Because of its unique design, the diesel engine does not utilize spark plugs, rotor or distributor. In fact, the diesel engine uses no sparking method at all. For this reason, the proper functioning of the diesel engine is not dependent upon timing and spark delivery, like a gas engine, instead the diesel engine relays on the injection pump to deliver the correct amount of fuel at the desired time. For this reason, diesel timing is more correctly referred to as injection timing.
With the diesel engine's unique characteristics, comes the requirement that different tools and equipment are needed to perform many of the service procedures. This is the case with injection timing. In this situation, no timing light is used, instead a dial indicator is used. Some of the tools necessary to service a diesel vehicle are available at local parts stores or through rental businesses, but before tackling any diesel procedure, make sure the tools are available.