Just did a compression test and now I'm confused

[masospaghetti]

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.

[thumping_accord]

How did the PO rebuild the motor? Did he just replace all the gaskets and bearing and put the original pistons, valves, springs, etc... back in? or did he do a complete rebuild with new valve, pistons, etc...? Also can you notice any "extra" crank case pressure (is your oil dipstick popping out, or oil coming out of areas it shouldn't be like the alternator or in the intake)? Just because the air leaks out cyl#1 it could be related to the piston or valves. Try finding someone with a borescope you can borrow and inspect the valves.

When I built my H23A1 I did not pay special attention to the sleeves and wound up with a cracked piston, but my crank case pressure was through the roof, ie my oil would shoot out my dipstick tube lol. I never did a compression or leak down prior to that happening though.

[masospaghetti]

Not sure what was involved in the rebuild. He said he put in H22A 12.6 C/R pistons but I don't know what machining work was done.

Doesn't appear to be excessive crankcase pressure, I can feel some coming out of the oil filler hole but not a lot.

[masospaghetti]

I took the valve cover off to inspect the valves. One of the intake valves for cylinder 1 had zero lash - The valve was never closing! Here's the weird part. I loosened the adjuster as far as it would go and the valve lash is still too tight, although I was able to get just a tiny bit of play in there so the valve hopefully will actually close now.

Looking at the intake valves side by side it's apparent that the uncompressed height is taller than the one next to it. Maybe the PO installed the wrong valve spring?

I still have a coolant leak to fix from my oil cooler but assuming the engine runs OK i'm planning on just running it as is.

[Fleetw00d]

I took the valve cover off to inspect the valves. One of the intake valves for cylinder 1 had zero lash - The valve was never closing! Here's the weird part. I loosened the adjuster as far as it would go and the valve lash is still too tight, although I was able to get just a tiny bit of play in there so the valve hopefully will actually close now.

Looking at the intake valves side by side it's apparent that the uncompressed height is taller than the one next to it. Maybe the PO installed the wrong valve spring?

I still have a coolant leak to fix from my oil cooler but assuming the engine runs OK i'm planning on just running it as is.

Possibly an incorrect valve (longer) was installed; check to see if one of your exhaust valves is too short.

Coolant leak at the oil cooler is probably one of the hoses.

[masospaghetti]

Although not ideal, am I risking anything by possibly running the wrong valve in there?

Other than the valve lash being off?

You're right about the coolant leak, Fleetwood. What an awful place to try and work to replace the hoses.

[Grumpys93]

Since I had something similar, not being able to adjust the valve lash on my f22b, I found that the shop I took it to previously jacked up the valve seats and ground them down too far. This made the valve sink in and making it impossible to adjust the valves. Just another idea of what could be going wrong.

[dbsharp]

I'd pull the head and inspect. Check for valve guide wear and valve seat contact. Guides can be worn out pretty bad without seals leaking oil.

[deevergote]

If you pull the head, definitely inspect the cylinder walls, especially in 1 and 3. FRM is great stuff, but it is pretty unforgiving. If it was damaged in any way, it may be preventing the piston rings from sealing correctly. check very carefully as far down as you can for any sign of damage. Rebuilding engines with FRM sleeves can be tricky. I know a few pros that won't do it. An amateur could easily have missed a problem... or caused one.

[masospaghetti]

My bet is the valve seat was machined too much / incorrectly. I looked the valve specs and the intake valves are longer than the exhaust valves so IMO its less likely the wrong valve is in there. (If the exhaust valve was installed there it would be too short, not too long).

I'll plan on getting that spare head and gaskets on hand, probably go with a cam upgrade at the same time (and maybe actually a real header) and run the current head in the meantime.

On the plus side the idle problem has gone away and the engine is running really nice now