The cranking system has the the following parts (refer to Figure 8-7):
• Connection to battery power
• The ignition switch and wiring
• A cranking motor assembly, with these parts:
– A solenoid/switch
– A motor
– A gear reduction assembly
– A drive mechanism
Operation of the cranking system is similar to that of gasoline-powered engines, using a 12-volt circuit.
The cranking motor is specific to diesel engine use and provides a high amount of torque through the use of gear reduction (refer to Figure 8-6). Two versions of the cranking motor are used, depending on 2WD or 4WD applications.
The cranking motor mounts to the cylinder case, using two bolts with washers (see Figure 8-8, view A). A bracket adds to the cylinder case support of the cranking motor, and a heat shield protects related wiring (see Figure 8-8, view B).
As a part of service, the cranking motor may have shims installed to obtain a clearance of 0.5 to 1.5 mm (0.020 to 0.060 in.) between the pinion and flexplate gear teeth (see Figure 8-9). A special procedure is used to make the clearance measurement as part of noise diagnosis (see page 8-41). Shims of two thicknesses (1.0 [0.039 in.] and 2.0 mm [0.079 in.]) may be used to obtain clearance, with a total shim pack thickness limit of 4.0 mm (0.158 in.).
During bench testing, the cranking motor has a no-load test specification of using 130 to 190 amperes at 10 volts, with a pinion speed of 2300 to 5600 rpm.
