How do I do a compression check on an engine already removed from the car?

Question

How do I do a compression check on an engine already removed from the car?

Answer 1

John had it right. The best you can do is called a cylinder leak test. The engine has to be TDC with both valves closed. Air is then injected into the cylinder and a second gauge is used to see what percentage of air is being leaked past the cylinder.

You would then listen to see if air is escaping from the exhaust ports (exhaust valves) or from the throttle body (intake valves) or from the oil fill cap (piston rings)

This test won't be terribly accurate as the engine should be warm when doing a cylinder leak test. A cold engine, especially one sitting awhile, is going to leak a considerable amount past the rings.  

Answer 2

Auto technicians can regulate an air supply and connect it to each Cyl at top dead center when the valves are closed and measure the pressure loss. Called a Cyl leakage test and it is much more telling because the engine is cold and you can hear the hissing past the rings and valves.

Answer 3

The only way to do a compression test is to s***w the test gage into a spark plug hole and crank the engine over.

Assuming you have a gage, you will need to secure the engine, supply electricity to the starter, which may not be on the engine but mounted to the transmission, and crank with no fuel or spark.  Make sure the engine is secure.

Answer 4

get a compression tester and follow the directions that came with it,

the quick and dirty method(you still need the compression tester) is to press your thumb onto a sparkplug hole and crank the engine, it should blow your thumb off of the hole. but you should still use a compression tester.