Mercedes-Benz W210 CDI injector leak and seal replacement
W210 CDI: how can I tell that an injector is leaking?
Typical symptoms are poor starting and an uneven engine sound. If rail pressure does not rise, one injector may be leaking straight into the return line. A long-term leak into the cylinder can make a hole in the piston, so the injectors should be tested in time.
How is excessive injector return leakage confirmed?
Transparent hoses are fitted in place of the return line connectors, and the flow is observed. The injector can also be removed and tested on a test bench. Often it is enough to replace the faulty injector with a good one; the whole injector set does not need to be renewed.
W210 CDI: diesel is leaking at the front of the engine - is the injector the cause?
The leak often comes from the O-ring of the plastic connector of the return line. If the hose has hardened or crumbles, replacing just the O-ring is not enough, and the pipe with its connectors should be renewed. A soft and flexible hose may be enough temporarily. The leak can also come from the joint of the injector body.
What should I watch out for when replacing the injector base seal?
An injector that has leaked for a long time can be stuck tight, and it should not be forced out. A broken glow plug should be replaced at the same time, because carbon deposits make removal harder. The threads are cleaned carefully so that the head does not crack, and a worn sealing surface may have to be levelled.