What Causes the Abnormal Noise When Starting an Automatic Transmission Engine?
3 Answers
There are many possible causes for engine abnormal noise, as detailed below: 1. If a "ticking" sound comes from the upper part of the engine, with a regular rhythm and frequency increasing with engine speed, this noise mainly originates from the collision between the piston top and the cylinder head. 2. If a "clanking" or "ticking" sound is heard from the side of the engine block during operation, it usually indicates a knocking fault in the engine. 3. If the engine emits a "clanking" sound, it suggests insufficient lubrication between the cylinder and the cylinder liner. 4. If the knocking sound is a "ticking" noise, it likely indicates issues such as piston wear or out-of-roundness.
Last time my colleague's car had the same issue, there was abnormal noise when starting the automatic transmission. It's mostly a problem with the starter or flywheel—worn starter gears can cause a clicking sound. Also, check the belt tensioner; older cars often squeak. The noise is more noticeable in winter due to low temperatures, as the oil hasn't fully circulated, leading to dry friction sounds. I recommend waiting 10 seconds between starts. If the noise persists, get it checked immediately, especially if the battery voltage is below 12 volts, as this can cause more damage. Don’t ignore abnormal noises—early repairs might cost a few hundred yuan, but delaying could mean spending thousands to replace the entire starting system, plus the cost of a tow truck.
As a long-distance driver, I've encountered cold start noise issues. Insufficient battery voltage is the key factor, especially with old batteries over three years old that make the starter struggle to turn. The belt system also requires attention, as cracked alternator belts can slip and squeal. Loose chassis components like exhaust pipe hangers can also cause resonance noise. It's recommended to have annual maintenance checks on the starting system and test battery lifespan. Now I use a lithium battery, which starts quietly even at -20°C – more expensive but durable. Driving safety comes first; don't wait until you're stranded on the road to address issues.
