I have over 85 K miles on my 98 V6 sedan. A few weeks ago it started
making two noises -- don't know if they are related.

Driving forward, the engine makes a mechanical noise that sounds to me
like scissors opening and closing; sharpening a chef's knife against a
sharpening rod; a steam radiator valve letting off steam
intermittently; or someone shushing, shhh, shhh, shhh. The noise
stops at idle and seems to pick up in rhythm as I drive faster.

Related or not? I hear a high pitched "eeeeeeeeeee" sound when I go
into reverse. Can't pinpoint the location.

Thanks.