What are the reasons for abnormal noise after replacing the timing belt?
2 Answers
Abnormal noise after replacing the timing belt could be caused by the timing belt being too tight, a damaged tensioner pulley, abnormal valve clearance, or misalignment/looseness of the timing pulley. When replacing the timing belt, pay attention to the following 4 points: 1. Selection based on different brands and mileage: The replacement interval varies depending on the brand and mileage, with most vehicles requiring replacement at 60,000-80,000 kilometers; 2. Not all vehicles require timing belt replacement: Not all vehicles need timing belt replacement, as some models never require it; 3. Consider both mileage and service years: In addition to mileage, the vehicle's service years should also be considered. Most vehicles require replacement every three years; 4. Choose authorized manufacturers for replacement: When replacing the timing belt, opt for authorized 4S shops and use genuine parts for safer and longer-lasting performance.
I've been repairing cars for over 20 years and have encountered numerous cases of squealing noises after timing belt replacements. The most common issues are belts adjusted too tight or too loose. New belts require a break-in period, but excessive tension accelerates bearing wear and causes high-frequency noise, while insufficient tension leads to belt slippage with a 'slapping' sound during hard acceleration. Last time, an apprentice at a repair shop failed to replace the tensioner pulley, resulting in a decade-old pulley with disintegrated bearings - the new belt started humming the very next day. When I inspected it, the pulley had noticeable wobble when rotated. Another case involved a customer bringing their own cheap belt with mismatched tooth profile compared to OEM specifications, producing a 'click' sound with every rotation. The worst scenario is improper belt alignment - once saw a Focus with camshaft marks misaligned by two teeth, causing valve tappets to start tapping. Had it not been addressed promptly, the engine would've required major overhaul. Such problems are best left to professionals - always visit a reputable shop to measure crankshaft pulley runout with a dial indicator.
