The role of the dual-mass flywheel
The dual-mass flywheel is bolted to the end of the crankshaft, between the engine and the clutch. It consists of two masses connected by springs that absorb engine vibrations, particularly on diesel engines. Over time, these springs and their grease wear out: the two masses develop play and knock against each other.
Signs of a worn dual-mass flywheel
- Metallic rattling at idle, which changes or disappears when you press the clutch pedal.
- Vibrations on start-up and at low revs, felt through the pedal or the floor.
- A knock when the engine is switched off.
- Juddering on acceleration at low revs.
Don't get confused
| Noise | Likely cause |
|---|---|
| Irregular rattling at idle, which changes when you dip the clutch | Dual-mass flywheel |
| Regular humming in neutral, which disappears when you dip the clutch | Gearbox input shaft bearing |
| Noise only with the pedal depressed | Clutch release bearing |
| Rattling or vibrating sheet metal | Exhaust, heat shield, mountings |
Can you keep driving?
Yes, in the short term — but a severely worn dual-mass flywheel can break and damage the clutch, or even the bellhousing. Have it checked sooner rather than later.
What about the gearbox?
The gearbox is not at fault. The flywheel is replaced along with the clutch kit, with the gearbox removed. If the gearbox is also showing signs of wear, a reconditioned exchange gearbox can be fitted during the same job.
