BMW And MINI – Engine Noise At Idle – Chirping
I purchased a 1998 528i 2 1/2 months ago with 164,000 miles. I was told it was maintained very well, including servicing at Motorwerks BMW, (a dealership in the twin cities) oil changes using synthetic oil, and fueling with 92 octane fuel. This is the first BMW we have owned, and my wife and I really enjoy driving it. Recently I began to notice a different sound at certain times. I would describe it as a semi-high pitched rhythmic whine coming from the engine while the car is idling in either D or R. It almost sounds like a quite loud cricket continually chirping. When you step on the accelerator it seems to stop, and if you shift the car into P, it becomes faint enough to almost be difficult to hear. My question is do you feel it is something I should try to alleviate with the products such as Lubro Moly cleaners and protectants, or do you think it is maybe a matter of bringing it to a mechanic to look into having the belts or other equipment replaced. I am not sure if this can be viewed as normal for a vehicle with 164K miles, or if it may be an indicator of something more serious that should be addressed to avoid causing damage. The performance doesn’t appear to be hampered in any way. The car gets good gas mileage, has great pickup especially at highway speeds, and idles smooth.
At this point, we are unable to make a solid suggestion on what the chirping sound may be. Our first thoughts would be the serpentine accessory drive belt and the idler and tensioner pulleys … or …. a vacuum leak in one of the intake or crankcase ventilation boots, bellows or hoses. However, we would suggest some initial diagnostics. Use a mechanic’s stethoscope with a megaphone attachment for locating airborne sounds. While the sound is present, search around the engine compartment (assuming that the sound is coming from under the hood) for the general area of the sound. Then, try to get more detailed. At this point, concentrate on the frontal area where the accessory drive belts and the pulleys are as well as the various air hoses around the intake manifold. Let us know what you find.