What causes a humming sound right after starting the car?
4 Answers
The bearing balls are prone to wear, and the most typical symptoms of bearing wear are car humming sounds and resonance sensations. Here are the specific details: 1. Hub bearing wear: The hub bearing is installed in the suspension's knuckle and constantly bears the vehicle's weight and impact during daily driving, making the bearing balls inside prone to wear. The most typical symptoms of bearing wear are car humming sounds and resonance sensations. It is recommended to replace the hub bearing. 2. Fuel pump operation: When the ignition switch is turned to the ON position, the fuel pump operates for about 3 seconds and then stops. When the engine starts, the fuel pump begins continuous operation. If the engine fails to start, the fuel pump will operate again for about 3 seconds after releasing the ignition key.
I've been driving for over twenty years and have encountered many similar situations. When the car makes a humming sound right after starting, it's likely due to a loose or aged belt. This is especially noticeable in summer, where sometimes there's a friction sound after starting—this is because the alternator belt or air conditioning belt is worn and not running smoothly. If there are other accompanying sounds, like a hiccup-like clicking noise, it might be an issue with the starter, and you should check if the engagement part is loose. Additionally, in winter, metal parts contract due to the cold, making noise at the moment of starting, but it goes away once the engine warms up. I suggest getting it checked at a repair shop as soon as possible. Replacing a belt only costs a few dozen dollars, otherwise, if it snaps one day and leaves you stranded on the road, it would be a real hassle. Safety first—don't underestimate these small unusual sounds; they're often early signs of bigger problems.
I have some basic knowledge about cars. If the car makes a 'hum' sound right after starting, it's likely related to the starting system. For example, the starter gear might be worn or have debris stuck in it, causing a 'click' sound with each start. Another possibility is belt slippage, especially with old drive belts that can produce a 'squeak' sound, more noticeable when the engine is cold. You can do a simple check yourself: turn off the engine, open the hood, and feel the belt for any cracks or check its tension. If the sound persists or worsens, it's best to visit a professional shop for a diagnostic check. Regular maintenance is key—like inspecting belts and water pumps every few tens of thousands of kilometers—to prevent such issues. Ignoring them could lead to starting failures and increase driving risks, so it's better to address them early for peace of mind.
My car occasionally does this too, making a loud noise when starting up, which has made me nervous a few times. I consulted a mechanic who said it might be due to a loose belt or poor starter contact. He suggested simply listening to locate the sound—check the components on the side where the noise comes from when the engine starts. Pay attention to whether the sound becomes more frequent during daily driving. If it happens every time you start the car or even gets louder, it could be a sign of serious wear. It's best to note when it occurs, such as whether it's when the engine is cold or warm, to help with diagnosis during repairs. Don’t delay—fixing small issues saves money and hassle.
