Replacing the heater core on a Series III XJ6 can be a challenging task, often described as a real pain for Jaguar enthusiasts. The factory’s recommended procedure is notoriously time-consuming and complicated:

1. Remove the entire interior of the car.
2. Disassemble the dash and discharge the A/C system.
3. Remove the entire heater and A/C matrix assembly.

For the experienced mechanic, this process can take up to four days. Fortunately, there’s a shortcut that makes this daunting task more manageable for the DIY Jaguar enthusiast!

Step-by-Step Shortcut

Here’s a more efficient method that will allow you to replace the heater core in about 2-3 hours:

1. Begin with the Interior Panels

  • Remove the Left Console and Under Dash Panel: Start by taking off the left console side panel and the left under dash panel. This gives you the necessary access to the heater core area.

2. Deal with the Heater Hoses

  • Open the Hood: Next, open the hood and remove the heater hoses from the firewall. This will let you access the internal parts of the heating system.
  • Clear the Coolant Lines: Carefully use compressed air to blow out the coolant from the lines. This step must be done cautiously to avoid any damage or spillage.

3. Disconnect the Steering Column

  • Remove the Steering Column: Disconnect the steering column at the lower mounting point and remove it from the car. When unbolting the column mounting brackets, make sure to note the placement of any spacers and be gentle to avoid misalignment during reinstallation.

4. Cut the Heater Pipes

  • Trim the Heater Pipes: From inside the vehicle, cut the heater pipes as close to the steel side panels and the coolant temperature sensor as you can, but ensure you leave enough pipe length to attach heater hoses and clamps later.

5. Access the Heater Box

  • Remove the Heater Box Side Panel: Take off the side panel from the heater box, carefully collecting all the small screws as you go. Organization is key here to ensure a smooth reassembly process.

6. Disconnect Components

  • Remove Lever Rods and Electrical Connections: Detach the lever rods and electrical connections from the side of the heater box. It’s a good idea to take pictures or detailed notes of their positions to ensure you can reconnect everything correctly later on.

7. Replace the Heater Core

  • Extract the Old Heater Core: Slide out the old heater core from the heater matrix box.
  • Prepare the New Heater Core: Cut the pipes of the new heater core to match the same spots as the old one. Slide two pieces of 9/16″ heater hose (each 2″ long) with hose clamps onto the pipes.

8. Install the New Core

  • Insert the New Heater Core: Push the new heater core into the heater matrix box, ensuring the hoses are in the correct position. Reattach the side panel, rods, and electrical connections, paying close attention to your notes and photos.

9. Final Assembly

  • Tighten and Test: Tighten the hose clamps securely. Reassemble the panels and reattach the coolant hoses. Fill the system with coolant and perform a pressure test to ensure there are no leaks.

Additional Tips

  • Annual Check-Up: Once installed, it’s wise to check the tightness of the hose clamps annually. This helps prevent any leaks or issues over time.
  • Be Patient: While this shortcut saves time, it still requires care and attention to detail. Take your time, and don’t rush the process.

Conclusion

By following this shortcut, you can bypass the lengthy factory procedure and replace the heater core efficiently. This method is ideal for the DIY Jaguar enthusiast who loves getting hands-on with their vehicle and prefers a practical approach to maintaining their beloved Series III XJ6.

Enjoy the satisfaction of completing the job yourself and saving time in the process! Happy wrenching! 🛠️

See our Jaguar Parts Store Catalog to order parts.