Alternator Replacement

Introduction

Replacing the alternator in a 944 is not extremely difficult, though it is somewhat time-consuming because a number of parts must be removed to reach it.

New alternators carry a significant cost. Bosch alternators are commonly rebuilt by specialty shops, which can be a worthwhile option. If the car cannot be taken off the road long enough for a rebuild, a new or rebuilt exchange unit is the alternative. If no core deposit is required, consider having the old alternator rebuilt as a spare regardless — it may also be possible to sell a rebuilt unit to recoup some expense.

Tools

• Metric socket set
• Metric wrenches
• Screwdriver set
• Jack stands and floor jack, or ramps
• Catch pan
• Pry bar

Other Procedures Needed

• COOL-02 — Coolant System Draining, Filling, and Venting (Turbocharged Cars)

Removal

1. Disconnect the battery. Disconnect both terminals if possible; disconnecting the positive lead is the minimum requirement.

2. Place the car on jack stands or ramps. Jack stands provide more working room.

3. Remove the skid pan from under the engine compartment (M6 bolts — 10 mm socket).

4. Remove the alternator/AC compressor belt using one of the following methods:

   a. Standard method: Loosen the lock nuts on either end of the AC compressor turnbuckle tensioner and rotate the turnbuckle until belt tension is relieved. Remove the turnbuckle retaining bolt on the alternator, rotate the alternator toward the engine, and slide the belt off.

   b. Alternate method: Loosen the turnbuckle retaining bolt on the compressor a few turns, then use a pry bar between the compressor and the block to relieve belt tension. While holding the pry bar, remove the turnbuckle retaining bolt on the compressor, rotate the compressor toward the engine, and remove the belt. This method preserves the original belt tension so reinstallation requires little or no adjustment.

   c. On cars equipped with power steering, the alternator/AC compressor belt cannot be fully removed without first removing the power steering belt — though it need not be fully removed unless replacement is required.

5. Loosen and remove the lower alternator retaining bolt at the back of the compressor.

Note: Some 944s have an air cooling supply via a flexible duct running from the left front fender well to a black plastic shroud on the back of the alternator. This must be disconnected before the alternator can be removed.

6. If equipped, remove the flexible cooling hose that runs from the front left fender to the black plastic shroud on the back of the alternator. A stubby flat-tip screwdriver works well here, or a long thin-blade screwdriver if the clamp is oriented favorably. This hose must be reinstalled — it supplies cooling air to the alternator.

7. Remove the air box and air flow meter from the vehicle.

8. On turbocharged cars, perform the following:

   a. Remove the intercooler outlet pipe to the intake manifold. Also remove the rubber inlet plenum boot (to the turbocharger). b. Drain as much coolant as possible from the coolant expansion tank using a hand vacuum pump or siphon pump. c. Disconnect the coolant hose from the coolant expansion tank to the crossover pipe and to the turbocharger cooling pump. Have rags ready to catch residual coolant in the hoses.

9. Remove the remaining alternator retaining bolts.

10. If equipped, lift the alternator sufficiently to remove the black plastic cover from the back of the alternator.

11. Disconnect the wires from the back of the alternator and remove the alternator from the vehicle.

Installation

1. Place the new alternator into the vehicle. Ensure the rear alternator cover is in position before installing.

2. Connect the wires to the alternator and attach the cover to the back.

3. Install the alternator retaining bolts — do not tighten yet.

4. Install the alternator belt.

5. If not already done, install the bottom nut for the rear alternator cover.

6. Install the AC compressor turnbuckle to tension the AC compressor/alternator belt.

7. Tighten the alternator retaining bolts.

8. Install the cooling duct for the alternator.

9. For turbocharged cars:

   a. Install the coolant hose from the coolant reservoir to the crossover pipe and turbo cooling pump. b. Install the rubber inlet plenum boot on the turbocharger suction. c. Install the intercooler discharge pipe to the intake manifold.

10. Install the air flow meter and air box.

11. On turbocharged cars, fill and vent the coolant system per COOL-02.

12. Install the skid pan.