What Causes the Ticking Sound When the Engine is Hot but Not When Cold?
2 Answers
The reasons for the ticking sound when the engine is hot but not when cold are as follows: 1. Loose components in the body: The frequency matches when the engine is hot, or the varying engine speed causes the noise. This type of noise is relatively common and generally not a major issue. 2. Loose components or insufficient lubrication in the transmission: For example, excessive gear meshing clearance. When the clutch is pressed, the power is cut off, and the noise disappears. Other causes of noise inside the car: 1. Brake noise: This is quite common, especially after rain. The noise manifests as a 'squeaking' metal friction sound when the brake pedal is pressed. This is often due to rust on the brake discs, hard particles in the brake pads, or severe wear of the brake pads. The solution is to press the brakes hard a few times to see if it alleviates the noise, followed by checking the brake discs and pads. 2. Tire noise: Tire noise, or road noise, only occurs when the car reaches a certain speed. There are many factors contributing to road noise, including driving speed, tire type, tire pressure, and road conditions. 3. Steering noise: Noise occurs when the steering wheel is turned to its limit. This type of noise is difficult to explain clearly, and the common answer is friction in the tie rod ball joint or rubber boot.
I noticed a ticking sound when the engine is warm, but it disappears when cold. This is usually a common issue caused by thermal expansion of the engine. Specifically, as the engine warms up, components like the valve lifters or hydraulic lifters experience clearance changes—when cold, parts contract reducing gaps and silencing the noise, whereas when hot, expansion increases gaps causing the ticking sound. This is more common in older vehicles or high-mileage cars with valve system issues. Additionally, the timing chain tensioner may age and loosen at high temperatures, causing chain rattling; problems with the exhaust system or belt tension can also lead to unusual noises when the engine is warm. I recommend the owner first check the engine oil level and viscosity, as low oil or old oil can result in insufficient lubrication of the lifters, triggering noise. If left unaddressed, the noise may worsen and cause engine damage. It's best to visit a professional shop to diagnose whether the lifters or chain need replacement to avoid breakdowns and safety risks on the road.
