Motor Mounts – Replacing – 2.5L NA

Overview

This procedure outlines how to replace the motor mounts on all Porsche 944 with a 8 valve engine configuration, covering both pre-1985.5 (83-85.5) and 1985.5 onwards (86-88) variants. Motor mounts secure the engine to the chassis, reducing vibration and ensuring stability. Replacing worn mounts improves engine alignment and ride quality. The process involves lifting the engine slightly, removing the old mounts, and installing new ones, with specific bolt lengths for each model variant.

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Tools Required

• Jack stands
• Floor jack
• Pry bar
• Metric socket set (10mm, 13mm, 19mm)
• Metric wrench set (13mm, 17mm)
• Torque wrench
• M8 tap (optional, for thread chasing)

Parts Required

• Motor mounts (2): 951 375 042 04
• Bolts (8 x 38 mm): 900 378 024 02
• Bolts (8 x 42 mm): 900 378 034 02
• Washers (4): N 015 401 3

Required Additional Procedures

Steps in these procedures are required to complete this process:

• Front Sway Bar Removal

Step-by-Step Procedure

Step 1: Prepare the Vehicle

1. Loosen the lug nuts on the front wheels using a 19mm (3/4 inch) socket, turning them several times but not removing them.
2. Raise the vehicle and secure it on jack stands at the designated jacking points.
3. Remove the front wheels by fully unscrewing the lug nuts and pulling the wheels off.
4. Remove the belly pan by unscrewing its fasteners (typically 10mm bolts).

Step 2: Remove the Front Sway Bar

5. Follow this link to ensure this step – Front Sway Bar Removal – is followed accurately.

Step 3: Remove Motor Mount Heat Shields

6. Locate the motor mount heat shields on both sides of the engine.
7. Remove the M6 bolts securing the heat shields using a 10mm (3/8 inch) socket.

Step 4: Remove Lower Motor Mount Lock Nuts

8. Locate the lower motor mount lock nuts beneath the mounts on both sides.
9. Remove the M6 lock nuts using a 17mm (11/16 inch) open-end wrench.

Step 5: Remove Upper Motor Mount Bolts

10. Access the upper motor mount bolts, which are challenging to reach. Use a flex-head ratchet with a 13mm (1/2 inch) socket or a short 13mm (1/2 inch) wrench.

For Pre-85.5 models:
If the mounts are full rubber, hold the nut on the bottom of the mount with a second 13mm (1/2 inch) wrench while loosening the bolt.

For 85.5 Onwards models:
No additional wrench is needed, as newer mounts typically have integrated nuts.

Step 6: Lift the Engine

11. Place a 12 inch x 12 inch (30 cm x 30 cm) piece of plywood on the floor jack pad to distribute weight evenly.
12. Position the jack under the oil pan and raise the engine just enough to relieve tension on the motor mounts (approximately 5-10mm or 0.2-0.4 inches).

Step 7: Loosen Cross-Member Bolts

13. Use a sharp object (e.g., awl) to scribe a mark around the four cross-member mounting bolts on each side for alignment during reassembly.
14. Loosen the cross-member bolts (M12) using a 19mm (3/4 inch) socket until they are nearly removed. Remove each bolt one at a time, then thread it back in two turns to keep the cross-member in place.

Step 8: Remove Old Motor Mounts

15. With the engine slightly raised and cross-member loosened, slide the old motor mounts out. Twist the mounts to free them from the cross-member pocket.

If needed, use a pry bar to lift one side of the engine slightly (about 10mm or 0.4 inches) to create clearance.

Step 9: Prepare New Motor Mounts

16. (Optional) Chase the threads in the new motor mount bolt holes using an M8 tap to ensure clean threads, as some OEM mounts may have shallow threading.

Step 10: Install New Motor Mounts

17. Slide the new motor mounts (951 375 042 04) into the cross-member pockets, twisting as needed to align.

For right side (both models):
Install two M8 x 38 mm bolts (900 378 024 02) with washers (N 015 401 3). Do not reuse old spacer washers with new-style mounts.

For left side:

Pre-85.5 models:
Measure the thickness of the ledge at the bottom of the left-side mounting bracket. If 21mm (0.83 inches), use two M8 x 38 mm bolts (900 378 024 02) with washers (N 015 401 3). If 25mm (0.98 inches), use two M8 x 42 mm bolts (900 378 034 02) with washers (N 015 401 3).

85.5 Onwards models:
Follow the same measurement process for the left-side bracket to select the appropriate bolt length.

Step 11: Reassemble Components

18. Tighten the cross-member bolts to 85 Nm (62 ft-lbs) using a torque wrench and 19mm (3/4 inch) socket, aligning with the scribed marks.
19. Install the upper motor mount bolts and tighten to 23 Nm (17 ft-lbs) using a 13mm (1/2 inch) socket.
20. Install the lower motor mount lock nuts and tighten using a 17mm (11/16 inch) wrench.
21. Reinstall the motor mount heat shields with M6 bolts, tightening with a 10mm (3/8 inch) socket.
22. Follow this link to ensure this step – Front Sway Bar Removal – is followed accurately in reverse to reinstall the sway bar, tightening bolts to 23 Nm (17 ft-lbs).
23. Reinstall the belly pan, securing with its fasteners (typically 10mm bolts).
24. Reinstall the front wheels and hand-tighten the lug nuts.
25. Lower the vehicle from the jack stands.
26. Tighten the lug nuts to 130 Nm (96 ft-lbs) using a torque wrench and 19mm (3/4 inch) socket.

Post Procedure Checklist

• Verify all bolts (sway bar, motor mounts, cross-member) are torqued to specifications: sway bar and upper motor mount bolts to 23 Nm (17 ft-lbs), cross-member bolts to 85 Nm (62 ft-lbs).
• Check cross-member alignment with scribed marks and inspect for cracks or damage.
• Ensure no tools or debris are left under the vehicle.
• Start the engine and listen for unusual vibrations or noises, indicating improper mount installation.
• Check for leaks around the oil pan after jacking.

Sources

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