We have a 2004 RX330 Lexus with 92000 miles. We had the timing belt, tension belt, and water pump replaced last month. When we picked up our car it made a “screeching” sound when started. The mechanic said if it kept it up to bring it back in. It only happens when the car has set for 2-3 days and only on initial start. It sounds like it is coming from the front passenger side of engine.
Sounds like a loose accessory drive belt.
You said, “When we picked up the the car it made a ‘shreeching sound’ when started.”
They should have fixed it then and there. I’m surprised that a Lexus dealer would let this go.
Take your RX300 back to your Lexus dealer and tell them to make it right. You shouldn’t have to listen to belts squealing when you start your vehicle.