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16. Figure 40–5 A typical starter motor. Continued

22. Figure 40–7 The interaction of the magnetic fields of the armature loops and field coils creates a stronger magnetic field on the right side of the conductor, causing the armature loop to move toward the left. Continued

34. Figure 40–18 A cutaway of a typical starter motor.

37. In the past, it was common to see service technicians hitting a starter in their effort to diagnose a no-crank condition. Often the shock of the blow to the starter aligned or moved the brushes, armature, and bushings. Many times, the starter functioned after being hit—even if only for a short time. However, most of today’s starters use permanent - magnet fields, and the magnets can be easily broken if hit. A magnet that is broken becomes two weaker magnets. Some early PM starters used magnets that were glued or bonded to the field housing. If struck with a heavy tool, the magnets could be broken, with parts of the magnet falling onto the armature and into the bearing pockets, making the starter impossible to repair or rebuild. Don’t Hit That Starter!

39. Figure 40–20 Many gear-reduction starters use a planetary gear-reduction assembly similar to that used in an automatic transmission.

60. Figure 40–27 Voltmeter hookups for voltage-drop testing of a GM-type cranking circuit. Continued

61. Figure 40–28 Voltmeter hookups for voltage-drop testing of a Ford-type cranking circuit. Continued

62. Figure 40–29 To test the voltage drop of the battery cable connection, place one voltmeter lead on the battery terminal and the other voltmeter lead on the cable end and crank the engine. The voltmeter will read the difference in voltage between the two leads which should not exceed 0.2 volt (200 mV). NOTE: Before a difference in voltage (voltage drop) can be measured between the ends of a battery cable, current must be flowing through the cable. Resistance is not effective unless current is flowin g. If the engine is not being cranked, current is not flowing through the battery cables and the voltage drop cannot be measured.

67. Figure 40–30 GM solenoid ohmmeter check. The reading between 1 and 3 (S terminal and ground) should be 0.4 to 0.6 ohm (hold-in winding). The reading between 1 and 2 (S terminal and M terminal) should be 0.2 to 0.4 ohm (pull-in winding). If a starter is inoperative, check for voltage at the S ( start ) terminal of the starter solenoid. Some newer models with antitheft controls use a relay to open this control circuit to prevent starter operation. See Figure 40–31 for a starter system diagnostic chart. Continued

68. Figure 40–31 Starter trouble diagnostic chart. See the chart on Page 429 of your textbook.

74. Figure 40–33 Before disassembly of any starter, mark the location of the through bolts on the field housing. This makes reassembly easier. Continued

75. Figure 40–34 Removing the solenoid from the starter on a GM-type starter assembly. Continued

76. Figure 40–35 Rotate the solenoid to remove it from the starter housing. ( Caution: The plunger return spring exerts a force on the solenoid and may cause injury if not carefully released. Continued

77. Figure 40–36 The brushes should be replaced if worn to less than 50% of their original length. Replace if less than 1/2-inch long (13 millimeters). Continued

78. Figure 40–37 An exploded view of a General Motors starter. Continued

79. Figure 40–38 To replace the starter drive unit, the retainer and clip must be removed from the armature shaft. A box-end wrench and a hammer can pop the retainer off of the spring clip.

83. Figure 40–40 Replacement starter brushes should be installed so the beveled edge matches the rotation of the commutator. Continued

89. Continued Many GM starters use shims (thin metal strips) between the flywheel and the engine block mounting pad to provide the proper clearance. NOTE: Be sure that the locking nuts for the studs are tight. Often the retaining nut that holds the wire to the stud will be properly tightened, but if the stud itself is loose, cranking problems can occur. NOTE: Some manufacturers use shims under starter drive-end housings during production. Other manufacturers grind the mounting pads at the factory for proper starter pinion gear clearance. If any GM starter is replaced, the starter pinion must be checked and corrected as necessary to prevent starter damage and excessive noise.

91. CAUTION: Be sure to install all factory heat shields to help ensure proper starter operation under all weather and driving conditions. NOTE: The major cause of broken drive-end housings on starters is too small a clearance. If the clearance cannot be measured, it is better to put a shim between the engine block and the starter than to leave one out and risk breaking a drive-end housing.

93. Connect a starting-charging-testing unit to a vehicle. Instead of connecting the ampere probe around the positive cable, connect it around the ground cable (all cables should be within the ampere probe if more than one ground cable is connected to the battery terminal). All ammeter readings should be the same if taken on the positive or negative cables of the battery. Ground Wire Current Flow - Part 2 NOTE: Most starting-charging-testing units use an arrow on the ammeter probe to show polarity. Reversing the direction in which the arrow points is often necessary to read the correct polarity (positive or negative) on the tester display.

94. Most General Motors starter motors use a pad mount and attach to the engine with bolts through the drive-end (nose) housing. Many times when a starter is replaced on a GM vehicle, the starter makes noise because of improper starter pinion-to-engine flywheel ring gear clearance. Instead of spending a lot of time shimming the new starter, simply remove the drive-end housing from the original starter and install it on the replacement starter. Because the original starter did not produce excessive gear engagement noise, the replacement starter should also be okay. Reuse any shims that were used with the original starter. This method is better than having to remove and reinstall the replacement starter several times until the proper clearance is determined. Reuse Drive-End Housings to Be Sure

95. STARTING SYSTEM TROUBLESHOOTING GUIDE See the chart on Page 432 of your textbook.

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