Why is there a lot of noise when the Sierra cold car starts?

If there is abnormal noise when the engine is started instantly and there is no abnormal noise at idle speed after the engine is started, then this fault point is probably the carbon brush fault inside the starting motor.

The working principle of the starting motor is that the gear of the starting motor is combined with the flywheel of the engine and rotates at the same time through the operation of the electromagnet after electrifying, and then the engine can be driven to start, and the gear will quickly return after the engine starts.

This fault is because the gear of the starting motor does not return quickly, resulting in abnormal sound of the flywheel, so it is necessary to check the starting motor.

In order to reduce the probability of this failure, when you can turn the ignition key to start the vehicle, don't turn the key for more than 5 seconds. After turning the key, let go quickly and let the ignition key return automatically.