Well, still having issues with oil consumption and I'm starting to notice smoke....
To preface, those of you who don't know by now, about 8000 miles ago, I completely rebuilt my engine from the ground up trying not to cut any corners.... I think one might be coming back to haunt me though, but more on that after I explain what's going on...
So, I noticed it's using about a quart every two weeks or so of moderate daily driving. First thought was oil leak, but everything is bone dry. At this point, I didn't have any visible smoke. I performed a compression test on all cylinders with my crappy harbor freight compression tester and all of them were really low, like 120, but they were all within less than 5 psi of each other, and I'm pretty sure the compression tester is way off to begin with.
I'm running a catch can, and I'm not catching an unusual amount of oil, and I've tested the system for correct operation.
There are no misfires at all, and I don't feel like power output is down either. Long term fuel trims are within +-2% from 0, and there are absolutely no vacuum or exhaust leaks.
Also, the engine itself is almost completely stock n/a in case someone new is reading this.
Here is what all the spark plugs look like:
basically normal wear and no fouling. So the oil leak must not be that big.
Here's the compression test dry after engine has come up to operating temperature:
And here's the compression test after adding a bit of oil to the cylinder:
What I don't know is whether this is a normal jump in compression for good rings, or whether this indicates an issue with the piston rings.
Here's my hypothesis. Either one or two things are wrong:
1. The only corner I cut rebuilding this engine was using the donor heads from a 142,000 mile grand prix and not replacing or really checking the valve guides, and using cheap valve stem seals.
2. I didn't have a ton of experience rebuilding engines when I did this, so there's a possibility that I didn't gap the rings correctly, but the manufacturer claims they're pre-gaped for this application (sealed power).
What I'm really stumped about is that the cylinders were correctly overbored and honed and new rings and pistons installed, so I don't want to blame the rings. At the same time 142,000 miles isn't that much on the valve guides, so they shouldn't be leaking like that unless maybe the valve stem seals are bad?
Another test I've done is holding my hand over the oil fill neck, and there is no discernible pressure from blowby even with throttle opened.
Did a vacuum test and though it was a tad on the low side of normal, it was still within normal range and it was steady and moved with rpm like it should. Again, if it was rings, wouldn't this be erratic?
Also, the smoke is mainly on startup, and when it's been idling for a while. I don't notice any when throttle is applied. The amount is very slight, but it does smell like oil and it's got a touch of blue grey.
Not thinking headgasket since that's obviously new, and I have no issues with overheating or coolant loss at all currently.
Basically, I'm looking for y'all to help weigh in and help me decide whether I'm looking at another rebuild, or just getting the heads redone. I'm already planning on top-swapping anyhow, just trying to save up first... lol