What is the reason for the abnormal noise when stepping on and releasing the clutch?
3 Answers
The reason for the abnormal noise when stepping on and releasing the clutch is the lack of lubricating oil in the return spring of the clutch pedal. The working process of the clutch involves the following three points: Working process: The diaphragm spring is installed between the clutch cover and the pressure plate, creating a pre-compression deformation that generates pressure on the pressure plate, pressing the driving and driven parts of the clutch together, i.e., the clutch is in the engaged state; Separation process: When the clutch pedal is depressed, the pedal moves left, pushing the push rod left, which through the cylinder and working cylinder, moves the diaphragm spring separation plate left. This causes the diaphragm spring to pivot on the support pin fixed to the clutch cover, moving the large end to the right while pulling the pressure plate right via the separation plate; Engagement process: Releasing the clutch pedal returns the pedal to its original position. The movement of the engagement mechanism is the reverse of the separation process. When a preset gap appears between the release bearing and the diaphragm spring separation plate, and the diaphragm spring re-presses the pressure plate against the driven plate, the engagement process ends, and the clutch resumes its power transmission function.
With over a decade of driving experience, I've found that abnormal noises when engaging and disengaging the clutch are mostly caused by issues with the release bearing. When depressed, the bearing bears pressure and tends to squeak when worn, especially noticeable during cold starts. If there's a gurgling sound upon release, it might indicate wear on the pressure plate or an uneven flywheel, leading to abnormal friction. Worn clutch discs or aged springs can also cause rattling noises, particularly in high-mileage vehicles. Insufficient lubrication is another major factor, such as when transmission oil becomes thin or is lacking, which can exacerbate friction sounds. Whenever I encounter this situation, I always remind myself not to ignore it and to get it checked promptly to prevent minor issues from turning into major failures, as clutch repairs can be quite costly. Shifting gears gently in daily driving can also extend its service life and reduce the risk of abnormal noises.
I've encountered this kind of abnormal noise several times while driving my manual transmission car. It's usually caused by insufficient oil in the clutch slave cylinder or failure of the release bearing. A sharp sound when pressing and a dull sound when releasing indicates poor bearing lubrication or pressure plate damage. Clutch disc wear is also quite common, especially after several years of driving. When the discs become thin, abnormal friction occurs, leading to creaking sounds. I've also noticed that if the operation is too heavy or too abrupt, it can easily cause uneven stress on the system, increasing noise. It's important to pay attention to driving habits - gently pressing and slowly releasing can reduce the probability of faults. It's best to go to a repair shop for pressure testing and inspection for peace of mind and safety. Don't forget to check the transmission oil level - low oil can also cause noise. This is a trick I learned from experienced drivers.
