Why does the Corolla fail to start and make abnormal noises?

[McTucker]

The reasons why the Corolla fails to start and makes abnormal noises are as follows: Low battery voltage: You can turn on the headlights and some electrical devices to check whether the dashboard and interior lighting dim during the starting process. If they do dim, it indicates insufficient battery voltage. Excessive carbon buildup in the intake manifold: Excessive carbon buildup in the throttle valve, idle speed motor, etc., prevents the engine's air-fuel mixture from reaching the required ratio, causing the vehicle to fail to start. The repeated engagement of the magnetic coil and starter relay produces a clicking sound. Insufficient fuel supply in the fuel system: This phenomenon is similar to excessive carbon buildup in the intake manifold, also preventing the engine from achieving the required air-fuel mixture ratio, leading to the vehicle's failure to start. Starter motor or related circuit malfunction: The magnetic coil cannot maintain engagement and fails to provide starting torque, resulting in the engine's inability to start and producing a clicking sound. Ignition system malfunction: This directly causes the engine to fail to start. If the ignition key remains in the starting position, the starter relay repeatedly engages, also producing a clicking sound.

[McJudah]

My Corolla also had an issue with abnormal noise during ignition last week, with a particularly harsh clicking sound. Later inspection revealed that the starter gear and flywheel weren't engaging properly, like two gears grinding against each other without meshing. This usually happens with older cars, especially during cold starts when the lubricant between gears solidifies. I'd suggest trying to press the accelerator pedal a few times before ignition to pressurize the fuel system. If that doesn't work, you'll need to tow the car - don't force the ignition and risk breaking the gears. These problems are most common in winter. Since then, I've made a habit of straightening the steering wheel after parking, as I've heard it reduces strain on the starter.

[SanGarrett]

Last time I drove my Corolla to the supermarket, when I turned the key, I heard a long squealing sound, and the dashboard lights dimmed. The mechanic said it was a sign of a weak battery, where the starter couldn't turn the crankshaft, causing the belt to spin and slip. You can first check the brightness of the interior dome light; if the horn sounds muffled, it's likely a battery issue. Nowadays, car batteries only last about two to three years. I've since learned my lesson and always keep a portable jump starter in the car. By the way, if the battery terminals are covered with white crystalline deposits, it can also cause poor contact—pouring hot water on them can temporarily fix the issue.

[MollyMarie]

My decade-old Corolla suddenly made loud banging noises like someone was hammering the engine when starting last month. After towing it to the dealership, mechanics found a broken valve rocker arm upon disassembly. The technician said long-term failure to change engine oil would cause sludge to clog oil passages, leaving hydraulic lifters without lubrication. This situation requires immediate engine shutdown, otherwise fragments falling into cylinders could completely destroy the engine. They recommended paying attention to oil viscosity during next maintenance, suggesting 5W-40 for older vehicles. Now I've developed the habit of turning on the ignition to let the oil pump work for ten seconds before each cold start.

[OJohnny]

At the beginning of the year, my hybrid Corolla made a clicking noise when starting, sounding like a mechanical watch with gear slippage. Hybrid vehicles are special, and regular diagnostic tools couldn't identify the issue. Later, it was discovered that the contactor in the hybrid control unit had malfunctioned—this component manages the high-voltage power switching. At the time, I waited three days at the dealership for the part, and looking back, it's still quite frightening. My advice is to disconnect the negative terminal and wait five minutes to reset the system after turning off the engine. If the dashboard prompts a check hybrid system warning, do not attempt to start the car again, as high-voltage electricity poses significant risks.

[Renee]

Once in a parking lot, my Corolla wouldn't start no matter what, making a metallic screeching sound ~~ during ignition, with the tachometer needle shaking violently. The mechanic used a borescope and found the timing chain had stretched, causing skipped teeth and ignition phase disorder. The chain cover was even ground into aluminum powder. Nowadays, newer Corolla models have switched to silent chains, reducing such issues, but special attention is needed after 80,000 kilometers. A temporary fix is to pour half a bottle of engine cleaner into the oil filler, let it soak for two hours, then drain the oil. This problem shouldn't be delayed—a friend's car ended up with a dented piston due to skipped teeth.