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How to replace an alternator?

The alternator can most easily be accomplished with the engine out of the car, but it can also be done with the engine in the car by following the steps below.

How to replace an alternator?
How to replace an alternator?

Raising the fan housing

  1. Remove the drive belt as follows
    1. The front half of the alternator pulley has two cut-out slots in it. Inserting a thin screwdriver in either slot locks the pulley so you can loosen/tighten the 19mm retaining nut. Remove the retaining nut on the alternator shaft with the 19mm wrench, then slip off the washer, any spare shims, and the outer pulley half. Take note of how many shims are between the pulley halves so you can easily re-tension the pulley on reassembly.
    2. Slip the belt off the crankshaft pulley and remove it.
    3. Remove the inner pulley half, being careful to remove the Woodruff key and stow it and the shims and nut in a baggie in a safe place.
  2. Remove the air cleaner.
  3. Detach the accelerator cable from the throttle lever and remove the fuel line from the fuel pump to the carburetor.
  4. Remove the carburetor.
  5. Pull out the accelerator cable guide tube and pull the accelerator cable forward, out of the fan housing.
  6. Remove the cable from the negative terminal of the battery.
  7. Label and then detach the electrical connectors from the alternator.
  8. Remove the strap that holds the alternator to the support.
  9. Disconnect the ignition cable from the coil and the fresh air tubes on either side of the fan housing. Disconnect the spark plug wires from the attachments in the fan housing (three places).
  10. Remove the hood and the hood hinge brackets. You must remove the brackets to get enough clearance to lift the fan shroud.
  11. On the left side of the Beetle, reach down in front (front) of the fan housing with a 10mm box-end wrench (ring spanner) and remove the bolt for the oil cooler cover and the bolt that holds the fan housing to the oil cooler flange. This is awkward and you’ll be working largely by feel.
  12. Remove the oil cooler cover and the air duct.
  13. Unbolt the thermostat and unscrew the thermostat from its rod.
  14. Disconnect and remove the connecting link between the cooling flaps in front of the fan housing (don’t lose the spring).
  15. Remove the two bolts on either side of the fan housing. The one on the left also supports the metal fuel line, and you may need to disconnect this line from the fuel pump to move it out of the way.
  16. Raise the fan housing enough so you can remove the four mounting bolts from the outer fan cover on the rear of the shroud. This will allow the alternator/fan assembly to be removed — the fan housing can be removed completely at this point if desired. If the fan housing is simply raised, it helps to support it on either side with wooden blocks. (Its really easier to just pull the fan housing out of the Beetle.)
Remove the fan housing
Remove the fan housing

How to remove the alternator

  1. Make sure that the cable from the negative terminal of the battery is removed.
  2. Make index marks on the outer fan cover and on the fan housing (top and side for example) to ensure proper alignment during reassembly.
  3. With the fan housing raised, remove the four bolts that hold the fan cover (with the alternator attached) to the fan housing.
  4. Pull the the alternator away from the fan housing.
  5. Reinstall the pulley and the mounting nut on the alternator shaft.
  6. Drill a shallow hole in a large wooden block to accomodate the fan pulley nut on the rear of the alternator shaft. Position the alternator/fan assembly vertically on the wooden block, with the nut in the hole you drilled and the fan pulley resting on the block. Put the 1-7/16″ socket on the impact driver and then use the driver to removed the fan nut on the other end of the shaft.
  7. Remove the shims, washer and hub, noting the position of the shims and washers for reassembly. (You may need to use a puller to get the hub off of the shaft.)
  8. Remove the fan, then remove the two 10-mm nuts that are now exposed and remove inner fan cover, reinforcement flange, and outer fan cover.
Remove the alternator
Remove the alternator

How to reassemble the alternator

  1. Install the fan pulley on the end of the alternator shaft. Make sure the hub is seated properly on the Woodruff key.
  2. Replace the hub on the fan end of the shaft, making sure the hub is seated properly on the Woodruff key. Replace the washer and shims in the same configuration they were in originally.
  3. Replace the outer fan cover, the reinforcement flange, and the inner fan cover. Replace the two 10-mm nuts that hold the assembly to the alternator and tightened them securely.
  4. Place a 19mm wrench on the fan pulley nut to hold the alternator shaft in place, then tighten the 36mm fan-to-alternator shaft nut to 40 ft-lbs using the 1-7/16″ socket.
  5. Using a feeler gauge, measure the distance between the fan and fan cover. The recommended clearance is 0.08 inch (2.0 mm). If the clearance is incorrect, adjust it by varying the number of shims under the thrust washer. Store unused shims between the thrust washer and nut.
  6. Turn the fan by hand to check for binding.
  7. Install the alternator fan assembly into the fan housing. Make sure the four bolts that hold the outer fan cover to the housing are securely tightened.
  8. Reinstall the alternator pedestal, making sure to place gaskets on either side of the internal baffle. Tighten the four nuts securely with a 13mm wrench.
  9. Reinstall the fan housing in the car. Make sure the thermostat connecting rod is positioned correctly and does not bind. Be sure to properly adjust the thermostat (see Thermostat Installation procedure).
  10. Reconnect the cooling vane connector rod to the left cooling vanes.
  11. Reinstall the oil cooler vent tube and oil cooler tin. Make sure to use hex-head bolts to facilitate installation.
  12. Reinstall and the drive belt in accordance with the Drive Belt Check, Adjustment and Replacement procedure.
  13. Reinstall the carburetor and accelerator cable. Reattach the fuel line from the fuel pump.
  14. Check closely for interference between the accelerator pump linkage and the body of the alternator. It may be necessary to place a spacer under the carburetor to raise it a bit and/or flop the accelerator pump linkage around so that it doesn’t rub on the alternator.

How to wire the alternatior

How to wire an alternator
How to wire an alternator?

If you are replacing an alternator which uses an external voltage regulator (mounted under the rear seat) with an alternator having an internal voltage regulator, do the following:

  1. Remove the small blue wire and the small green wire from the regulator (terminals (61) and (DF) respectively).
  2. Cut off the push-on connectors from these wires and connect them together using a “butt” connector.
  3. Connect the small green wire to the (D+) terminal on the alternator.
  4. Remove the two large red wires from the (B+) terminal of the regulator. Cut off the push on connectors from these wires and splice them together with the red wire that WAS on the D+ terminal on the old generator using a “butt” connector. These two wires carry up to 50 amps to the battery, so the new connector MUST be big enough to handle that current.
  5. Connect the red wire that was on the D+ teminal of the generator to the B+ terminal on the new alternator.
  6. Reconnect the large red wire or a new 10-gauge red wire from the (B+) terminal on the alternator to the “30” terminal on the starter solenoid.
  7. Reconnect the cable to the negative terminal on the battery.
  8. The (D+) terminal on the alternator must be connected to a working “Alt” light in the instrument cluster.
  9. Check to make sure this bulb is working by turning on the ignition key (do not activate the starter motor!) If the “Alt” light in the instrument cluster comes on, the bulb is working and the alternator is grounded.
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