Hi. Yesterday when driving my 2006 Volvo S60 (turbo) down hill, I felt a light pop and felt the car yank slightly to the right (passenger side). It was very slight. I pulled over and didn't see anything so I continued and noticed that there is a mechanical or spray or buzz or fan-like noise that I can hear coming from the passenger side (under the hood) when pushing the gas pedal. No warning lights have come on.

Does anyone have any ideas on what I should check? It has about 120K miles.

Also, I noticed many times that it takes a smidge longer to turn over at start. I also noticed that RPM guage jumps twice very quickly sometimes at start. Not sure why and only sometimes.

Thanks for reading!
Ali