2006 Ford Fusion Car problem

The problem is no one ever taught you to stop the engine, not drive it until it was destroyed. At this point repairs are most likely not the best solution. No engine is meant to maintain 6000 rpm. That alone can be considered abuse. When the serpentine belt came off, the power steering pump, generator, and water pump stopped working, so you lost power steering assist. That was the first clue there was a problem. The generator stopped recharging the battery so those warning lights came on. That was the second warning. The car can still run on just the battery for about a half hour, but then it will stall. Everything was still on just like it is before you start the engine because the battery wasn't totally dead yet. With the water pump not working, of course the engine is going to overheat within a few minutes, but by 20 minutes serious damage was done. You would have seen steam coming from around the hood, there would be no heat from the heater, and there would have been a warning on the dash from a light or temperature gauge.

At this point you can try to refill the coolant, replace the belt, charge the battery if it's too run-down to crank the engine, then try to start the engine. There will be one of two possible outcomes. There's a 95 percent chance the engine will have a warped and leaking cylinder head and gasket and if the engine runs, you'll see white smoke from the tail pipe. That's from burning coolant. There's a 5 percent chance the engine will run fine with no symptoms, but there will be problems soon. The temper will have been lost from the piston rings leading to early failure and burning oil, and the oil will have broken down from the excessive heat and lost it lubricating qualities. That will quickly cause wear to the engine bearings. Once one bearing starts to tear apart, total failure takes just a few minutes. That will result in a loud banging or hammering sound.

The most economical solution at this point is most likely a used engine from a salvage yard. The good news is at the mileage you listed, you already got the biggest percentage of life out of your engine.

If it's running now and the belt has been replaced, drive it for a while before thinking about replacing the engine. You might get lucky. If it does come to that, the cost of an engine depends on how many miles it has on it, how many of them are in the salvage yards, and how much that model is in demand. Your local repair shop will be able to give you a better answer. They might also determine repairs are a better value than replacement.