Intake Manifold Removal and Installation – 2.5L NA

Overview

This guide provides step-by-step instructions for removing and installing the intake manifold on all Porsche 944 variants with an 8-valve engine, covering pre-1985.5 and 1985.5 onwards variants. The intake manifold directs air into the engine’s cylinders, and this procedure is essential for maintenance tasks like gasket replacement or accessing other engine components.

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Tools Required

• 10mm (3/8 inch) socket and ratchet
• 12mm (1/2 inch) socket
• 10mm (3/8 inch) open-end wrench
• Long 6mm (1/4 inch) Allen head socket or long 6mm hex key
• Flat-tip screwdriver
• Rubber mallet
• Scraper

Parts Required

• Intake manifold gaskets (4) – 944 110 147 03

Required Additional Procedures

Steps in these procedures are required to complete this process:

• Fuel Injector and Fuel Rail Removal and Installation
• Allen Head and Cheesehead Bolt Removal

Step-by-Step Procedure

Step 1: Prepare the Vehicle

1. Disconnect the negative battery lead to ensure safety during the procedure.
2. Remove the spark plug wires from the spark plugs and move them out of the way to access the intake manifold.

Step 2: Remove the Fuel Rail and Injectors

3. Follow this link to ensure this step – Fuel Injector and Fuel Rail Removal and Installation – of the process is followed accurately.

Step 3: Disconnect the Air Intake Hose

4. Remove the air intake hose connecting the air flow sensor to the throttle body.

Step 4: Disconnect Throttle Body Components

5. Disconnect the vacuum hose from the throttle body.
6. Disconnect the electrical connector from the throttle position switch.

Step 5: Remove the Oil Dipstick Tube Bolt

7. Using a 10mm socket, remove the bolt securing the oil dipstick tube to the intake manifold.

Step 6: Disconnect Hoses and Cables

8. Disconnect all accessible vacuum hoses from the intake manifold.

For Pre-85.5 models:
Some vacuum hoses underneath the intake manifold cannot be disconnected until the manifold is lifted.

9. At the rear of the intake manifold, loosen the retaining bolt for the speed and reference sensor electrical connector mounting bracket using a 10mm open-end wrench, then slide the bracket off.
10. Disconnect the throttle cable from the throttle body.
11. If equipped, disconnect the cruise control cable from the servo unit near the battery tray. Remove the cable clamp securing the cruise control cable to the top of the intake manifold and move the cable aside.

Step 7: Loosen the Intake Manifold Brace

For Pre-85.5 models:
Using a 12mm socket, remove the intake manifold brace bolt located to the right of the throttle body near the brake booster hose connection.
For 85.5 Onwards models:
Using a 12mm socket, loosen (but do not remove) the intake manifold brace bolt located to the left of the throttle body under the front edge of the manifold.

Step 8: Remove the Intake Manifold Bolts

12. Using a long 6mm Allen head socket or 6mm hex key, remove the eight M8 Allen head bolts securing the intake manifold to the cylinder head.• These bolts may be tightly bonded to the cylinder head. To avoid stripping, follow this link to ensure this step – Allen Head and Cheesehead Bolt Removal – is followed accurately.

Step 9: Lift the Intake Manifold

13. If the intake manifold does not lift off easily, gently strike it with a rubber mallet to break it free.

For Pre-85.5 models:
Lift the intake manifold slightly and disconnect the vacuum hoses underneath before fully removing it.

14. Remove the intake manifold from the vehicle.

Step 10: Protect the Cylinder Head

15. If performing additional work, cover the cylinder head intake ports by stuffing clean rags into them or sealing them with duct tape to prevent debris entry.

Step 11: Prepare for Installation

16. Using a scraper, carefully remove the old intake manifold gaskets from the cylinder head and intake manifold, ensuring not to scratch the mating surfaces.
17. Apply a small amount of grease to the new intake manifold gaskets (944 110 147 03) to hold them in place, then install them onto the cylinder head. Ensure correct gasket orientation: the gasket for cylinder #1 may differ from cylinders #2, #3, and #4 to avoid obstructing the injector flow path.

Step 12: Install the Intake Manifold

For Pre-85.5 models:
Lower the intake manifold into position, connecting the vacuum hoses underneath as it is set onto the cylinder head.
For 85.5 Onwards models:
Lower the intake manifold, ensuring the brace bolt slides into the “U” of the intake manifold brace.

18. Install the eight M8 Allen head bolts and torque to 20 Nm (15 ft-lbs) using a 6mm Allen head socket.
19. Torque the intake manifold brace bolt (M8) to 20 Nm (15 ft-lbs) using a 12mm socket.

Step 13: Reconnect Components

20. Connect the fuel supply and return lines to the fuel rail.
21. Connect the vacuum lines to the fuel damper and fuel pressure regulator.
22. If equipped, reconnect the cruise control cable to the servo unit.
23. Reconnect the throttle cable to the throttle body.
24. Connect the vacuum line to the throttle body and the electrical connector to the throttle position switch.
25. Reattach the speed and reference sensor mounting bracket to the rear of the intake manifold using a 10mm open-end wrench.
26. Connect all remaining vacuum hoses to the intake manifold.
27. Using a 10mm socket, install the oil dipstick tube mounting bolt to the intake manifold.

Step 14: Install the Air Intake Hose

28. Install the air intake hose between the air flow sensor and the throttle body.

Step 15: Install the Fuel Rail and Injectors

29. Follow this link to ensure this step – Fuel Injector and Fuel Rail Removal and Installation – is followed accurately, routing and connecting the spark plug wires during installation.

Post Procedure Checklist

• Check for fuel leaks around the fuel rail and injectors as described in the Fuel Injector and Fuel Rail Removal and Installation procedure.
• Verify all vacuum hoses are securely connected with no leaks.
• Ensure the throttle cable and cruise control cable (if equipped) operate smoothly.
• Confirm the intake manifold bolts and brace bolt are torqued to 20 Nm (15 ft-lbs).
• Inspect the cylinder head intake ports for cleanliness before starting the engine.

Sources

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