good day

last nite i took my 140 off my patern ship and as i started to turn the crankshaft i heard a hiss from the exhaust outlet ... basicly what is happening is that my valves are not air tight !!! the engine is not rand new ... nore very used ... any suggestiong on what i should do ??? sending it off to servie is not an option becaue i am not in the us ...

thank you