Growling or grating clutch noise is heard when your car clutch pedal is fully depressed.
Car Problem Diagnosis
When your car clutch pedal is fully depressed, throwout bearing is forces to press against the pressure plate by a clutch linkage. When these happened the pressure plate moves from the clutch disc in turn will disengage the clutch. If a clutch pedal is fully depressed the throwout bearing will continue to rotate, since the throwout bearing rotates it will then produce a noise if the bearing is faulty. The noise that produced by these faulty bearing is a growling or grating clutch noise that you have heard.
Possible Cause of Clutch Noise When Pedal is Depress
Faulty Throwout Bearing
All About Auto Recommendation
Transmission is very complex parts, there is no other way to fixed the problem rather than bringing your car to a reputable auto repair shop and ask the mechanic to inspect the transmission assembly, probably the mechanic will opened up the transmission assembly to better examined what causes the problem. This kind of work can cost you a lot, however if your car is covered by a warranty no need to worry about, if not then you’ll have to shop around for a cheaper repair shop but off course does a good quality job.