What Causes the Chain Noise During Cold Start of a 2009 Highlander?
2 Answers
Reasons for abnormal noise during cold start: Aging Belt: The generator belt ages, and its rubber material is affected by thermal expansion and contraction. During cold conditions, the belt contracts, and daily rotation stretches it, leading to belt slippage and noise during cold starts. Valve Tappet: Due to the valve tappet, during a cold start, the engine oil is pressurized from the oil pump into the engine oil passages before reaching the valve tappet, resulting in increased noise during cold starts. Lack of Lubrication: The internal gears of the starter lose lubrication, causing sticking and affecting the timely return of the gears. Carbon Brush Failure: The carbon brushes inside the starter motor malfunction.
When I first drove my 2009 Highlander, I often encountered chain noise issues during cold starts. That time, after morning ignition, the chain made a clanking sound like metal friction, but it disappeared after driving for a while when the engine warmed up. Later, I took it to the repair shop, and the mechanic said it was due to the aging timing chain. The cold engine oil was too thick to lubricate in time, causing unstable tensioner pressure and loose chain jumping. After replacing the original chain and tensioner, it became quiet. The timing system of the Highlander is prone to problems, especially in low-temperature areas where the chain wears out quickly. It's recommended not to delay; check the oil pressure and chain gap, otherwise, a broken chain can damage the engine. Using thinner oil in winter can alleviate the issue, but a permanent fix requires early attention. With over a decade of car ownership, such failures are common, and regular maintenance can prevent major troubles.
