Hi everyone, The engine of my 2006 prius started doing some weird noise recently. It has a high frequency clicking sound. It's fairly loud. The sound disappears when on electric mode. There is no engine light on the dashboard. The oil was a little low so I added more and it still does the sound. I changed the coolant flow control valve recently, I am not sure if it's related. Would you be able to help diagnose this issue? Thank you for your help!
might be noisy tappets from the low oil situation. how many miles on her? can you post a recording of the sound?
By "high frequency" do you mean the pitch of the clicks (like a sound above 4000 Hz) or that the rate is fast and the clicks are just, well, clicks.
Thank you for your responses! Here is a video of the of it with the sound: https://youtube.com/shorts/5x6Xoerk5cM?feature=share
That's a very regular click that I would take to be mechanical, and it seems to be around ten a second, or around 600 a minute, or around half the crank RPM, so in the valve train. Excessive clearance between rocker and tappet at one valve maybe? Bad spring or sticking valve? Might not be too hard to spot with the valve cover off.
