Odometer Repair

Overview

This procedure guides you through repairing the odometer on your Porsche 944 (16v engine), a common issue often caused by resetting the trip odometer while the vehicle is moving. A faulty odometer may stop recording mileage due to a disengaged, worn, or broken drive gear. This repair is crucial for maintaining accurate mileage tracking, which is important for resale value and vehicle maintenance records. The process involves removing the gauge cluster, accessing the speedometer, and fixing or replacing the odometer gear.

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Tools Required

• Phillips head screwdriver
• Small flat tip screwdriver
• Jeweler’s screwdriver or small paper clip

Parts Required

• New odometer drive gear (if broken) – 20 x 21 tooth gear (most common for 944) or 20 x 22 tooth gear (less common; verify after disassembly)
• Crazy Glue (for securing a disengaged gear)

Required Additional Procedures

Steps in these procedures are required to complete this process:

• Removing Late 944 (1985.5 and newer) Gauge Cluster

Step-by-Step Procedure

Step 1: Remove the Instrument Cluster

1. Follow this link to ensure this step – Removing Late 944 (1985.5 and newer) Gauge Cluster – of the process is followed accurately. This will give you access to the speedometer on your Porsche 944.

Step 2: Disassemble the Speedometer

2. Remove the gauge cluster front cover by unscrewing the nine Phillips head screws along the back edge of the cluster.

3. Locate and remove the four screws on the back of the instrument cluster directly behind the speedometer.

4. Gently pull the speedometer out of the gauge cluster chassis.

Step 3: Inspect the Odometer Gear

5. Hold the speedometer with the back facing you and look at the left side for a white plastic worm gear (it resembles a screw).
6. Check the gear engaging the worm gear. This is the odometer drive gear. It may have slid off its shaft, be worn (teeth no longer grip), or be broken.

Step 4: Repair a Disengaged Gear (If Applicable)

7. If the gear has slid off but isn’t damaged, use a small flat tip screwdriver to slide it back along its shaft until it engages the worm gear.
8. Apply a small drop of Crazy Glue where the shaft passes through the gear to secure it and prevent future sliding.
9. If the gear is intact and now engaged, skip to Step 7 to reassemble. If it’s worn or broken, proceed to the next step.

Step 5: Disassemble Further to Replace a Worn or Broken Gear

10. Obtain a replacement gear (20 x 21 tooth gear is standard for most 944 models; some use 20 x 22 tooth gear). Confirm the tooth count after disassembly.
11. Gently pry up the speedometer needle to remove it from its shaft. (The 944’s electronic speedometer lacks a mechanical stop at 0 mph (0 km/h), so no need to mark a stop position.)
12. Remove the two screws securing the face plate on the speedometer.
13. Lift off the face plate, then remove the four screws underneath to separate the speedometer into two halves.
14. Locate the odometer gears inside. Remove them in order, starting with the gear furthest from the damaged one:
15. Use a jeweler’s screwdriver or paper clip to push out the pin holding the first gear.
16. Remove the e-clips securing the remaining gears (note: reattaching e-clips can be tricky).

Step 6: Replace the Odometer Gear

17. Remove the worn or broken gear and install the new one in its place.
18. Reattach the e-clips and pin to secure all gears, working in reverse order of removal.

Step 7: Reassemble the Speedometer and Cluster

19. Rejoin the speedometer halves and tighten the four screws under the face plate.
20. Reattach the face plate with its two screws.
21. Press the needle back onto its shaft, aligning it to its resting position (typically 0 mph (0 km/h)).
22. Place the speedometer back into the gauge cluster chassis and secure it with the four screws on the back.
23. Reattach the gauge cluster front cover using the nine Phillips head screws.
24. Reinstall the instrument cluster by reversing the steps in Removing Late 944 (1985.5 and newer) Gauge Cluster.

Post Procedure Checklist

• Turn on the ignition and verify that the speedometer needle moves smoothly.
• Drive the vehicle 5 miles (8 km) to confirm the odometer records mileage accurately.
• Check that the trip odometer resets correctly when the vehicle is stationary.

Sources

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