722.6 transmission

[tom941]

Hi;
I'm new to the forum and have a trans problem with my CLK320. The car suddenly acted as if the car was in neutral . shut off and restarted after sitting a few minutes and shifted again and then acted up again. got it home and checked codes- codes for slippage.The fluid looked burnt so I removed the trans and looked thru it. No sign of worn or damaged clutches but the center shaft rings were flat, so I resealed all of the clutch and brakes with new o rings . Reinstalled the trans and it worked fine for a couple of weeks,then the same symptoms.I tried a used valve body out of a junkyard with no change other then a bad conductor plate type fault.I cleared faults and tested again- trans would work and go into neutral with no codes. I then tried unplugging the trans control module and the symptoms remained the same- first time I started the car it moved normally, next time no go. also there is no apparent flow from the hose going to the trans cooler in the radiator. Does this sound like a bad torque converter?

[97 SL320]

Test cooler flow with the trans in gear, ( block wheels, have someone in the car on the brakes ) some trans don't have flow in park, not sure about the 722.6

A bad TC will just give poor acceleration ( slipping stator sprag ) or drag the motor down at higher speeds ( locket stator sprag ) .

What were the specific slippage codes?

You need to put a line pressure gauge on the trans and look at pressure prior / during the fault.

[MAVA]

Like Mr97 said,

You need to check line pressure gauge. The name of the game is pressure.. I'm assuming this is a pre-1999 CLK320?

No flow? Okay, I do not know the cooler line set-up on a CLK. I'm assuming it has the little V6 and not the 6-Inline. On the V6 E320, the top cooler line on the radiator is the line from the transmission with hot fluid(to the cooler to get cooled). If you disconnect the top line, and attach some clear vinyl tubing to a clear clean/new painters graduated 1 Gallon paint bucket. It should take about 20 to 30 seconds to empty out two-quarts of fluid with the engine idling in park. If it takes minutes, you have a pressure problem...

Once you are done, just pour the fluid back into the car, and do only two quarts.

In your case, the pressure regulating valve/spring can be shot or broken(common), and or the pressure regulating solenoid is just getting tired, and these old first generation 722.6 transmissions are having this problem. The solenoid will not generate any kind of code unless they open(electrically), or short out, but when they loose mechanical or magnetic properties you get no codes.

The slippage codes, or adaptation codes are critical for clutch wear. If you have the first generation 722.6, these are vulnerable to K2 bearing failure. If you find large chunks of copper washers, you are doomed, and it will follow with needle bearings parts, but even with loosing needle bearing parts the gears will hold..

Here are two threads with juicy info. The first one has some good info. The second has lots of data.Read them both well, and download the attachments from the other, and read those.

E420 Transmission Control Problems

No Transmission Fluid Symptoms - Benzworld.org - Mercedes-Benz Discussion Forum

Best of luck,

Martin