Indicator:

Slipping clutch/Incorrect clutch operation

Cause:

1. Bell housing has not been degreased and cleaned. Poor installation of the new clutch. The new clutch disc has not worn but fibres have become lodged in the new clutch cover are that of the previously worn clutch. It is a requirement due to ventilation designs that the bell housing area free from old fibres, dirt and grease when installing new clutch.
2. This problem is common in 4 wheel drive vehicles when an inspection cover or a clutch fork cover boot has not been Inspected for re-use or replaced when installing a new clutch.

Effect: 

Worn clutch disc facing fibres and/or dirt lodged between diaphragm spring and clutch cover housing causing loss of cover clamping force.

Action:

1. Ensure the bell housing and back of the engine are thoroughly degreased and cleaned of foreign material before installing a new clutch.
2. Ensure inspection locations are sealed correctly with any boots thoroughly inspected for re-use and if necessary replaced. (Note: These problems are common on farm vehicles, vehicles travelling on sand and 4x4 recreational vehicles.)