Exhaust System Removal and Installation -2.5L NA

Overview

This procedure outlines the steps to remove and install the exhaust system on all Porsche 944 with an 8-valve engine configuration, covering both pre-1985.5 and 1985.5 onwards variants. The exhaust system includes components like the exhaust manifolds, exhaust pipe, catalytic converter, and muffler. Proper removal and installation ensure optimal engine performance and prevent exhaust leaks. This guide focuses on the manifold-back exhaust system for NA models, excluding turbo-specific crossover pipe procedures.

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Tools Required

• Metric wrench set (10mm to 19mm, 3/8 inch to 3/4 inch)
• Metric socket set (10mm to 19mm, 3/8 inch to 3/4 inch)
• Pry bar
• Penetrating lubricant
• Jack stands
• 5mm (3/16 inch) Allen wrench

Parts Required

• Exhaust flange nuts (6), 944 111 143 00
• Exhaust flange bolts (6), 999 084 052 02
• Exhaust manifold studs (optional, if damaged), 999 062 086 02
• Exhaust manifold nuts (optional, if damaged), 999 084 052 02
• Exhaust hanger bolts and nuts (as needed), 944 111 147 00

Required Additional Procedures

Steps in these procedures are required to complete this process:

• Intake Manifold Removal (for one-piece crossover pipe removal, if applicable)

Step-by-Step Procedure

Step 1: Prepare the Vehicle

1. Park the vehicle on a flat surface and engage the parking brake.
2. Allow the engine and exhaust system to cool completely to avoid burns.
3. Raise the vehicle using a jack and secure it with jack stands at all four corners for safe access to the undercarriage.

Step 2: Disconnect the Oxygen Sensor

4. Locate the oxygen (O2) sensor connector near the firewall at the back of the engine compartment.
5. Disconnect the O2 sensor by unplugging the electrical connector and carefully lower the connector to rest near the exhaust pipe.

Step 3: Remove the CO Sample Tube (If Equipped)

6. Check for the CO sample tube, located at the back of the camshaft housing near the engine lifting ring.

Note: Many Porsche 944s have had the CO sample tube removed and capped due to rust and exhaust leak issues. If capped, skip to Step 4.

7. If present, unscrew the CO sample tube from the exhaust pipe and remove it completely.

Step 4: Detach the Exhaust Pipe from the Exhaust Manifolds

8. Apply penetrating lubricant to the six nuts and bolts connecting the exhaust pipe to the exhaust manifolds to ease removal.
9. Using a 13mm wrench and 13mm socket, remove the six nuts and bolts (three per manifold flange) attaching the exhaust pipe to the exhaust manifolds.
10. Carefully separate the exhaust pipe from the manifolds, ensuring not to damage the flanges.

Step 5: Support and Remove the Exhaust System

11. Place blocks or jack stands under the exhaust system to support its weight and prevent it from falling.
12. Locate the exhaust hangers at three points: in front of the catalytic converter, at the rear of the catalytic converter, and at the rear of the muffler.
13. Using a 13mm wrench and socket, remove the nuts and bolts securing each hanger.
14. Carefully lower the entire exhaust system (exhaust pipe, catalytic converter, and muffler) from the vehicle, ensuring no components are caught or damaged.

Step 6: Remove the Exhaust Manifolds (If Necessary)

15. Determine if exhaust manifold removal is required (e.g., for replacement or inspection). If not, skip to Step 7.
16. Using a 5mm Allen wrench, remove the two Allen head bolts attaching the coolant return pipe to the camshaft housing.

Note: It may be necessary to remove the coolant return pipe completely to access the exhaust manifolds. If so, partially drain the cooling system to avoid coolant loss. Follow the Cooling System Draining procedure in the Porsche 944 Workshop Manual.

17. To remove the exhaust manifold studs, loosen the exhaust nut several turns using a 13mm wrench.

For each stud:
Install a second 13mm nut onto the stud.
Tighten the outer nut against the inner nut while holding the inner nut with a 13mm wrench to prevent it from turning.
Turn the inner nut counterclockwise to back the stud out of the cylinder head.

Note: If the nuts spin on the stud, tighten the outer nut further.

18. Remove the exhaust manifolds from the vehicle.

Step 7: Install the Exhaust Manifolds (If Removed)

19. If the exhaust manifolds were removed, position them back onto the cylinder head.
20. Reinstall the manifold studs by threading them into the cylinder head, using the double-nut method if necessary (reverse of removal).
21. Secure the coolant return pipe to the camshaft housing using the two 5mm Allen head bolts, tightening to 10 Nm (7 ft-lbs).

Note: If the cooling system was drained, refill and bleed it according to the Cooling System Filling and Bleeding procedure in the Porsche 944 Workshop Manual.

Step 8: Install the Exhaust System

22. Raise the exhaust system (exhaust pipe, catalytic converter, and muffler) into position under the vehicle.
23. Secure the exhaust hangers at the three points (front of catalytic converter, rear of catalytic converter, and rear of muffler) using new bolts and nuts, 944 111 147 00, and tighten to 20 Nm (15 ft-lbs).
24. Align the exhaust pipe with the exhaust manifolds and attach using six new nuts, 944 111 143 00, and bolts, 999 084 052 02, tightening to 20 Nm (15 ft-lbs).

Step 9: Reconnect the CO Sample Tube (If Equipped)

25. If the CO sample tube was removed, reinstall it into the exhaust pipe and secure it at the camshaft housing near the engine lifting ring.

Step 10: Reconnect the Oxygen Sensor

26. Reconnect the O2 sensor electrical connector near the firewall.
27. Ensure the connector is secure and the wiring is routed away from hot exhaust components.

Step 11: Finalize Installation

28. Lower the vehicle from the jack stands.
29. Start the engine and check for exhaust leaks at all connections.

Post Procedure Checklist

• Verify no exhaust leaks at the manifold-to-exhaust pipe flanges or hanger connections.
• Confirm the O2 sensor connector is securely attached and wiring is clear of hot surfaces.
• Ensure all bolts and nuts are torqued to 20 Nm (15 ft-lbs) for exhaust flanges and hangers.
• Check that the CO sample tube (if equipped) is properly installed or capped.
• Inspect the exhaust system for proper alignment and clearance from other components.
• If the cooling system was disturbed, verify coolant levels and check for leaks.

Sources

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