Heater Core Removal and Replacement

Overview

This guide walks you through removing and replacing the heater core in your Porsche 944 S / S2 with a 16v engine. The heater core is a key part of the heating system, and replacing it can fix issues like leaks or poor heat output. While factory manuals suggest removing the dashboard, this method avoids that, making the job simpler yet still effective. This procedure is based on a late-model Porsche 944 approach, tailored specifically for the 944 S / S2.

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Tools Required

• Stubby Phillips head screwdriver
• Regular Phillips head screwdriver
• Small flat tip screwdriver
• 10mm (3/8 inch) wrench (for the battery negative terminal)

Parts Required

• Heater core for Porsche 944 S2 – 944 573 143 01
• Coolant (compatible with Porsche 944 S2 specifications)

Step-by-Step Procedure

Step 1: Prepare the Vehicle

1. Disconnect the negative battery terminal using a 10mm (3/8 inch) wrench to ensure safety while working.
2. Drain the coolant system to prevent spills. Follow this link to ensure this step – Coolant System Draining – of the process is followed accurately.

Step 2: Remove the Glove Box and Ducting

3. Remove the glove box by unscrewing its fasteners with a Phillips head screwdriver and pulling it out.
4. Disconnect the rubber hose for the thermometer (if your S / S2 has one) and remove the plastic air duct near the glove box area.

5. Locate the lower plastic duct piece under the dashboard. Remove the single screw holding it with a Phillips head screwdriver and take the piece out.

6. Cut the zip-tie securing a wire to the upper duct piece using a small flat tip screwdriver or a cutting tool.

7. Remove the three screws securing the upper duct piece: one near the center and two higher up (as shown by yellow arrows in the original guide). Use a Phillips head screwdriver, then pull the upper duct piece out.

Step 3: Access the Heater Core

8. Place a container (like a Tupperware) under the heater core pipe connections to catch any coolant that spills.

9. Use a small flat tip screwdriver to pry off the two clips on the heater core pipes. Set these clips aside safely—they’ll be reused.

10. Gently pull any vacuum elements or obstructing items (like foam padding) away from the heater core to clear access.

Step 4: Remove the Heater Core

11. Start pulling the heater core out of its housing by hand. It won’t slide out easily due to nearby wiring.

12. Locate the plastic strap holding the wire looms near the core (already removed in the original photos). Undo this strap completely and set it aside.

13. Push and pull the wires gently while tugging the heater core to maneuver it past the wire looms. Some minor damage to the wire loom’s outer covering may occur, but it’s fine as long as the insulation stays intact.

14. Continue working the heater core out until it’s fully removed from its housing.

Step 5: Install the New Heater Core

15. Install the new heater core (944 573 143 01) by reversing the removal steps:
    1. Slide the new core into the housing, maneuvering it past the wire looms.
    2. Reattach the plastic strap to secure the wire looms to the painted stud.
    3. Push the vacuum elements and foam padding back into place.
    4. Reconnect the heater core pipes and secure them with the two clips using a small flat tip screwdriver.
    5. Reinstall the upper duct piece with its three screws and the lower duct piece with its single screw using a Phillips head screwdriver.
    6. Reattach the plastic air duct and thermometer hose (if equipped).
    7. Reinstall the glove box and secure it with its fasteners.
16. Refill the coolant system with fresh coolant compatible with the Porsche 944 S / S2. Follow this link to ensure this step – Coolant System Refilling – of the process is followed accurately.
17. Reconnect the negative battery terminal and tighten it to 10 Nm (7.4 ft-lbs) with a 10mm (3/8 inch) wrench.

Post Procedure Checklist

• Check for coolant leaks around the heater core pipes.
• Start the engine and verify the heater blows warm air.
• Ensure all ducting and the glove box are securely reinstalled with no rattles.
• Confirm the battery terminal is tight and the car starts normally.

Sources

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