Join Date: Dec 2007
Location: Coon Rapids, MN
Car Year: 2008
Car Model: Forester X Premium
99% yes. If it passes the leak down test, the piston rings are good and valves are sealing. If it fails the leak down test he has to check where the air is going, out a valve or past the rings. Fairly easy to do for a mechanic, look and listen.
I use a couple of tricks of my own to help in this. I add a concentrated liquid air freshener for automotive use to the intake air of my air compressor. When I run the leak down test I disconnect the PCV and plug the port on the intake and any others that go from the intake to the crank case. There is always going to be blow by past the rings, thus filling the crank case with the smell of the air freshener and the reason for plugging every thing that goes from the intake to the crank case. Run the leak down test, if the intake valves in a cylinder you will smell the air freshener in the intake, if it the exhaust valves leak you will smell the sent coming out the tail pipe. Stupid simple trick but saves so much time.
I say 99% chance it is good, just because a valve can be tweaked a tiny bit, when the valve closes the head of the valve rests on the seat and can flex the valve stem enough to let the valve to seal and pass a test or even run with out issue. However this flexing will eventually lead to the valve head breaking off the valve stem and destroying that cylinder. The chances of this are slim, generally when a timing belt lets go and valves get bent they get really bent.
His - 08 X Prem 5mt
Hers - 08 X 4EAT