BMW 740iL engine knocking issue after tune-up and oil change, unresolved problem on BMW 740iL

Some BMW 740iL owners report experiencing engine knocking after a tune-up and oil change, which may be attributed to several potential causes. Low oil levels or the use of incorrect oil types can increase friction between engine components, leading to overheating and knocking. Additionally, issues such as 'rod knock'—the collision between the crankshaft journal and bearing—can also arise. It is essential for owners to use the correct grade of oil as recommended by the manufacturer and adhere to oil change intervals to maintain proper lubrication and prevent knocking. Repairing rod knock can be intricate and costly, with estimates ranging from $2,000 to $3,000. Furthermore, a knocking sound may indicate mechanical damage, such as oil entering the cylinder and fouling the spark plug. If the knocking persists despite recent maintenance, it is advisable for owners to consult a mechanic or BMW specialist for a thorough diagnosis and resolution to prevent further damage and ensure optimal performance.