You can do a bush mechanics compression test.
1- disconnect the coil so the engine doesnt fire
2- remove no 1 spark plug
3- place finger tightly over the spark plug hole
4- get a friend to crank the engine with the starter
you should be able to feel the high and low pressure with your finger as the motor turns over. if not then its a problem with head gasket or valves or rings or a hole in the piston.......
good luck