As a key component of a standard transmission’s clutch assembly, the dual mass flywheel (DMF) helps improve driver comfort, as well as increasing vehicle efficiency. In this technical article, Valeo offers technicians some troubleshooting tips to help diagnose damage, fault and wear.
Firstly, it is important to ascertain that the correct DMF is fitted in accordance to the vehicle’s engine code, and to extract any flash codes or engine faults. The next step is to check that all relevant vehicle systems are operating correctly to confirm they are not the cause. When all checks have been carried out to eliminate any other potential causes, the DMF can be removed and analysed in more detail for signs of fault and wear.
Perception – DMF fails, noise
Problem – Discoloured bluepurple colour on both sides, and/or visible damage
Cause – Very high thermal load
Perception – Noise or impaired starter operation
Problem – Secondary flywheel scores the primary flywheel
Cause – DMF bearing/bushing is worn out
Perception – DMF fails
Problem – Grease egress, sealing cap missing or discoloured brown due to overload
Cause – Thermal overload or mechanical damage/overload
Perception – DMF malfunction, noise
Problem – Burnt residues of abraded lining inside ventilation holes
Cause – Slippage and high thermal load
Perception – Loud humming, vibration
Problem – Balance weight missing (possible to see welding spots)
Cause – Mechanical impact on balance weight
Perception – Frequent noise and difficulty in changing gear
Problem – Folded or incorrectly fitted dowel pins
Cause – Mechanical damage
Perception – Noise when starting the engine
Problem – DMF ring starter gears heavily worn or broken
Cause – Defective starter
Perception – DMF fails
Problem – Strong noise and no torque transmission, Secondary flywheel is blocked or free to rotate at 360˚
Cause – Mechanical damage
Perception – DMF malfunction, friction noise
Problem – Trace of liquid or solid grease from primary flywheel welding
Cause – Defective primary flywheel
Perception – DMF fails
Problem – DMF bearing is damaged
Cause – Wear and/or mechanical impact
Perception – Noise and vibration
Problem – Secondary flywheel free to rotate beyond permissible free movement
Cause – Springs’ loss of effectiveness
