Rav4 2007 very loud humming at startup

When I start my 2007 RAV4 6 cylinder SUV, there begins a very loud humming noise that lasts for several minutes. This began happening when the car had about 300 miles on it, it now has about 6,000 miles. It occurs whether the car idles or moves. I read somewhere on the web that it might be a computer controlled startup of systems. It happens on the initial start up every day when I first start the car and even sometimes intermittently throughout the day. I have taken it to the dealer a couple of times, but since it goes off by the time I arrive at the dealership, the techs have never heard it. Furthermore, the repair guys say they have never heard of this complaint and really don’t think I’m hearing anything related to the engine at all. I’m a musician with good ears! The hum is loud and very annoying. Does anyone have experience about this kind of problem and suggestions. I have even considered selling the car rather than live it for the next several years. Thanks. violapicker

There is a high-pressure pump that pressurizes the anti-lock brake system, and it hums, briefly, at startup, but only for a few seconds. I can’t think of anything that would make noise for minutes.

Has the dealer kept the vehicle overnight so they can experience a cold start?

Thanks for your reply…I’ll leave it there overnight and hopefully they’ll hear what I’m hearing. Thanks.