why would my 93 saturn motor lock?

Question

there is no spun bearning

Answer 1

Blown head gasket, and the engine hydrolocked.

In automotive terminology, a hydrolock (short for hydraulic lock) is the immobilization of an engine's pistons by a liquid (usually water, hence the prefix "hydro-"). Hydrolocking occurs when liquid fills a cylinder on the intake stroke and, due to the incompressibility of a liquid, makes the compression stroke impossible. This, in turn, prevents the entire engine from turning, and can cause significant engine damage if one attempts to forcibly turn over or start the engine. Typically, connecting rods will be bent, making the engine uneconomical to repair.

It is relatively common when driving through floods, either where the water is above the level of the air intake or the vehicle's speed is excessive, creating a tall bow wave.

Hydrolocking is often a concern when consumers modify their engines with aftermarket intake systems (e.g. Cold air intake). A cold air intake typically locates the filter near the bottom of the engine compartment to gain access to colder air, which can also increase its chances of ingesting water should it be submerged.

Another reason for it to occur is in the event of the head gasket cracking or "blowing", which causes the radiator coolant to mix inside the combustion chamber.

http://en.wikipedia.org/wiki/Hydrolock