Alternator Replacement

Overview

This guide walks you through replacing the alternator on your Porsche 944 with the 16v engine. The alternator keeps your battery charged and powers electrical systems, so replacing a faulty one is key to keeping your car running smoothly. While not overly complex, this job takes time because you’ll need to remove several parts to access the alternator. With some mechanical know-how, you can tackle this DIY project and save on labor costs.

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Tools Required

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

Parts Required

• New or rebuilt alternator –944 603 111 00
• Alternator belt (if replacing) – 944 102 219 03

Step-by-Step Procedure

Step 1: Prepare the Vehicle

1. Disconnect the battery by removing both terminals—start with the positive lead to stay safe.
2. Lift the car onto jack stands or ramps. Jack stands give you more room to work underneath.
3. Remove the skid pan under the engine using a 10mm (3/8 inch) socket to take out the M6 bolts.

Step 2: Remove the Alternator Belt

4. Locate the AC compressor turnbuckle tensioner. Loosen the lock nuts on both ends with a 13mm wrench.
5. Rotate the turnbuckle counterclockwise with a wrench until the alternator belt loosens.
6. Remove the turnbuckle retaining bolt on the alternator (13mm wrench), then pivot the alternator toward the engine to slip the belt off.
7. (Alternative method) Loosen the turnbuckle retaining bolt on the compressor a few turns. Use a pry bar between the compressor and engine block to ease tension, hold it there, remove the compressor’s turnbuckle bolt, pivot the compressor toward the engine, and take the belt off. This method keeps the tension setting for reinstallation.

Step 3: Disconnect Cooling Duct (If Equipped)

8. Check if your 944 has a cooling duct—a flexible hose from the left front fender well to a black plastic shroud on the alternator’s back.
9. If present, loosen the clamp with a stubby flat-tip screwdriver (or a long thin blade if aligned right) and detach the hose.

Step 4: Remove Air Box and Alternator Bolts

10. Take off the air box and air flow meter from the engine bay—unclip and disconnect them carefully.
11. Loosen and remove the lower alternator retaining bolt at the back of the compressor with a 13mm wrench.
12. Remove the remaining alternator retaining bolts (typically two more) with a 13mm wrench.

Step 5: Disconnect and Remove the Alternator

13. Lift the alternator slightly to access the black plastic cover on the back (if equipped) and remove it.
14. Disconnect the electrical wires from the alternator’s rear terminals—note their positions for reinstallation.
15. Pull the alternator out of the engine bay.

Step 6: Install the New Alternator

16. Position the new alternator (944 603 111 00) in the engine bay. If it has a rear cover, ensure it’s in place before securing.
17. Reconnect the electrical wires to the alternator’s rear terminals, matching their original positions.
18. Attach the black plastic cover (if equipped) to the alternator’s back.
19. Install the alternator retaining bolts (three total) but don’t tighten them fully yet.

Step 7: Reinstall the Belt and Tension It

20. Slip the alternator belt (944 102 219 03, if replacing) over the pulleys.
21. Reattach the AC compressor turnbuckle. Pivot the alternator away from the engine to tension the belt slightly.
22. Tighten the turnbuckle by rotating it clockwise until the belt has about 10mm (0.4 inch) of deflection when pressed midway.
23. Tighten the lock nuts on the turnbuckle ends and the retaining bolts on both the alternator and compressor with a 13mm wrench.
24. Fully tighten all alternator retaining bolts to 45 Nm (33 ft-lbs).

Step 8: Reconnect Cooling Duct and Air Box

25. If equipped, reattach the cooling duct hose to the alternator shroud and secure the clamp with a screwdriver.
26. Reinstall the air flow meter and air box, ensuring all clips and connections are secure.

Step 9: Finalize Installation

27. Reattach the skid pan under the engine with the M6 bolts, tightening them with a 10mm (3/8 inch) socket.
28. Reconnect the battery terminals—start with the negative, then the positive.

Post Procedure Checklist

• Start the engine and check that the alternator charges (dash warning light should go off).
• Inspect the belt tension—ensure it deflects about 10mm (0.4 inch) when pressed.
• Check for unusual noises from the alternator or belt area.
• Verify the cooling duct (if equipped) is secure and unobstructed.

Sources

• Clark’s Garage
• Pelican Parts
• Porsche 944 Workshop Manual, Volume 1
• YouTube