My engine was idling strangely (slightly rough and erratic) so I went ahead and did a compression test yesterday. First I did a dry, cold test:
Cyl 1 - 160 psi
Cyl 2 - 270 psi
Cyl 3 - 190 psi
Cyl 4 - 240 psi*
*Note my compression gauge zeroes out at 30 psi so the numbers might not be accurate, but I'm more worried about the differences between cylinders. I added some 5w-30 oil down the spark plug hole and retested Cyl 1 and 3:
Cyl 1 - 240 psi
Cyl 3 - 250 psi
So this indicates bad rings, correct? Here's where I get confused. I also tried a cylinder leakdown test using shop air down the spark plug hole. Cylinder 1 leaks air out the intake at a significant rate, the other three cylinders basically don't leak at all. So this also indicates a bad valve in Cyl #1, right? That would mean a total engine rebuild
Lastly, what really confuses me is that there's no appreciable oil consumption during regular driving and it seems smooth other than at idle, I would have expected obvious oil consumption and blue smoke out the tailpipe with worn rings.
I don't know if it matters but I think the H23A1 uses the FRM cylinder liners. Supposedly this engine was just rebuilt by the PO less than 7,500 miles ago. The valvetrain looked really good and clean when I bought it. It's certainly possible it wasn't rebuilt correctly. Assuming both the head has problems and the rings have problems now I need to decide what to do, I have a lead on a rebuilt head for $200 but not sure what to do about the rings. Might be worth getting a different motor all together.
Cyl 1 - 160 psi
Cyl 2 - 270 psi
Cyl 3 - 190 psi
Cyl 4 - 240 psi*
*Note my compression gauge zeroes out at 30 psi so the numbers might not be accurate, but I'm more worried about the differences between cylinders. I added some 5w-30 oil down the spark plug hole and retested Cyl 1 and 3:
Cyl 1 - 240 psi
Cyl 3 - 250 psi
So this indicates bad rings, correct? Here's where I get confused. I also tried a cylinder leakdown test using shop air down the spark plug hole. Cylinder 1 leaks air out the intake at a significant rate, the other three cylinders basically don't leak at all. So this also indicates a bad valve in Cyl #1, right? That would mean a total engine rebuild
Lastly, what really confuses me is that there's no appreciable oil consumption during regular driving and it seems smooth other than at idle, I would have expected obvious oil consumption and blue smoke out the tailpipe with worn rings.
I don't know if it matters but I think the H23A1 uses the FRM cylinder liners. Supposedly this engine was just rebuilt by the PO less than 7,500 miles ago. The valvetrain looked really good and clean when I bought it. It's certainly possible it wasn't rebuilt correctly. Assuming both the head has problems and the rings have problems now I need to decide what to do, I have a lead on a rebuilt head for $200 but not sure what to do about the rings. Might be worth getting a different motor all together.
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