Lexus GX460 rattling noise resembling timing chain on cold start on Lexus GX460

Some Lexus GX460 owners report experiencing a rattling noise that resembles a timing chain sound during cold starts, which may indicate potential issues with the timing chain system. This rattling sound is often a warning sign of a worn timing chain, particularly noticeable when oil pressure is at its lowest, leading to excess slack. Additionally, a faulty timing chain can create an unpleasant metallic rattle during acceleration or deceleration, signaling the need for replacement. Owners may find that the most common sound associated with a bad timing chain tensioner is a rattling noise during startup, before oil pressure builds up. To diagnose these issues, some owners use a stethoscope on the timing chain cover, where a rattling or scraping sound can indicate a problem. It is recommended that owners consult a professional mechanic for a thorough diagnosis, as prompt attention to these unusual noises is crucial to prevent potential engine damage and ensure the vehicle's proper functioning.