Loosing reverse or something less serious?
 

I have been loosing reverse on my car, but why is it that in the morning on a cold start the reverse is fine, but after the car is warm it doesn't work? Am I really loosing reverse or is there something else going on?

I hate to be the bearer of bad news.......

Dammit! Does that mean I'll lose all the other gears too?

No. Typically you only lose the reverse gear, not forward too. If you are lucky, doing a filter and fluid swap will sometimes be enough to cure the problem...if it has been awhile since doing so.

I am the unlucky one then. I did a filter and fluid change along with new pan and gasket within the past 5-6 months....unfortunately I did not know (and still don't know) where the torque converter is or how to drain it, so I just flushed my transmission 4 or 5 times hoping that whatever was in the torque converter was replaced with the new fluid.

Doing the torque converter is a good idea because the old fluid in there is just going to contaminate the fresh stuff, was there any particles or crud in the old transmission fluid?

nope, no particles whatsoever

fluid is thicker in the mornings so it grabs easier, once warm and more viscous it fails.

....but didn't we already go through this in your last thread?

yeah, something about B3 clutch someone mentioned, but sometimes orr works

Sounds to me like a blown reverse piston seal. When cold it fills up a little faster than it leaks out, which then reverses when the fluid gets warm. But it doesn't really matter, seals or clutches - the transmission has got to come out either way.

I watched a video of someone replace a piston of some sort....it looked pretty simple. maybe it was a K1 piston? anyways, could it be a quick fix until I get it rebuilt?

K1 shift kit has to do with shift quality for forward operation. You may be thinking of B2 piston repair, which can be on car, but that too is forward operation. I've not ever heard of a on the car fix for the reverse problem. You could try one of those slipping clutches transmission additives - can't see that you've got much to lose.

Well I think it was a youtube video.....the part looked like the inside of a pen (my closest analogy if it) where there was a spring, a plastic piece, and maybe something else where he removed a small 4 screw (flat head) plate and took out the old spring and replaced it with the new one. But no worries, I'll start saving for the rebuild. I don't think I've tried an additive, can't remember, but I guess its worth a shot until I can get the rebuild. How much does a typical rebuild cost.....assume that most gears and seals will be done?

That is the K1 Spring kit. Just helps with shifts, not reverse issues. The Piston is a whole different animal.

I had the same problem with my 90' 300e. It's a common failure on these transissions. I ended up having the unit rebuilt. It only had 200K mikes on it, don't know why it failed.

-Jim

I hope you are kidding. 200K on an original transmission (and just losing reverse at that), is very good compared to any other average domestic or foreign car. It's pretty good for a W124 too. 180K on mine and reverse is still snappy.

Hmmmm...I feel fortunate then that mine is at 275k and the reverse just started to go :)

Well the odometer broke at 193K so I really have no idea how many miles were on it, but I figure it's in the 200K range. I did valve stem seals on it cuase it kept fouling #3 and took it on a 11 hour drive to W Va. and back with 5 poeple + luggage and except for being a little under powered (2.6L) it went up and down the mountians with the air on without a hickup. Then we gave it to my brother inlaw last summer and he has been driving it ever since. It just wants to go forever.

-Jim

i have the same issue on my 89 300ce,it had a delay going into reverse,one day the delay got longer and longer,to the point i have lost my reverse altogether,a mercedes specialist told me just from describing it,it sounds like the reverse piston has a hole in it,its not an easy fix,the tranny has to come out,he was telling me i need a complete overhaul for $2,000.00, i wanted to know why he couldnt just fix the reverse issue then he just hung the phone up in my face,imagine that,they think we are all loaded with money just cuz we own a mercedes-benz.im waiting on another shop thats backed up for like 1 month, he will diagnose it for free,then tell me if he can just fix the reverse,all my forward gears shift fine,the tranny fluid is brand new and smells very clean,blood red,i added lucas oil tranny conditioner and it didnt do anything.goodluck with your situation,its a real pain having to push the car and cut the wheel to get her to turn around,but if you park on a slight incline the car will roll backwards then you can shift into drive and it will be fine.

I think he's saying you've blown a reverse piston seal, which sounds right. It's just a couple hours of work but R and R the transmission is about six hours. Depending on your miles and plans it could be the wise thing to do. But nevertheless most shops don't want to do it - they want to do the full overhaul and you can't really blame them. They shouldn't hang up on you though - that's not a good sign.

Losing reverse intermittently ...
 

I have the 5-speed 722.5 auto box.

Cold, mine engages reverse normally.

Warm, it MAY not engage reverse; it just sits there but SOMETIMES will crash into reverse if I rev it high.

Hot, it usually engages reverse normally.

I aim to try a filter and box/torque converter drain and refill in the hope that might help.

I do feel somewhat pessimistic about this give the 230 K miles on the original box.

RayH