Poor starting

My son has a 55-plate Ford Mondeo 2.0 diesel that is becoming increasingly difficult to start and runs roughly, especially at tickover. From what I have read, the dual mass flywheel could be to blame as this is where the timing is picked up. Is this likely or should we look somewhere else before we go to the expense of changing the DMF? Graham Wharton Although the crankshaft position sensor does take its data from the DMF, it comes from the solid mass of the flywheel and not any area that might become variable from wear.

The first thing I would check is the glow plug system. The glow plugs can be found at the front of the engine, just below the fuel rail. By removing the electrical connectors and using an ohmmeter between the glow plug terminal and earth, the condition of the glow plugs can be checked. The ohmmeter should read below 6Ω; a high resistance or open circuit will indicate a failed glow plug, which will need changing. Using a test light I would also ensure that the glow plugs are being fed when the ignition is first turned on and the dash warning light is illuminating.

You do not mention the mileage the vehicle has covered, but I would also check the injector leak-off pipes for any signs of weeping. These are one of the common failure points on the 2.0 diesel engine, and signs of weeping indicate that air is being drawn into the system, which will result in poor starting.

If the running problems are not confined to cold starting and running there are many other components which may be at fault. The most common of these include the cylinderhead temperature sensor, coolant temperature sensor, failing injectors and the EGR valve.