When a car engine become weak and looses power due to age or any other failing reason, it is the best to go for engine compression test to mechanically diagnose the true status of engine health. A compression test is used to determine the condition of components inside the engine cylinder such as head gasket, piston rings, valves and valve seats.  This is a very simple test and something you can do it at home even, interpreting the results is a different matter and something we will discuss