CVT valve body housing repair 722.8 Mercedes CVT A-class B-class

A common problem with the Mercedes CVT 722.8 is the appearance of a crack in the valve body. The crack always appears in the same place and this can be considered a design miscalculation of engineers, in this place the aluminum is too thin and aggressive operation of the box (especially in winter without preheating) leads to the destruction of the valve body.

As a result, we get pressure loss and such errors in computer diagnostics:

• 0868 The actual hydraulic pressure in the continuously variable transmission (CVT) is too low
• 2723 Impermissible opening of hydraulic brake “Reverse gear” has occurred in the CVT (this error does not always indicate a crack, it is worth checking the solenoids and plungers)
• 2732 Impermissible opening of hydraulic clutch “forward gear” has occurred in the CVT (this error does not always indicate a crack, it is worth checking the solenoids and plungers)

It would seem that a crack can simply be welded, but the use of argon-arc (TIG) welding does not solve the problem, the specific alloy of the valve body and the wall thickness do not allow to restore the tightness of the plate qualitatively and reliably.

The solution is laser welding, the technology has already been tested on more than a dozen valve bodies and has proven to be excellent, in the photo below you can see what a typical crack looks like and what a seam from a laser welding machine looks like.

In 722.8, the electronic conductor plate of the box often fails, we also repair it, you can find it at the link below:

• CVT conductor plate repair 722.8 Mercedes A-class B-class