![does sprinter effect stack does sprinter effect stack](https://i.stack.imgur.com/EKEyN.gif)
A quick and dirty test to indicate any problems with the variable vanes is to remove the air box or air filter housing and listen as the engine is revved. Look for any misalignment of the lever throughout its stroke as it passes through the turbo body, as the bearing surfaces on this shaft can wear or oval allowing the internal lever to ride over the annular ring inside resultantly not moving any of the vanes. Inspect the external lever that the actuator push rod attaches to, ensure this moves smoothly as you accelerate / rev the engine. A single action of pushing or pulling the actuator rod moves all the vanes inside the turbo in unison, developing more or less turbo charge dependant on its position. This lever engages in an annular ring that in turn interlaces with a set of similar levers attached to each variable vane. The charge actuator resides bolted to the turbo body on an extended bracket, its push rod connects to a small lever that enters into the turbo body casting, moving a small lever shaped rather like a dog-bone.
![does sprinter effect stack does sprinter effect stack](https://i.stack.imgur.com/xfEge.png)
![does sprinter effect stack does sprinter effect stack](https://i.stack.imgur.com/7QjQI.png)
The turbo itself is a Garrett VNT variable vane turbo, the details of which you will find elsewhere on this site. ( ) It is controlled by a vacuum actuator that moves a set of mechanical vanes within the turbo to vary the turbo charge rate – there is no conventional dump valve on these turbos and many times you will wrongly read people refer to it as the ‘dump valve actuator’.