Vehicle condition: 2019 Mercedes-Benz GLC, engine model 274 920, more than 41,000 kilometers driven in 2 years, no accidents.
Fault description: When the cold car starts, the engine has a metal friction sound.
The metal sound of the Mercedes-Benz GLC cold car starting may be caused by these reasons: 1, insufficient oil; 2, the starter engine failure; 3, timing chain tensioner failure.
Fault cause 1: insufficient oil.
When the cold car starts, the oil is still in the oil pan, and the oil pump does not immediately deliver the oil to the inside of the engine. At this time, the engine is not working smoothly due to the lack of oil, and the internal parts are not working smoothly, and there is a situation of abnormal noise, which is a normal phenomenon.
If there will be abnormal noises and shaking after the hot car, it may be that the oil is insufficient. Then, the owner can check the oil level by himself to determine whether the amount of oil is sufficient.
Solution 1: Add oil, the car oil specification is 5W-40, the cost of the 4S shop is about 300-500 yuan / L, the cost of the repair shop is about 100-300 yuan / L, the owner needs to pay himself.
Fault cause 2: Starter failure.
The maintenance technician first unplugs the positive electrode of the power supply, removes the starter, and observes whether the drive gear of the starter is dropped or deformed, and the fault can be confirmed. If the drive gear of the starter fails, the car will have a metallic friction sound when it starts.
Solution 2: Replace the starter and the 4S shop is free during the warranty period. If you are out of insurance, the replacement cost of the 4S shop is about 10,000-15,000 yuan, and the replacement cost of the maintenance shop is about 8,000-10,000 yuan.
Fault cause 3: Timing chain tensioner failure.
The maintenance technician opens the engine hood, removes the timing side cover, removes the timing chain tensioner, and presses the tensioner by hand to see if it can be returned to normal position, and the fault can be confirmed. If the timing chain tensioner fails, it will cause the timing chain to work abnormally, and then there will be abnormal noise.
Solution 3: Replace the timing chain tensioner and replace it free of charge at the 4S shop during the warranty period. If you are out of insurance, the replacement cost of the 4S shop is about 1000-1500 yuan, and the replacement cost of the repair shop is about 800-1000 yuan.
Summary: After testing, the car in the case is due to the abnormal noise caused by the fault of the starter drive gear, and the specific treatment method can refer to Solution 2. In this regard, we recommend that car owners maintain their cars regularly and check the oil level regularly.