is it 0 compression on all cylinders? it also depends on where ur losing compression at. do a leakdown test. it will tell u where its leaking from. if you hear the air leaking in the intake, then its an intake valve, if its in the exhaust, then an exhaust valve, in the crankcase, then rings or a hole in a piston, or coolant then a head gasket or crack in the head or block. then u can go from there.