Low compression In Cylinder #3

25 percent or 25 pounds? A cylinder leakage test shows the percent of leakage. A compression test shows pounds of pressure.

A compression test just tells you compression is low. A cylinder leakage test will tell you why. That's what you're asking and that's the test you need to do. There are four places to look for escaping air during the test. Hissing at the tail pipe means the exhaust valve is leaking. Hissing at the intake corresponds to a leaking intake valve. If you hear it at the oil cap or dipstick tube, the leakage is past the piston rings. If you see many small small bubbles in the radiator, the head gasket is leaking or the head is cracked.

Leaking on that cylinder-when doing the leakdown-try listening on the exhaust tail pipe, throttle body and oil filler -if you hear air out the exhaust-exhaust valve, out of the throttle body its an intake valve and out of the oil filler -C/rings and cylinder