screeching sound
 

I'm wondering why my car is making this thermostat screaming sound, right behind the motor. video - YouTube

Recently put that valve cover on, plugs, cap and rotor.. rpm surges and makes this sound when warm driving and idling, on and off, not relative to rpms.

Was the sound there before the "work"

No it was not.

If the sound is a teeth-grinding screech, the likely culprit is the pax side cooling fan. When fans get old, the motor bushings wobble out of position and the armature hits the stator field magnets. It's not pleasant.

If that's problem, the fix is replacing the cooling fan, usually about $50-$60 for a new fan, motor, and shroud. You can sometimes find just the motor for a few less bucks.

good luck

figured out
 

it was one vacuum hose that was disconnected, not right by where the sound was coming from but next to the cruise control line. reconnecting stopped surge and screeching sound.

All right; THANKS for letting us know. Many times we never hear back.