What Causes Loud Noise When the Car Fan Runs at High Speed?

[Amanda]

Loud noise from the car's cooling fan is usually caused by deformed fan blades. Here is relevant information: 1. Solution: Replacing individual blades or the entire fan can resolve the issue. If after parking, components like cylinders and piston rings, crankshaft and connecting rods may 'stick' together due to high temperatures. This can cause tightness during the next startup, commonly referred to as 'cylinder seizure or bearing failure'. High-quality fans are designed with oiling holes above the front and rear motor bearings, allowing direct application of car or motorcycle lubricating oil. Generally, oil should be added once a year, about ten drops each time. 2. Reasons for loud noise: Frequent stop-and-go driving can cause engine overheating, triggering the fan as a safety measure. However, if this occurs on highways, it's abnormal. If there's noticeable vibration noise, the fan should be replaced. Many Volkswagen models use single fans, which naturally produce louder noise at high speeds compared to normal operation.