Dear Car Talk:
I have a 2016 manual Honda Fit. Sometimes upon ignition, there is a loud whirring noise under the hood that lasts a couple of seconds.
The car runs well, but the noise concerns me. Any thoughts? Thanks. — Alan
I have three thoughts, Alan. The first thought is: When the heck is Season 6 of “Better Call Saul” going to arrive?
My second thought is that you could have a slipping belt. A cold belt that’s worn out will often slip right when you start the car. And then, within a few seconds, the slipping friction heats it up enough so it grabs, and the noise stops.
My third thought — which is the thought I like best — is that you have a bad starter drive. When you turn the key or push the starter button to start the engine, there’s a small gear called the starter drive that shoots out of the starter and engages with a bigger gear — called the ring gear — on the flywheel.
Turning the flywheel is what gets the engine going. Once the engine reaches a certain speed and is running on its own, that starter drive is supposed to retract back into the starter. At that point, the starter’s job is done.
But if your starter drive isn’t retracting right away — if it’s sticky or lazy due to a faulty overriding clutch — it’ll grind against the ring gear after the car starts and make a whirring, gnashing noise.
It can last a few seconds until the drive finally retracts. And, as you can probably imagine, it’s not great for the ring gear, so it’s something that should be fixed.
So my fourth thought — a bonus thought — is that you should take it to a mechanic, Alan. Leave the car with him overnight if need be, so he can hear the noise. A trained mechanic will be able to tell the difference between a bad starter drive and a slippery belt in two seconds. Or as we call it in the business, “two hours of labor.”
Good luck, Alan.
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© 2021 by Ray Magliozzi and Doug Berman