Fast, Economical and Accurate method to test for combustion gas leaks from head gasket leaks, cylinder head leaks to engine block leaks. NEW & IMPROVED! Dual-Chamber for Higher Accuracy Test. The tester features a dual-chamber design for higher accuracy to eliminate false readings. The first chamber will filter out any alkaline particles that could result in a false indication of a combustion leak. Test results in the second chamber will provide a true indication of a combustion leak. Works on Gasoline and Diesel engines!