Alternator Replacement – 2.5L NA

Overview

This guide outlines the procedure to replace the alternator on all Porsche 944 variants with an 8-valve engine, covering both pre-1985.5 (83–85.5) and 1985.5 onwards (86–88) variants. The alternator is critical for charging the battery and powering electrical systems. This process involves removing several components to access the alternator, making it time-consuming but manageable for DIY enthusiasts with mechanical experience. For pre-1985.5 models, ensure you address the specific air cooling duct if equipped. Always verify torque settings and part compatibility before starting.

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Tools Required

• Metric socket set (including 10mm (3/8 inch) socket)
• Metric wrench set (including 13mm (1/2 inch) wrench)
• Screwdriver set (flathead, including stubby and long thin-blade)
• Jack stands and floor jack or ramps
• Catch pan
• Pry bar

Parts Required

• Alternator (new or rebuilt, 944 603 111 00 for pre-85.5, 944 603 112 00 for 85.5 onwards)
• Alternator/AC compressor belt (944 102 219 03), if replacement is needed

Step-by-Step Procedure

Step 1: Prepare the Vehicle

1. Disconnect the battery by removing both the positive and negative terminals, starting with the positive terminal to prevent electrical shorts.
2. Raise the vehicle using a floor jack and secure it on jack stands, or drive it onto ramps for access to the underside. Jack stands provide more working space.
3. Remove the skid pan (undertray) from beneath the engine compartment using a 10mm (3/8 inch) socket to remove the M6 bolts.

Step 2: Remove the Alternator/AC Compressor Belt

4. Locate the AC compressor turnbuckle tensioner, which adjusts the alternator/AC compressor belt tension.

For Pre-85.5 models:

• Loosen the lock nuts on both ends of the turnbuckle tensioner using a 13mm (1/2 inch) wrench. Rotate the turnbuckle to relieve tension on the belt. Remove the turnbuckle retaining bolt on the alternator and rotate the alternator toward the engine to remove the belt.

For 85.5 Onwards models:

• Loosen the turnbuckle retaining bolt on the compressor a few turns using a 13mm (1/2 inch) wrench. Use a pry bar between the compressor and engine block to relieve 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 minimizes re-tensioning adjustments during reinstallation.

5. If the vehicle has power steering, note that the alternator/AC compressor belt cannot be fully removed without removing the power steering belt. Follow this link to ensure this step – Power Steering Belt Removal – is followed accurately, if full removal is needed.

Step 3: Disconnect Cooling Duct (if equipped)

6. For Pre-85.5 models:

   • If equipped, locate the flexible air cooling duct running from the left front fender well to the black plastic shroud on the back of the alternator. Disconnect the duct using a stubby flathead screwdriver or a long thin-blade flathead screwdriver, depending on clamp orientation. This duct supplies critical cooling air and must be reinstalled.

7. For 85.5 Onwards models:

   • Check for the air cooling duct. If present, disconnect it as described above. Note that this duct is less common in later models but still possible.

Step 4: Remove Air Intake Components

8. Remove the air box and air flow meter from the vehicle to access the alternator. Use a flathead screwdriver to loosen any hose clamps and carefully disconnect electrical connectors.

Step 5: Remove Alternator Retaining Bolts

9. Locate and remove the lower alternator retaining bolt at the back of the compressor using a 13mm (1/2 inch) socket or wrench.
10. Remove the remaining alternator retaining bolts, typically two additional bolts, using a 13mm (1/2 inch) socket or wrench. Do not fully tighten these during reinstallation until the belt is installed.

Step 6: Disconnect and Remove Alternator

11. If equipped, lift the alternator slightly to remove the black plastic cover on the back, exposing the wiring connections.
12. Disconnect the electrical wires from the back of the alternator, noting their positions for reinstallation.
13. Remove the alternator from the vehicle, maneuvering it carefully to avoid damaging surrounding components.

Step 7: Install New Alternator

14. Position the new alternator (944 603 111 00 for pre-85.5, 944 603 112 00 for 85.5 onwards) in the vehicle, ensuring the rear plastic cover is in place if equipped.
15. Reconnect the electrical wires to the alternator, securing them firmly in their original positions.
16. Install the alternator retaining bolts but do not fully tighten them yet.

Step 8: Reinstall Alternator/AC Compressor Belt

17. Install the alternator/AC compressor belt (944 102 219 03) by reversing the removal process.

For Pre-85.5 models:

• Rotate the alternator toward the engine, install the belt, and reattach the turnbuckle retaining bolt. Tighten the turnbuckle to tension the belt, then secure the lock nuts.

For 85.5 Onwards models:

• Rotate the compressor toward the engine, install the belt, and reattach the turnbuckle retaining bolt. Use the pry bar to tension the belt, then tighten the bolt.

18. Install the bottom nut for the rear alternator cover, if equipped, using a 10mm (3/8 inch) wrench.
19. Tighten the AC compressor turnbuckle to properly tension the belt. Tighten the alternator retaining bolts to 20 Nm (15 ft-lbs).

Step 9: Reinstall Cooling Duct and Air Intake

20. Reinstall the air cooling duct to the alternator shroud, if equipped, securing it with the clamp using a flathead screwdriver.
21. Reinstall the air flow meter and air box, ensuring all hose clamps and electrical connectors are secure.

Step 10: Final Reassembly and Checks

22. Reinstall the skid pan under the engine compartment, securing the M6 bolts with a 10mm (3/8 inch) socket to 8 Nm (6 ft-lbs).
23. Reconnect the battery, starting with the negative terminal, then the positive terminal.

Post Procedure Checklist

• Start the vehicle and verify the alternator is charging (battery warning light should be off, and voltage should read 13.5–14.5V).
• Check the alternator/AC compressor belt tension and ensure it deflects about 5mm (0.2 inches) under moderate thumb pressure.
• Inspect for any loose bolts or disconnected hoses, particularly the air cooling duct if equipped.
• Ensure no tools or debris are left in the engine compartment.

Sources

• Clark’s Garage
• Pelican Parts
• Porsche 944 Workshop Manuals
• Youtube