Dayco – Tensioner Diagnostics

Timing belt automatic tensioner: Metal contamination and oxidation

Causes:

• Contact with contaminating components: oil, dust, leakage of coolant

Actions:

• remove leakage of coolant
• remove leakage of oil and/or fuel
• replace the faulty/damaged component

Timing belt automatic tensioner: Broken central pin

Causes:

• Incorrect setting of the bolt: the torque applied is higher than the value specified on the maintenance sheet.

Actions:

• apply the correct tightening torque
• use the torque wrench
• replace the faulty/damaged component

Timing belt automatic tensioner: Broken stop contact

Causes:

• Incorrect setting of the tensioner: “excessive unload” condition with the belt excessively slack in the transmission
• Incorrect setting of the tensioner: “excessive load” condition with the belt tensioned in the transmission.

Actions:

• replace the components when the engine is cold
• apply the correct tension to the belt
• check the alignment of the reference indexes
• check the belt tension after the adjustment turns
• use the tensiometer to check the belt tension
• replace the faulty/damaged component

Timing belt automatic tensioner: Broken stop contact / Dents on the end stop

Causes:

• Incorrect setting of the tensioner with loss of capacity to modulate and compensate the belt tension variations

Actions:

• replace the components when the engine is cold
• apply the correct tension to the belt
• check the alignment of the tensioner reference indexes
• check the belt tension after the adjustment turns
• replace the faulty/damaged component

Auxiliary belt automatic tensioner: Irregular opening of the aluminium case from the loading arm

Causes:

• High stress
• Load peaks from the belt
• Misalignment
• Binding of the component or other elements in the transmission

Actions:

• use a belt with the correct length for the transmission
• check the alignment between the pulleys
• check the condition of the other components (damper and freewheel)
• replace the faulty/damaged component

Auxiliary belt automatic tensioner: Metal contamination and oxidation

Causes:

• Contact with contaminating components: oil, dust, leakage of coolant

Actions:

• remove leakage of coolant
• remove leakage of oil and/or fuel
• replace the faulty/damage component

Auxiliary belt automatic tensioner: Broken stop

Causes:

• sharp blow due to accidental uncoupling during the installation and/or replacement stage

Actions:

• replace using appropriate tools
• replace the faulty/damaged component