It's unfortunate that MBUSA never initiated a Recall Campaign when they found out that the radiators made by Valeo could cause such a catastrophic failure. If ever there was a case where a recall was called for, this was it. This defect has affected many C, CLK, and E-Class vehicles built before 10/03.

There is some good news though. In my experience, regardless of how bad the contamination is, only a small percentage of cars suffering this failure have needed to have the transmission and torque converter replaced. The DTB outlining this issue has been revised a few times, but as of now, here's how it reads.

If the glycol contamination is less than 100mg/liter no action is needed. In cases where the contamination is greater than 100mg/liter, the radiator should be replaced with the improved version, and the transmission should be flushed. Prior to flushing the transmission, the filter should be replaced. As per the DTB, fourteen liters of ATF are needed. If the problem persists after the flushing procedure has been performed, the torque converter should be replaced. That’s how the DTB reads.

Now the bad news. Fourteen liters won’t get the job done in most cases. There’s almost always a huge improvement in shift quality following the flush, but there’s usually still some jerking/bucking that makes the car pretty much a PIA to drive. FWIW, transmission function continues to improve the more the car is driven. At my dealership, I'll ask the SA to obtain the clients' permission for myself, or one of the other Shop Foreman to take the car home overnight, to rack up as many miles as possible. Like I said, the more the car is driven, the better it gets. In many cases, this is all it takes to restore normal transmission function, but in some cases, to make the problem go away completely, we’ll need to drop the pan at least one more time, remove the filter, and let as much fluid drain out as possible. We'll then re-install the same filter, fill the transmission, and continue driving the car. In the last few years, we've taken this approach several dozen times with good success. We've only had to replace two transmissions/converters.

Lastly, all MB dealers were sent a glycol test-kit a few years ago. It works very well, but in nearly every case, performing this test isn't necessary. The contamination is usually so obvious no test is needed.