2005 Honda CRV

I am hearing a whining noise only after car has been running awhile and only when turning left. The noise seems to come from the back passenger side. any ideas as to what this could be?

Bad wheel bearing on right rear wheel.

Honda has a Technical Service Bulletin 07-024 for this problem. It requires that the rear differential fluid be changed and then burnish the clutches in the rear differential.

Tester

“They” say it is a bad rear brake. Need to replace and have rotor filed down. Does this sound appropriate?

It could be a brake problem, sure. The brake pads have a gadget in them that will produce a noise when the pads reach their wear limit. they make the sound to be loud and annoying, so you don’t keep driving and instead get it fixed as it is a safety issue. This usually, on most cars at least, is first noticed when applying the brakes, and not related to turning. Another inde mechanic could take the wheel off and verify the pads are worn and need replacement without much expense. If you are unsure, you could get a second opinion.