Pinpoint Test G: Excessive Noise

Manual Transmission and Clutch






Pinpoint Tests

Pinpoint Test G: Excessive Noise

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:
- Transmission
- Clutch slave cylinder
- Pilot bearing



PINPOINT TEST G: EXCESSIVE NOISE

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G1 TRANSMISSION NEUTRAL GEAR ROLLOVER TEST


- Start the engine and let it idle with the transmission in NEUTRAL and the clutch engaged (pedal up). If noise is excessive, depress the clutch pedal to stop the transmission input shaft from rotating.
- Does the noise stop when the clutch pedal is depressed?

Yes
INSPECT the clutch components for damage. REFER to General Procedures.

No
GO to G2.

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G2 CHECK THE CLUTCH SYSTEM


- Engine OFF.
- Using slow, medium, then fast strokes, depress and release the clutch pedal.
- Is there a squeak?

Yes
GO to G3.

No
The clutch system is OK. VERIFY customer concern.

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G3 CHECK THE STARTER INTERLOCK SWITCH


- Remove the starter interlock switch. Using slow, medium, then fast strokes, depress and release the clutch pedal.
- Is there a squeak?

Yes
REINSTALL the starter interlock switch. GO to G4 .

No
INSTALL a new starter interlock switch.

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G4 CHECK THE CLUTCH SLAVE CYLINDER


- Remove the transmission.
- Inspect the clutch slave cylinder for wear or loss of lubrication.
- Are there any signs of wear or loss of lubrication?

Yes
INSTALL a new clutch slave cylinder.

No
GO to G5.

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G5 CHECK THE PILOT BEARING


- Inspect the pilot bearing for wear or damage.
- Is the pilot bearing OK?

Yes
GO to G6.

No
INSTALL a new pilot bearing.

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G6 CHECK THE TORSION SPRINGS


- Inspect the torsion springs for fatigue or breakage.
- Are there any signs of fatigue or breakage?

Yes
INSTALL a new clutch disc. TEST the system for normal operation.

No
INSPECT the crankshaft end play.

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