Helicopter Noises From Your Car's Engine: What It Means And Why You Should Take Action

Posted on: 2 August 2019

When it comes to unusual engine noises, there's almost always an explanation. In many cases, hearing an abnormal noise from your car engine is indicative of a problem that needs to be repaired. One such situation occurs when you start to hear a rhythmic, deep noise coming from the engine when it's idling. Resembling the sound of helicopter blades, this noise is not something to ignore. Here's what you need to know about it.

Why Does My Car Sound Like A Helicopter?

It can be puzzling to listen to your car at idle and hear a sound that resembles that of helicopter blades whirring. That deep, rhythmic thud of helicopter blades has no place in a car's engine. However, it does happen. And when it does, it's a sign that there's a problem.

In most cases, a noise like that coming from your engine will be timed similarly to the engine's idling rotation or the speed of your engine's cooling fan. There's a reason for that. The noise is typically generated by the fan. More specifically, it's usually generated by the fan clutch. 

What Causes The Helicopter Sound?

The noise you're hearing is a direct result of excess movement in your car's engine cooling fan. Ideally, the fan blades are mounted to the fan clutch and the whole assembly stays secure and stable at all times. However, if the fan clutch is worn, the mounting bolts are damaged, or the unit is otherwise loose, it will allow for forward-and-back movement in the fan. That wobbling movement is what causes the helicopter-like sound.

How Can You Confirm That It's The Fan?

The easiest way to confirm if the fan is the source of the noise is to see if it moves. A clutch-driven cooling fan will spin freely when the engine is off, so that's normal. However, the fan itself shouldn't move forward and backward, meaning toward the firewall in the engine compartment and back. Grab the top of the fan and try to move it back and forth. If there's any play in it, that's the source of your noise.

Why Is A Wobbling Fan A Concern?

You might think that a wobbly fan isn't really a big deal as long as it's still spinning. However, this isn't true. That fan clutch assembly is mounted directly in front of the radiator, and it's connected to the water pump pulley on the other side. If the fan's movement becomes progressively worse, you risk the fan blades puncturing the radiator. Gradually, that fan clutch could not only do that, but it could also fail completely, breaking the fan, the radiator, and possibly your water pump. Then, a simple, inexpensive repair becomes very costly.

If you're hearing a noise like this from your car and there's movement in your fan, contact a repair technician right away to have the fan clutch inspected and replaced. 

For more information on car repairs, especially on cars like BMWs, contact a company like Jim Stephen's Foreign Car Repair.