The is a squeaking noise coming from the engine, it sounds like it's a from something rotating. The frequency of the noise increases with the engine rpm.
A warning light that looks like the one pictured on this page has appeared on the dashboard and doesn't go out after the car has been running for a while.
The engine temperature warning light shown in the picture (or one very similar depending on the car manufacturer) has appeared on the dashboard and stays on.
The steering is suddenly a lot heavier than it used to be. It's now very difficult to turn the steering wheel at slower speeds.