LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Land Rover >> 1989 >> Range Rover Base >> Repair and Diagnosis >> Electrical >> Charging Systems >> Generators & Regulators >> Bench Testing >> Alternator
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Bench Testing: Alternator

  1. Remove the alternator. See ALTERNATOR  under REMOVAL & INSTALLATION.
  2. Disconnect the suppressor and remove the alternator cover.
  3. Disconnect the lead and remove the rectifier assembly.
  4. Note the arrangement of the brush box connections and remove the screws securing the regulator to the brush box and remove. This screw also keeps the inner brush plate in position.
  5. Remove the screw keeping the outer brush box in position and remove both brushes.
  6. Check brushes for wear by measuring length of brush protruding beyond the brush box molding. If length is 0.4" (10 mm) or less, install new brushes.
  7. Check that brushes move freely in holders. If brush is sticking, clean with a mineral spirit moistened cloth or polish sides of brush with fine file.
  8. Check brush spring pressure using push-type spring gauge. Gauge should register 5-10 ozs. (136-279 g) when brush is pulled back until face is flush with housing. If reading is outside these limits, install a new brush assembly.
  9. Remove the two screws securing the brush box to the slip ring end bracket and lift off the brush box assembly.
  10. Secure clamp alternator in a vice and release the stator winding cable ends from the rectifier by applying a hot soldering iron to the terminal tags of the rectifier. Pry out the cable ends when the solder melts.
  11. Remove the two remaining screws securing the rectifier assembly to the slip ring end bracket and lift off the rectifier assembly. Further disassembly of the rectifier is not required.
  12. Check the diodes. Connect the test equipment as shown and test each diode in turn, note weather lamp lights, then reverse test lead connections. See Fig 1 . The lamp should light in one direction only. Replace the rectifier assembly if a faulty diode is diagnosed.
    Fig 1: Testing Diodes
    G00097775Courtesy of LAND ROVER NORTH AMERICA, INC.
  13. Remove the slip ring end bracket bolts and lift off the bracket.
  14. Connect a 12 volt battery and a 36 watt test lamp to two of the stator connections. Repeat the test replacing one of the two stator connections with the third. See Fig 2 . If test lamp fails to light in either test, install a new stator.
  15. Using a 110 volt AC supply and a 15 watt test lamp, test for insulation between any one of the three stator connections and stator laminations. See Fig 3 . If test lamp lights, install a new stator.
    Fig 2: Testing Stator (1 Of 2)
    G00097776Courtesy of LAND ROVER NORTH AMERICA, INC.
    Fig 3: Testing Stator (2 Of 2)
    G00097777Courtesy of LAND ROVER NORTH AMERICA, INC.
  16. Clean surfaces of slip rings using a solvent moistened cloth.
  17. Inspect slip ring surfaces for signs of burning; remove burn marks using a very fine sandpaper. On no account should emery cloth or similar abrasives be used, or any attempt be made to machine the slip rings.
  18. Note the position of the stator output leads in relation to the alternator fittings, and lift the stator from the drive end bracket.
  19. Connect an ohmmeter to the slip rings. A reading of 2.6 ohms should be recorded. See Fig 4 .
  20. Using a 110 volt AC supply and a 15 watt test lamp, test for insulation between one of the slip rings and one of the rotor poles. If the test lamp lights, install a new rotor. See Fig 4 .
    Fig 4: Testing Rotor
    G00097778Courtesy of LAND ROVER NORTH AMERICA, INC.
  21. To separate the drive end bracket and rotor, remove the shaft nut, washers, Woodruff key and spacers from the shaft.
  22. Remove bearing retaining plate by removing the three screws. Using a press, drive the rotor shaft from the drive end bearing.
  23. If necessary, to remove the slip rings or the slip ring end bearing on the rotor shaft , unsolder the outer slip ring off the shaft, repeat the procedure for the inner slip ring connection. Using a suitable extraction tool, remove the slip ring bearing from the shaft.
  24. Reverse the previous steps, noting the following points.
    • Use Shell Alvania RA, or equivalent, to lubricate bearings.
    • When installing slip ring end bearing, ensure it is fitted with open side facing rotor.
    • Using Fry's H.T.3 solder, or equivalent, on slip ring field connections.
    • When installing rotor to drive end bracket, support inner track of bearing. Do not use drive end bracket to support bearing when fitting rotor.
    • Tighten through bolts evenly.
    • Place brushes into housings before installing brush molding.
    • Tighten shaft nut to specification. See TORQUE SPECIFICATIONS  .
    • Install regulator pack to brush molding.
  25. Reconnect the leads between the regulator, brush box and rectifier. See Fig 5 .
  26. Install the alternator.
    Fig 5: Connecting Sequence Of Generator Connections
    G00097781Courtesy of LAND ROVER NORTH AMERICA, INC.
scientia non olet · About LEMON Manuals