1. The starter motor is engaged. This is the most common cause of this noise. When you turn the key in the ignition, the starter motor engages with the flywheel and turns the engine over. If the starter motor stays engaged after the engine has started, it will make a grinding noise.
2. The timing belt is loose or damaged. The timing belt is a critical component of the engine that synchronizes the movement of the pistons and valves. If the timing belt is loose or damaged, it can cause the engine to make a knocking noise when you try to start it.
3. The fuel injectors are leaking. The fuel injectors spray fuel into the cylinders of the engine. If the fuel injectors are leaking, they can cause the engine to flood and make a gurgling noise when you try to start it.
4. The spark plugs are worn out or damaged. The spark plugs ignite the fuel in the cylinders of the engine. If the spark plugs are worn out or damaged, they can cause the engine to misfire and make a popping noise when you try to start it.
If you are not sure what the cause of the noise is, it is best to take your car to a mechanic for diagnosis.
