Mercedes-Benz W124 diesel bleeding and starting problems
How do you bleed the Mercedes-Benz W124 diesel fuel system after a filter change?
1. Fill the new filter with diesel and crank the engine; the air usually clears after a few attempts. 2. If the engine will not start, loosen the pressure line to the injectors slightly at the engine end. 3. Tighten the line when the engine is running. The throttle position does not matter, and pumping is of no use.
Why does a Mercedes-Benz W124 diesel start badly and smoke white when cold?
The cause is often an air leak in the fuel system. The O-rings of the injection pump delivery valves can leak air, and replacing them removes the symptom. Also check that the fuel hoses are intact and secure; a wet hose reveals the leak point.
Why does a Mercedes-Benz W124 diesel not get fuel or stall while driving?
Both valves of the lift pump can be faulty, or the tank vent does not work, creating a vacuum in the tank; when opening the cap there should normally be a hiss. The operation of the pump can be checked by disconnecting the hose going up from the pump and starting the engine: fuel should splash out. Replace the lift pump O-rings at the same time.
What should be noted when changing the fuel filter?
Use the filter for the diesel model: the petrol model's filter is too fine and blocks the flow. The inlet and return hoses must be connected the right way round, otherwise the car jerks and stalls at full throttle. Fill the filter with diesel before installing it.