Troubleshooting Troubleshooting – Manual Transmission Estimated reading: 4 minutes Contributors Overview This troubleshooting guide is designed to help identify and address manual transmission issues specific to the Porsche 944 S / S2 (16v, 1989–1991). It covers common symptoms such as rattles, noises, and shifting difficulties, focusing on components relevant to the S / S2’s transaxle and drivetrain. Proper diagnosis is critical to maintaining the performance and reliability of your S / S2’s manual transmission, ensuring smooth operation and longevity. Pink and blue text represents links to additional resources, tools, parts, and partner websites. Rattle from the Rear at Low RPM Possible Causes Checks Procedure 5th Gear This is a known issue in the S / S2’s transaxle, where 5th gear has more clearance and play on the mainshaft, causing a rattle at low RPM. The type of transaxle fluid impacts noise levels. Synthetic gear oil can reduce or eliminate the rattle. Use a high-quality synthetic gear oil to minimize noise. No specific repair procedure is available, as this is a design characteristic. Noise from Drivetrain with Engine Idling and Clutch Pedal Depressed Possible Causes Checks Procedure Clutch Release Bearing or Pilot Bearing High-pitched squealing or grating noise. Diagnosis requires clutch disassembly, as no definitive test exists without inspection. Follow the Clutch Replacement procedure (CLUTCH-01) to inspect and replace bearings. Exhaust other causes first due to the procedure’s complexity. Noise from Drivetrain with Engine Idling, Clutch Pedal Not Depressed, and Transmission in Neutral Possible Causes Checks Procedure Clutch Disc If equipped with a rubber-centered clutch, degradation can cause a thumping noise. Diagnosis requires clutch disassembly. Use the Clutch Replacement procedure (CLUTCH-01) to inspect and replace the clutch disc. Clutch Release Bearing or Pilot Bearing High-pitched squealing noise. Use a mechanic’s stethoscope to narrow down the source, but confirmation requires disassembly. Follow the Clutch Replacement procedure (CLUTCH-01) to inspect and replace bearings. Torque Tube Bearings High-pitched squealing or grating noise. Use a mechanic’s stethoscope to pinpoint the noise source. Replace or rebuild the torque tube using the Torque Tube Removal, Rebuild, and Installation procedure (TRANS-05). Drive Shaft to Transaxle Input Shaft Coupling Rare issue where loose coupling bolts cause rattling, often after clutch replacement. Check bolt torque. Inspect and retorque coupling bolts to specifications. Transaxle Input shaft bearing noise is rare but possible. Diagnosis is challenging without disassembly. Rebuild the transaxle at a professional shop if confirmed. Noise from Drivetrain During Normal Driving Before troubleshooting, idle the car with the clutch engaged and transaxle in neutral. If no noise is present, rule out clutch disc, release/pilot bearings, torque tube bearings, and transaxle input shaft coupling. Possible Causes Checks Procedure CV Joints Common cause of rear-end noise due to insufficient lubrication, even with intact boots. Rebuild or repack CV joints using the CV Joint General Information, Removal, Installation, and Maintenance procedure (SUSP-01). Rear Wheel Bearings Noise changes pitch or appears/disappears during cornering, indicating worn bearings. Replace bearings using the Rear Wheel Bearing Replacement – Aluminum Trailing Arms procedure (SUSP-11). Transaxle If CV joints and wheel bearings are ruled out, check transaxle bearings (e.g., needle bearings, four-point ball bearing, or flange shaft roller bearings). Rebuild transaxle at a professional shop, as axle flange shaft bearings require special tools. Transmission Difficult to Shift or Will Not Engage into Gear Possible Causes Checks Procedure Clutch Disc Refer to Troubleshooting – Clutch (TS-04). Follow TS-04 procedure. Pressure Plate Refer to Troubleshooting – Clutch (TS-04). Follow TS-04 procedure. Transaxle Worn synchros, especially in 2nd or 3rd gear, cause difficult shifting, worse when cold. Synthetic gear oil may improve symptoms. Use synthetic gear oil for temporary improvement; rebuild transaxle for a permanent fix. Shift Lever or Shift Linkage Inspect for wear or looseness in the shift lever or linkage. Repair or replace using the Shift Lever and Shift Linkage procedure (TRANS-07). Sources Clark’s Garage Pelican Parts Porsche 944 Workshop Manuals YouTube Tagged:Manual Transmission Troubleshooting Troubleshooting – Manual Transmission - PreviousTroubleshooting – Heating, Ventilation, and Air Conditioning (HVAC)Next - Troubleshooting – Manual TransmissionTroubleshooting – Suspension and Steering
