dimapb

I have an intermittent sound coming from my engine. It shows up out of nowhere and could last 20 seconds to 2 minutes. Because it's intermittent, I can't seem to pinpoint where it's coming from. Sound file is attached. Hopefully, one of you can recognize it and help me.
It's a 2008 with 79K miles.
Thank you

AustinHusk

Sounds like a water pump? I'm assuming it's that low rattling/knocking sound like boiling water

Rhambler

Any codes showing up? Got me, sounds strange that's for sure. Car drives any different as a result?

1Putt

Could be many things- water pump going bad, bad belts, bad tensioners... take it to a trusted indy shop to diagnose

dimapb

No codes and it drives fine. Water pump was replaced 3 years ago. Didn't think it would go bad this fast. Right now I'm leaning towards the alternator starting to go bad, but will keep an eye on it. This noise being intermittent makes it very difficult to troubleshoot. Thanks for your suggestions.

jmcraney

Maybe it's the Belt Tensioner. Seems like there was a recall or high failure rate in early cars for belt tensioners.

R Z

Take it to Lexus so they can find the culprit to the sound. Depending on what it is and any costs, then you can determine where to get the work done.

Unsober1

I know I am going to get some negative responded to this, but whatever. If you think it's the alternator, have you tried knocking on it with a hammer or heavy wrench. Usually when those go bad, it's the brushes or internal contacts and the vibration of hitting it will cause a change either for the good or bad. Just a crazy low tech test you can try. Years ago I used to always have over powered stereos that would stress the alternator and would frequently has to replace them. Sometime this trick would work.

dimapb

Funny you say this. Last time it was making this noise I had my hood open trying to figure out where it was coming from. Unable to do so, I've decided to drive to the dealer to have them examine the noise. As soon as I slammed my hood, the noise went away.