What are the reasons for the loud engine noise in the Passat?

[VanSilas]

There are several reasons for the loud engine noise in the Passat, including carbon buildup, poor sound insulation, coolant issues, and shock absorber problems. Carbon buildup: As old engine oil becomes thinner with use, carbon deposits accumulate more and more. Thin oil can easily lead to oil leakage, resulting in increased carbon buildup and significant power loss. When new oil is added, the engine may not adapt to the oil's viscosity immediately, potentially causing higher RPMs and consequently louder engine noise. Sound insulation: If the engine sounds normal from outside but the noise feels excessive inside the car, it indicates poor sound insulation. You should check the vehicle's sealing strips for signs of aging. Alternatively, improving the vehicle's sealing effect and then testing the noise level is recommended. Coolant: When the coolant temperature is too low, problems can arise, and the engine noise may increase. It is advisable to inspect and replace the coolant to prevent other issues. Shock absorber: When the vehicle's shock absorbers malfunction, it can lead to increased engine noise.