I have a 99 Toyota Corolla with 255k miles. According to the service manual, cylinder compression should be 145-218 psi, with no more than 15 psi variation between cylinders. I tested mine and read 30 psi variation before adding oil for a wet test. After adding oil, compression was a bit high. The compression slowly built up after 5-10 engine strokes.
|Cyl.| Dry | Wet | ------------------ | 1 | 190 | 210 | | 2 | 180 | 210 | | 3 | 200 | 230 | | 4 | 210 | 220 |
From what I've read, the slow pressure build-up, plus the higher pressure after adding oil, indicate worn piston rings. As I don't have low compression, I don't see evidence of a bad head gasket.
What do these numbers tell me about the engine condition and/or expected time until rebuild?
Note: The car has been burning oil for a few years, and has smoky exhaust. I assume oil slipping by the piston rings is a contributing factor. Also, oil has been collecting in one of the spark plug wells.