Series 55 – Section 8.2 Battery Charging Alternator

Section 8.2
Battery Charging Alternator

The battery charging alternator provides a source of electrical current for maintaining the storage battery in a charged condition and supplies sufficient current to carry any other electrical load requirements up to the rated capacity of the alternator.‪

The battery charging circuit consists of an alternator, a voltage regulator, a battery(s) and the connecting wiring. See Figure "Typical Alternator Location" , for parts of the battery charging alternator.‪

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1.Charging Alternator‪

Figure 1. Typical Alternator Location

The 25-SI alternator typically used on the engine is a hinge-mounted, alternating current (AC), self-rectifying unit. See Figure "Mounting of Alternator" .‪

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1.Lower Alternator Support Bracket‪

6.Alternator Support Strap‪

2.Flat Washer (2)‪

7.Support Strap Bolt‪

3.Lock Washers (2)‪

8.Alternator Assembly‪


9.Lower Alternator Support Bolt‪

5.Water Pump Assembly‪

10.Upper Alternator Support Bolt‪

Figure 2. Mounting of Alternator

On engines equipped with the SI series Delco-Remy alternators, the voltage regulator is typically electronic and is located inside the alternator. Refer to the appropriate manufacturer's service instructions for complete regulator and alternator servicing information.‪

The alternator is front mounted and belt driven using the crankshaft drive pulley.‪

Section 8.2.1
Repair of Alternator

Refer to the OEM guidelines for alternator service procedures.‪

Section 8.2.2
Cleaning and Removal of Alternator

Precleaning is not necessary.‪

Remove the alternator as follows:‪


To avoid injury from accidental engine startup while servicing the engine, disconnect/disable the starting system.‪


To avoid injury from hot surfaces, allow engine to cool before removing any component. Wear protective gloves.‪

  1. Disconnect the cables at the batteries.
  2. Tag each lead to ensure correct connection when the alternator is reinstalled.
  3. If the alternator has more than the output cable lead, disconnect all other leads from the alternator, and tag each one to ensure correct installation.
  4. Remove the alternator output cable.
  5. Remove the top alternator mounting bolt to allow slack in the drive belts.
  6. Remove the drive belts.
  7. Loosen and remove the nut and washer at the rear alternator mounting flange.
  8. While supporting the alternator, remove the alternator-to-bracket bolt to prevent it from falling.
  9. Remove the alternator carefully to prevent damage.
  10. Remove and retain the alternator pulley locknut, alternator pulley, and fan from the unit.
Inspection of Alternator

Refer to OEM guidelines for alternator inspection procedures.‪

Section 8.2.3
Installation of Alternator

Install alternator as follows:‪

  1. Install alternator mounting bracket, if removed, to the block. Torque the mounting bolts to 49-68 N · m (36-50 lb · ft).
  2. Install the fan, drive pulley and locknut, if removed, to the alternator. Tighten the pulley retaining nut to 95-108 N · m (70-80 lb · ft) torque.
  3. If the pulley was not removed, check the retaining nut for proper torque. Torque the retaining nut to 95-108 N · m (70-80 lb · ft), as necessary.
  4. Position the alternator on the mounting bracket, and align the holes in the alternator mounting flanges with the tube in the bracket.
  5. Install the upper alternator-to-bracket bolt and locknut. Install the lower rod bolt, washer, nut on lower rod bolt installed, through the adjusting rod bracket. Tighten both bolts finger-tight.
  6. Install the drive belts in the grooves of the alternator and crankshaft drive pulleys.
  7. Adjust the alternator belt tension. Refer to "13.4.7 Drive Belts" .
  8. Tighten the alternator-to-mounting bracket bolt and nut and the alternator-to-adjusting rod bracket bolt to 81-95 N · m (60-70 lb · ft) torque.
  9. Attach the wires and cables to the alternator. Ensure that each one is correctly installed in the location from which it was removed. Keep all connections clean and tight.
Checking Alternator Belt Tensioning

The recommended tension for a new belt is 300 lb (1.33 kN). However, because a new belt loses tension rapidly during the first few minutes of operation, it is important to check the tension after running the engine for 10 to 15 minutes. To check belt tension, use the following procedure procedure:‪

  1. Tension the new drive belt to 300 lb (1.33 kN) using Kent-Moore belt tension gage J 41251 or equivalent.
  2. Start and run the engine from 10 to 15 minutes to allow the belt to warm up and seat in the pulley grooves.
  3. Stop the engine, and allow it to cool for 10 to 15 minutes.
  4. Measure belt tension:
    1. If tension is 200 lb (0.89 kN) or more, no further belt tension checking is required.
    2. If tension is less than 200 lb (0.89 kN), retension the belt to 200 lb (0.89 kN).

Series 55 Service Manual - 6SE55
Generated on 10-13-2008

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