Will a broken timing belt on 99 Ford Taurus damage the engine?

Yes, a broken timing belt on a 1999 Ford Taurus will almost certainly cause significant damage to the engine. The timing belt synchronizes the rotation of the crankshaft and camshaft(s). When it breaks, the camshaft(s) stop rotating in relation to the crankshaft, leading to:

* Bent valves: The pistons can collide with the open valves, bending or breaking them. This is the most common and expensive type of damage.

* Damaged pistons: The force of the collision can also damage the pistons themselves.

* Damaged cylinder head: The impact can crack or damage the cylinder head.

* Broken connecting rods: The force could also break connecting rods.

Repairing this type of damage can be very costly, often exceeding the value of the vehicle. It's far more economical to replace the timing belt according to the manufacturer's recommended schedule to prevent this catastrophic failure.