9 times out of 10, if a head gasket is blown.....
compression is diminished to the point that the fuel mixture wont ignite. If it will start, youll hear a faint to loud "whistle" or "swish".
Easy way to check for a broken conn rod or wrist pin is to.....
Take a metal coat hanger and unravel it. Put a bend in it (curve). Take out the spark plug and insert the wire in the hole until you feel the top of the piston. Now, turn the engine over slowly by hand. If the wire does not move in or out......the rod is broke.
Most times if it is broken near the piston, the engine will not turn over due to the rod being stuck on something inside the block.
Hope this helps.
COTLOD, October 2009