Mercedes-Benz W211 fuel injector leak
How can you tell that a W211 CDI has a leaking injector?
Symptoms are a fuel smell inside the car, gurgling at the base of the injector and uneven running. Leak-back affects starting most, and at worst the car goes into limp mode at full throttle. Fuel consumption may also rise.
How is an injector leak on a W211 CDI fixed?
Often replacing the injector's base seal is enough, once the seal has flowed out of shape. Other seals do not need to be replaced unless they leak. The injector is pulled straight up, because sideways force easily breaks it.
What is the injector tightening procedure on a W211 CDI?
According to the instructions the tightening is 7 Nm followed by 90 degrees. A newer procedure adds a second 90-degree turn, and on the OM646 7 Nm + 2 x 90 degrees was used. Check the tightness after about 500 km of driving.
When should the injectors of a W211 CDI be tested?
Test on the basis of symptoms, not mileage. The test looks at leak-back cold and warm and at the correction values, that is, the injector's deviation from normal. When the injectors are within tolerance, the sum of the correction values is zero. An injector leaking at the wrong time can damage the piston.