I put in reverse and it wouldn't engage - if the car is on flat surface it would still go backwards just with alot of slipping like if you put you car in reverse and don't push on the gas it will reverse on its own as long as its going on flat or downhill but when going uphill you would press the gas to make it move at all... Well on mine pressing the gas wasn't doing anything so it was basically slipping and would engage only once in a great while and run absolutely fine in reverse when engaged but it wasn't happening often. The oil was still clean and it was going perfectly fine forward.
So I drove for a few more miles (more like a 1000miles more) like that and realized that it's a pain in the ass since I usually have to use reverse 20-30 times a day sometimes and it's not always on flat surface and also if it starts snowing i won;t make it at all.
So at 197 750 The transmission 722.423 was going to come out. But before that I went to the junkyard and found a 93 190E with a 722.408 transmission with I don't know how many miles since the cluster panel was taken already and everything seemed in great condition except the front flex disc which was destroyed so I figured the transmission is fine and the flex disc is why it ended up in the junkyard (really stupid reason to give it up if you ask me it was a beautiful car). Any way.. a few hours later the 722.408 out of the 190E was in the trunk of my car and on its way to the garage.
WILL IT FIT???
only differences the transmission mount on the 190E is different so there was two options:
1. buy and use a mount for a 190E which attaches in a different way to the transmission but attaches in the same way to the body of the car
2. Exchange the rear cover of the transmission which is held by 8-10 13mm bolts and also the output flange needs to be taken out and put back in.
So I did the second option. and got a new mount for w202 and new flex disc since mine turned out to be shot although I couldn't tell it was shot untill i actually had it out of the car.
Anyway a few hours later the transmission was in with new oil and filter -some adjustments of the bowden cable and modulator were done and the car drives just fine now. The only issue that I am having is that sometimes it will jump from 2nd to 4th, not very often though but just to make sure it doesn't do it I keep the lever in 3 and when it does shift 2nd to 3rd i then put it D and it works great and doesn;t bother me. I guess that transmission is not perfect but hopefully will last for a while.
currently the car is 199 400 so it has went about 1700miles with it.
I also wanted to mention that it seems possible to put in a 5 speed manual out of a 190E in the w202. It will take some more parts though like pedals, clutch pump, and front half of the drive shaft since the transmission is shorter then the automatic that's why the drive shaft is longer. Also the mount mounts forward and i saw that there is holes where the bolts go on the w202 chassis.
So many of you probably had the same problem with slow engaging reverse and maybe no reverse at all after a while and you wounder what caused it.
I have a transmission repair manual and for reverse gear slipping it says that it is usually caused by B3 piston lip seals. Now the B3 piston is in the front of the transmission so there is no way to check it out with the transmission in the car.
With the transmission out of the car and nothing to loose I took out the 10-12 not sure exactly how many bolts (13mm) out and pulled out the front cover. I found some very interesting stuff:
transmission with the front cover removed
Everything looks fine here.
B3 piston. Notice the 20 springs and the spring plate on the side (it was broken in two and there was those pins that guide the springs which was broken off too)
this shows better the return spring plate broken in two with some of the pins thorn off and some of the springs being damaged too.
There is no question... this is what was making the rattling noise when going in reverse. And this is probably why it stopped engaging at all.
this is the front cover with the B3 piston removed. It looks just fine.
This is the back side of the B3 piston. I circled(it is barely visible) a part of the lip seal is missing. I am pretty sure this has been missing for a very long time and it is what caused the transmission to take 2-3 secounds before it engages. There was also a little crack in the piston itself which is not visible on the picture.
Why did this plate break? I don't know. All the little pins that guide the springs were there so there is no broken off parts that went into the gears.
I really should have taken more pictures but I had no helper and my hands were really greasy all the time.
Anyway seems to me that the transmission is easily fixable. It should just need a new return spring plate with springs and maybe new b3 piston and defenatly new lip seals for the b3 piston.
The junkyard (picknpull) charged $130 for the transmission which 30 is core fee but I am not going to bring my transmission back. Instead I have found a 94 C280 with bad transmission not sure what they did to it but it won't go forward or reverse and it has a really nasty grinding noise but other then that seems to be a good car and I might be getting that for $1000 and fixing my old transmission and putting it in. If I do it i will report the results here in this post.