F5Moab posted this about 18 months ago:
Normal compression for a new engine should be around 215 psi. The lowest reading should not be less than 70 percent of the highest reading. • When the compression measurement is normal, the compression builds up quickly and evenly to the specified compression on each cylinder.
• When the compression is low on the first stroke and tends to build up on the following strokes, but does not reach the normal compression, or if the compression improves considerably with the addition of three squirts of oil, the piston rings may be the cause.
• When the compression is low on the first stroke and does not build up in the following strokes, or the addition of oil does not affect the compression, the valves may be the cause.
• When the compression is low on two adjacent cylinders, or coolant is present in the crankcase, the head gasket may be the cause.
Your leakdown test are very high. Normal cylinder leakage is from 12-18 percent.
• Make a note of any cylinder with more leakage than the other cylinders.
• Any cylinder with 25 percent leakage or more requires service.
•Record the cylinder leakage readings for each cylinder. In excessive leakage situations, inspect for the following conditions:
• Air leakage sounds at the throttle control module or air inlet hose may indicate a worn or burnt intake valve or a broken valve spring.
• Air leakage sounds at the exhaust system tailpipe may indicate a worn or burnt exhaust valve or a broken valve spring.
• Air leakage sounds from the crankcase, oil level indicator tube, or oil fill tube may indicate worn piston rings, a damaged piston, a worn or scored cylinder bore, a damaged engine block or a damaged cylinder head.
• Air bubbles in the cooling system may indicate a damaged cylinder head or a damaged cylinder head gasket.
Will it last another 75K? Could, and could also start burning oil at any time. Need some more testing to determine if it is just problems with the cylinder head.
