I was browsing Amazon in search for a combustion leak detector (AKA "block tester") and I stumbled upon a cylinder leakage tester kit, which is supposed to do similar things? But I am not quite sure how it works? I see it comes with valve nozzles but that is it. How do you connect it and to which parts of the engine in order to do the testing?
A cylinder leak-down tester is a completely different animal than a combustion leak detection kit and has a completely different job. While the combustion leak detector checks for carbon-dioxide (CO₂) in the radiator. The cylinder leak-down tester kit hooks up to to your cylinder through the spark plug hole on one end and to your compressor on the other. You pressurize the cylinder and leave it for a period of time mainly to check the seal on the valves. Something like this would be used after an interference motor has lost a timing belt to see if any of the valves are bent (it has other uses as well). You wouldn't normally use it to check for a blown head gasket.