Initial Inspection and Diagnostic Overview
Manual Transmission and ClutchInspection and Verification
To guarantee an accurate diagnosis:
^ get an accurate description of the condition.
^ identify when the condition occurs; when hot or cold, during shifting, driving at a particular speed or in a particular gear.
^ have the customer demonstrate the concern, if possible.
^ GO to Symptom Chart - Transmission Clutch and Operation for additional source information and suggested test procedures.
^ carry out the following Noise Evaluation procedures, as necessary. Symptom Chart - Clutch and Transmission Operation
Noise Evaluation
NOTE: Carry out this evaluation with the transmission cold and at normal operating temperature to listen for any change in noise as the transmission warms up.
1. Start the engine.
2. Evaluate the noise in NEUTRAL while the vehicle is parked.
3. Listen for any change in noise while depressing and releasing the clutch pedal.
4. Listen for any change in noise while changing the engine rpm.
5. Drive the vehicle and shift through all of the gear ranges, including reverse. Listen for any change in noise in a particular gear.
6. Drive the vehicle in the gear in which the noise is most noticeable. Depress the clutch pedal and leave the gear engaged. Listen for any change in noise. The vibration of the engine may be amplifying the noise.
7. Drive the vehicle under the same conditions identified in the previous step. Depress the clutch pedal and shift the transmission into NEUTRAL. Release the clutch pedal and allow the vehicle to coast. Evaluate the noise as the rear axle assembly turns the mainshaft.
Noise Evaluation for 4x4 Applications
^ With the vehicle at a complete stop and the transfer case in NEUTRAL, shift the transmission through all of the gear ranges and evaluate the noise at different engine rpm. Check for any noise in NEUTRAL at different engine rpm.
^ Check for any noise change when shifting the transfer case between 2H, 4H, 4L and NEUTRAL.
^ Refer to Four-wheel drive for 4x4 system concerns.
Clutch Slippage Inspection and Verification
1. Chock the wheels.
2. Apply the parking brake.
3. Depress and release the clutch pedal slowly to check if the pedal is binding.
^ If the clutch pedal is not binding, proceed to the next step in this procedure.
^ If the clutch pedal is binding, inspect and repair as necessary. Test the system for normal operation. Proceed to the next step in this procedure, if necessary.
4. Depress the clutch pedal.
5. Start the engine.
6. Shift the transmission to 4th gear.
7. Increase the engine rpm to 2000 and slowly release the clutch pedal. If the engine stalls within 5 seconds, the clutch is not slipping.
^ If the clutch is slipping remove the clutch disc and pressure plate. Refer to Clutch. Inspect the clutch disc and pressure plate for wear and damage. Refer to Clutch Pressure Plate Check and to Clutch Disc Check. Inspect the flywheel for glazing and damage. Check the clutch release hub and bearing for binding and inspect the guide tube. Inspect the input shaft for wear and damage. Repair all components as necessary. Test the system for normal operation. Testing and Inspection Testing and Inspection
Clutch Chatter or Shudder Inspection and Verification
1. Raise and support the vehicle. Refer to Maintenance/Service and Repair.
2. Inspect the engine and transmission mounts for looseness and damage.
^ If the mounts are OK, proceed to the next step in this procedure.
^ If the mounts are loose or damaged, tighten or install new mounts as necessary. Test the system for normal operation. Proceed to the next step in this procedure, if necessary.
3. Check for loose bolts that retain the clutch pressure plate to the flywheel.
^ If the bolts are tightened to specification, proceed to the next step in this procedure.
^ If the bolts are loose, tighten the bolts to specification. Refer to Clutch. Test the system for normal operation. Proceed to the next step in this procedure, if necessary.
4. Remove the clutch disc and pressure plate. Refer to Clutch.
Inspect the clutch disc and pressure plate for wear and damage, and check the clutch disc runout. Refer to Clutch Pressure Plate Check and Clutch Disc Check. Inspect the flywheel for glazing and damage. Check the flywheel runout. Refer to Flywheel Runout Check. Inspect the input shaft for wear, damage and eccentricity. Repair all components as necessary. Test the system for normal operation. Testing and Inspection Testing and Inspection Flywheel Runout Check
Clutch Drag Inspection and Verification
1. Verify that the clutch hydraulic fluid reservoir is filled to the correct level.
^ If the fluid level is correct, proceed to the next step in this procedure.
^ If the fluid level is low, add fluid as necessary. Inspect the clutch hydraulic system for leaks and repair as necessary. Refer to Clutch Controls. Test the system for normal operation. Proceed to the next step in this procedure, if necessary.
2. Depress and release the clutch pedal to check for a spongy pedal.
^ If the pedal feels OK, proceed to the next step in this procedure.
^ If the pedal feels spongy, bleed the clutch hydraulic system. Refer to Clutch System Bleeding - In-Vehicle. Test the system for normal operation. Proceed to the next step in this procedure, if necessary. Clutch System Bleeding
3. Remove the clutch disc and pressure plate. Refer to Clutch. Inspect the clutch disc and pressure plate for wear and damage, and check the clutch disc runout. Refer to Clutch Pressure Plate Check and Clutch Disc Check. Repair all components as necessary. Test the system for normal operation. Testing and Inspection Testing and Inspection
Hard Shifting Inspection and Verification
1. Verify that the clutch hydraulic fluid reservoir is filled to the correct level.
^ If the fluid level is correct, proceed to the next step in this procedure.
^ If the fluid level is low, add fluid as necessary. Check the clutch hydraulic system for leaks, and repair as necessary. Refer to clutch controls. Test the system for normal operation. Proceed to the next step in this procedure, if necessary.
2. Depress and release the clutch pedal to check for a spongy pedal.
^ If the pedal feels OK, proceed to the next step in this procedure.
^ If the pedal feels spongy, bleed the clutch hydraulic system. Refer to Clutch System Bleeding - In-Vehicle. Test the system for normal operation. Proceed to the next step in this procedure, if necessary. Clutch System Bleeding
3. Remove the clutch disc and pressure plate. Refer to Clutch. Inspect the clutch disc and pressure plate for wear and damage. Refer to Clutch Pressure Plate Check and Clutch Disc Check. Check the clutch release hub and bearing for binding and inspect the guide tube. Inspect the input shaft for wear and damage. If all of the components are OK, proceed to the next step in this procedure. Otherwise, repair all components as necessary. Test the system for normal operation.
4. Inspect the transmission housing, shafts, forks and synchronizer assemblies. Refer to M/T - ZF 6 Speed. Repair all components as necessary. Test the system for normal operation. Testing and Inspection Testing and Inspection