Whenever strange metallic noises start coming from the engine compartment, you must take action. Let's explore the potential dangers of engine noises in a BMW.
Question from a BMW driver
I want to know why my car loudly «pops.» When the engine is cold, right after starting, you hear a loud crackling for 2-3 seconds, which immediately stops. Then everything is fine. It runs beautifully, smoothly, and quietly. This rarely happens with a warm engine.
The car has an original mileage of 122,000 km. The effect is similar to starting a diesel at 30 degrees below zero. Three seconds of loud operation and then normal. I wonder if this is due to some minimal leaks in the oil circulation system, because it began to slowly leak from the solenoids, shaft sensors, and the base of the filter. A colleague said that the cause could be a valve at the base of the filter or a timing chain tensioner, but this is not certain.
Response
Sounds that persist for several seconds after starting a gasoline engine usually originate from the synchronization area. A cold engine after a longer period of inactivity may not have the necessary amount of oil in the upper part, and thus, components that depend on its proper quantity can cause operational noises.
Want to know more about your car? Read our other tips on caring for your BMW.
First and foremost, these are the hydraulic valve lash adjusters, Vanos control units, and timing chain tensioners. Modern engine oils have corresponding additives that cause a slower oil drain into the oil pan after the engine stops and oil residues in the upper part. For this reason, it is crucial to use oil of proper quality in accordance with BMW recommendations and to change the oil and filter no later than the period indicated by the vehicle's information system.
Similar symptoms with sounds during engine startup also occur when the timing chain or chain tensioner is not functioning properly.
