Great idea, I'll try to find some time to do that tomorrow.

Did a leak down test today. Results were 4% 9% 5% and 6%. Im gonna go ahead and do valve seals tomorrow.

That's not that great... where was it leaking for each of those? Rings?

I would say those results are pretty good and a big relief. All losses were past the rings. According to every piece of literature out there anything under 10% is considered excellent condition. Keep in mind, ring gaps are set relatively loose on this car as they should be so some blow by is expected.

I would be ecstatic with those numbers. A leak down doesn't tell you oil control ring condition though.

I would be leaning toward stem seals though.

Well good for three of them but 9% I would expect out of like a 125k mile street car.

Oil is in all of them though so seems like not related. Hoping it's the valve seals.

Changed the valve seals today, used the oem kia ones. Seems better but could be placebo, also needs some time to burn out the residue. Will know after I drive it to work tomorrow if it used any oil.

Anything appear wrong with the ones you took out?

6
Didnt fully inspect them but the ones I looked at seemed pretty normal.

So it's no better. Used a qt of oil on my way to work, it's weird because it doesn't even smoke much. Pulled the plugs, still a pool of oil on the pistons. I'm honestly done, I'm not gonna sell the car but I'm gonna put it away till the winter when I have time to do another rebuild. Pretty much gotta be the oil control rings at this point,

When you rebuilt the engine, how much was the oversize on the pistons? What brand pistons and rings? Did the machine shop assemble the bottom end? What were the tolerances?

83.50mm Arias pistons using the Arias supplied rings. I gave the pistons to machine shop for measurement but I assembled the bottom end. Not sure what p2w measurement he went with. I don't recall but I believe I set the gaps to 0.021. I should know better but I'm second guessing everything now and wondering if I installed the scraper rings all upside down. I obviously make the same mistake on all 4 cylinders whatever it was. I have a lift in the garage and a cherry picker so it isn't the end of the world to pull it apart, I'm just tired of working on it although my wife is insisting I should just fix it. I was gonna swap in my 6 speed soon anyway so I guess pulling the engine is ok. I'm honestly just glad I'm not gonna have to pull the oil pump, crank, water pump ect.. just checking and replacing the rings isn't nearly as much work as the full rebuild.

https://cimg7.ibsrv.net/gimg/www.mia...c5bbf7b9d9.jpg

What the fucking oil control ring gaps... How did i miss that? Well i guess im an idiot.

Looks like 0.21 on the money.

Pretty close. Maybe 0.40 even. Upper 2 rings were on the money, just the oil control rings were all kinds of fucked.

Some bad pitting from detonation, i assume from the excess oil. You can see how much oil was sitting in the cylinders at all times.

https://cimg2.ibsrv.net/gimg/www.mia...e6dc14cbcd.jpg

https://cimg7.ibsrv.net/gimg/www.mia...6ad3759ad2.jpg

Whoops. That sucks man...

Ya, it's shitty but it would be worse if I didnt see an obvious problem. So that's good lol. Good time to swap in the 6 speed too.

like so many rebuilds, things go wrong...

"fuc this thing, im selling it"


two days later.."ok so I took it apart and found this".


I live by this strategy.

Lol I told my father in law last night the miata is done for the year and Im burnt out. 2 hours later I had found the problem and ordered the parts. Haha there is no way I could let it sit for a year, I am too obsessive for that.

Look at Arias end gap recommendations for oil ring: 0.20" per inch of bore... Guess it was in spec :p

https://cimg0.ibsrv.net/gimg/www.mia...0ddaf128f1.jpg