Pinpoint Test C: Clutch Pedal Feels Spongy Or Has Excessive Travel/Clutch Will Not Disengage/Clutch System Leakage
Manual Transmission and Clutch
Pinpoint Tests
Pinpoint Test C: Clutch Pedal Feels Spongy or Has Excessive Travel/Clutch Will Not Disengage/Clutch System Leakage
Normal Operation
The clutch is designed to transfer the power from the engine to the transmission, which may be either stationary (starting) or rotating at a different speed (upshifting or downshifting). The clutch is functioning correctly when both the engine and transmission are rotating at the same speed with the clutch engaged. Clutch pedal movement is transmitted by fluid pressure, which actuates the clutch release hub and bearing. The clutch release hub and bearing pushes on the spring center towards the flywheel. The diaphragm spring pivots at the fulcrum, relieving the load on the clutch pressure plate. Steel spring straps riveted in the clutch pressure plate cover pull the clutch pressure plate from the clutch disc, disengaging the engine torque from the transmission.
This pinpoint test is intended to diagnose the following:
- Internal operation
- Clutch pedal reserve
- Clutch slave cylinder travel
- Clutch disc
- Clutch pressure plate
- Clutch pedal free play
PINPOINT TEST C: CLUTCH PEDAL FEELS SPONGY OR HAS EXCESSIVE TRAVEL/CLUTCH WILL NOT DISENGAGE/CLUTCH SYSTEM LEAKAGE
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C1 CHECK THE FLUID LEVEL
- NOTE: Do not check the hydraulic system after the road test. Allow the vehicle to cool down before carrying out the clutch hydraulic system check.
- Remove the brake and clutch reservoir cap.
- Check the fluid level of the brake and clutch reservoir.
- Is the fluid level at or above the step mark?
Yes
INSTALL the reservoir cap. GO to C2 .
No
ADD brake fluid to the specified level. GO to C2 .
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C2 INSPECT THE HYDRAULIC SYSTEM FOR LEAKAGE
- Check the reservoir and reservoir tubes for leakage.
- Check the master cylinder and hydraulic tube for leakage.
- Check the clutch slave cylinder and the hydraulic tube connection for leakage.
- Are there any signs of leakage?
Yes
INSTALL new components as necessary. TEST the system for normal operation.
No
GO to C3.
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C3 CHECK INTERNAL OPERATION
- Remove the reservoir cap.
- Have an assistant slowly depress and release the clutch pedal.
- On the down stroke, the fluid level should not increase by more than 1 mm (0.039 in).
- Does the fluid level increase more than 1 mm (0.039 in)?
Yes
INSTALL a new cylinder master cylinder assembly.
No
GO to C4.
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C4 CHECK THE CLUTCH PEDAL RESERVE
NOTE: The clutch reserve is the distance between the clutch pedal when fully depressed and the position when the vehicle starts to move forward.
- Park the vehicle on a level surface.
- Check for obstructions behind clutch pedal.
- Attach a cable tie to the lower clutch pedal.
- Attach a tape measure to the cable tie.
- Depress the clutch fully and start the vehicle.
- Shift the transmission into 1st gear.
- Use the seam on the steering wheel as a reference point.
- While observing the tape measure, slowly engage the clutch, noting when the vehicle starts to move forward.
- Is the clutch pedal reserve greater than or equal to 25 mm (1 in)?
Yes
The clutch hydraulic system is OK. TEST the system for normal operation.
No
GO to C5.
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C5 CHECK THE CLUTCH PRESSURE PLATE
- Remove the clutch pressure plate.
- Inspect the clutch pressure plate for wear or runout. Refer to Clutch Pressure Plate Check Procedures.
- Are there any signs of excessive wear or runout to the clutch pressure plate?
Yes
INSTALL a new clutch pressure plate.
No
GO to C6.
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C6 INSPECT THE CLUTCH DISC
NOTE: Vehicles equipped with a 4.0L engine use an inner floating damper design disc. When inspecting the disc, a rattle type noise can be heard. This is a normal condition.
- Carry out the clutch disc inspection procedure.
- Is the clutch disc OK?
Yes
GO to C7.
No
INSTALL a new clutch disc. TEST the system for normal operation.
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C7 CHECK CLUTCH PEDAL FREE PLAY
NOTE: The clutch pedal free play is the distance between the clutch pedal when fully released and the position when slight resistance is felt on downward motion.
- Engine OFF.
- Attach a tape measure to the cable tie.
- While observing the tape measure, slowly push downward on the clutch pedal until a slight resistance is felt.
- Is the clutch pedal free play less than 13 mm (0.5 in)?
Yes
The clutch hydraulic system is OK. TEST the system for normal operation.
No
BLEED the clutch hydraulic system. REFER to Clutch System Bleeding Service and Repair. TEST the system for normal operation.
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