'05 CDI transmission "shudder"
 

My recently acquired CDI is displaying a weird "shudder" right after it shifts. If I accelerate hard, it shifts fine and then starts to shudder when I let off the pedal. If I am accelerating or decelerating, it is fine. Only if it has a light throttle just to maintain speed, it shudders. It almost feels like a clutch that is slipping-grabbing-slipping-grabbing real fast. I am hoping it is something easy to fix, like a solenoid or something. I have plans to change the trans fluid and filter, but don't want to do it twice. Anyone have any ideas? I may try calling Marc at Sun Valley Mercedes Transmissions to get his opinion. Any ideas would be greatly appreciated. Thanks, Rich

Check trans mounts, before you get depressed with trans issues.


I've witnessed this same issue, in a friends car and it was the trans mount. Not a Cdi, but worth checking first.

I will check it tomorrow. However, it feels like something is amiss hydraulically. The car moves forward and back.

Are you sure the engine isn't missing out with light load? When I was having delivery valve issues in my SDL, it would have a soft "skip" up until ~1500 RPM. It definitely FELT like torque converter shudder at light throttle input.

I realize you have a CDI which is a very different system from the old IDI's, just offering a different avenue to look into.

Definitely NOT a missing engine. The engine is the smoothest and most powerful I have experienced in a sedan. It would also throw a fault code if any misfire has occurred.

You are on the right path to try changing fluid/filter first.

Do a search for RSN ( Rumble Strip Noise ) on some sprinter sites. The torque converter clutch may be dragging / being too aggressive causing a slip - stick - torsional vibration ( like being in too high of a gear in a standard trans )

The TCC on the 722.6 is modulated from 0 to about 98% lockup. When you are harder on the throttle the TCC isn't engaged as much so you don't feel the shudder.

A fix is to replace the TC with a spring release clutch. Changing fluid might not fix this. About the only additive I'd try is a friction modifier ( like posi traction additive ) called " Shudder Fixx " , it is made by " Lubeguard " Instant Shudder Fixx it is about $ 7 a tube. I've used this on many non MB cars and it works, as long as the problem is a TC shudder not a failing trans.

You are right on, and agree with Marc at SVMT. I changed the fluid today, and man was it gorse! I think it had never been changed. It was dark greenish brown. Using compressed air through the cooler line fitting, I was able to get 6.5-7 qts. out. There was just a very little grey fuzz on the magnet, so that is good. As suggested by Marc, I used cheap fluid and a new filter this time, and will change it again using synthetic. On the test drive, I noticed that almost all the shudder is gone. I would say about 80 percent, whereas it was horrible before (almost not derivable). There is just a mild shudder after the 2-3 & 3-4 shift. I am hoping another flush will get rid of the shudder completely. Worst case is I will try the shudder fix. Thanks, Rich

no ide if this would relate but I had a simular issue with my 99 e320. after months of troubleshooting, and even going so far as replacing the transmission (car started to drop out of overdrive etc) it turned out to be the computer in the auto shifter had crap spilled all over it. someones nice sugary hot beverage, couple cokes who knows. swap at new shifter in from a wreak and never another issue

That was the problem with my friends car lately (another thread), and yes, I replaced the shifter with one from his parts car. I doubt that is the problem here. The shudder is all but gone. I got a tube of the Instant Shudder Fixx yesterday, and that should fix it for good.

Hey rollguy, what cheap tranny fluid did you use? I am planning to do the same thing to flush the trans on my (also) newly aquired '06 CDI.

While performing the 2nd fluid change, you might want to consider dropping the valve body and replacing the conductor plate. There is plenty online about this issue...

I too would be curious to know what "cheap" fluid there is. If Sun Valley says its good I'd be inclined to trust them. I've been buying it wholesale from the dealer but its still quite expensive. Did fluid and filter when I got the car, and a quick pull of the drain plug and gotten 2-3 quarts out on two other occasions. But if there is a cheaper fluid I would like to try to get more out.

I bought a case of the 134 ATF made by Shell from an oil distributor locally in OH for around $70.

A bit of trans tune by seafoam helps in cleaning out the torque converter clutches of debris which causes the clutch pack to hang and cause shuddering.

The torque converter clutch in these gearboxes is not spring return assisted. It releases by centrifugal force once the supply circuit is exhausted (cut off) in the valve body.

In some cases the torque converter needs to be changed out to remedy this issue.

A bit of trans tune by seafoam helps in cleaning out the torque converter clutches of debris which causes the clutch pack to hang and cause shuddering.

The torque converter clutch in these gearboxes is not spring return assisted. It releases by centrifugal force once the supply circuit is exhausted (cut off) in the valve body.

In some cases the torque converter needs to be changed out to remedy this issue.