Sump Compression

Massey Ferguson – diesel in engine sump

Diesel mixing with oil in the engines sump has three possible causes :

The fuel lift pump has a perforated diaphram.
Diesel injector pump front seal leaking.
Heater plug valve is stuck in the open position.

The fuel lift pump diaphram is the most common culprit is the which perishes with age. Replace pump, engine oil & oil filter. Monitor oil level. To determine if this is in fact the cause remove fuel lift pump and inspect diaphram. The pump can also be connected remotely and hand operated to see if diesel leaks out of the rear where it bolts onto the engine block.

The heater plug located on the engines intake manifold ignites diesel  to preheat the motor before cold starting. It has a valve which opens to allow diesel through to be combusted by the electric element. If the valve is faulty diesel continually flows into the intake manifold causing poor running & in some cases locks up the engine when diesel lies on top of the pistons.

The injector pump shaft has an oil seal where the pump bolts onto its timing gear. If this seal is leaking it is a symtom of exessive pressure build up & the pump should be inspected by a diesel injection specialist.