I've got a '99 sportage I'm looking at with the 16 valve 2.0 (FE3 Mazda, I believe) engine. Getting a misfire code on cyl #4 and engine is running rough. I checked (dry) compression on that cyl (which is the one closest to firewall) and pressure was around 40psi (the others are around 180). I pumped about 40psi compressed air into that cyl via spark plug hole (made sure all valves were closed and put breaker bar on crank pulley to keep piston from moving) and I can hear air escaping around the hole itself and also out of cylinder #3 hole. I conversely also pumped air into cyl 3, but curiously didn't hear air out of 4. In either test I saw no bubbles in radiator.
Does this sound like a head gasket? Owner says there's no history of overheating.
In case anyone's wondering, I don't think the leakage I descibed coming from cyl 4 hole when I tested 4 is coming from the tester not sealing properly. The threads on the head feels fine and the plug seat looks visually OK. Also,.when I used the tester on #3, there was no leakage there (I also used tester on cyl 2, just to double check, and no leakage from there either),