This is a far better way to test and find out where the problems are than a simple compression test.
Note the pistons must be at TDC to perform the test correctly.
AIR coming out of the TB = inlet valve not sealing 100%
AIR ........................exhaust pipe = ex valve..............
AIR ........................dipstick = rings shot
https://www.google.com.au/#q=how+to+do+a+leakdown+test+on+an+engine&safe=off
Note the pistons must be at TDC to perform the test correctly.
AIR coming out of the TB = inlet valve not sealing 100%
AIR ........................exhaust pipe = ex valve..............
AIR ........................dipstick = rings shot
https://www.google.com.au/#q=how+to+do+a+leakdown+test+on+an+engine&safe=off