What Causes the Squeaking Sound When a Car Just Starts?
3 Answers
The reasons for the squeaking sound when a car just starts are: 1. The engine temperature is too low; 2. The three-way catalytic converter expands due to heat; 3. Transmission failure causing internal gear friction; 4. Wear of the engine belt or chain; 5. Wear or system pressure loss in the hydraulic tappet; 6. The clutch pedal return spring is too soft; 7. Worn, loose, damaged bearings or loose fastening nuts. The correct method to start a car is: 1. Insert the key and keep it in the 'lock' position for about 2 seconds; 2. Turn it to the 'on' position and wait for about 5 seconds for the car computer to self-check; 3. Turn the key to the 'start' position to ignite, and release the key after starting; 4. Let the car warm up in place for about 30 seconds to 1 minute; 5. Press the brake, shift to 'D' gear, then release the handbrake and foot brake to start driving.
The car makes a squeaking noise when starting up, and I've encountered this issue several times. As an ordinary person who drives regularly, I think the main culprit is the engine belt: over time, the belt becomes hard, loose, or gets dirty from oil contamination, causing that screeching sound when it slips. This is especially common during cold starts in winter when the rubber contracts. Once, I had noise due to insufficient tension in the air conditioning compressor belt. Simply spraying some belt lubricant can temporarily reduce the noise, but it doesn’t fix the root issue—replace the belt when necessary. Don’t forget to check other components, like the belt pulleys for the alternator or water pump. If they’re worn or have foreign objects rubbing against them, they can also cause squeaking. Addressing this early is crucial because if the belt snaps, it can lead to the fan not spinning, causing the engine to overheat and stall, which is a safety hazard. Checking the belt condition during routine maintenance can save a lot of trouble.
I've assisted many car enthusiasts in addressing squeaky startup issues, and in most cases, it's a problem with the fan belt: aging, looseness, or improper tension can cause squeaking. Cold environments make rubber harder and more prone to slipping, which generates noise. Other potential sources include a dirty or damaged water pump pulley, or a faulty tensioner that fails to keep the belt tight. I recommend first identifying the source of the noise; if it's coming from under the hood, there's a 90% chance it's related to the belt system. Adjusting the tension or replacing the belt usually solves the problem, but avoid constantly using lubricants to mask the issue, as this only provides temporary relief. For safety, it's best to inspect early to prevent belt breakage, which could lead to engine damage.
