Damn... I haven't seen many cracked pistons but I expected you would've been able to see it from the top. I guess the skirt is weaker?

Quick work! Giving @Z_WAAAAAZ a run for his money :bowrofl:

Any thoughts on the next steps? Throw another stock piston in and pull some timing? I think there were some used forged pistons in the classifieds on here not too long ago.

Im surgical with it, the issue is i never went to college.
any ideas why the cyl2 plug and faces are vastly different? Can i not trust my injectors?

Didnt even make bad noises either. I was pretty slow with it because I wasnt excited for what i was going to find, now im not too torn up except that i have to reclean things. The bearings look… ill post photos.
current plan is getting some stockies and following the rules of the ancestors, and my peers. Spicy timing is spicy. Sourcing used forged pistons without boreing is hard it seems. Thinking ill grab some headstuds, using the stocks a 5th time is rough, also some new rings for everything. Its easy to eliminate scope creep when the car has taken all of your money. It does need a clutch too…

Jeeze, dude doesn't take a break. Quick work. Also just saw the spark table in the other thread, which explains all of this. And Simba guessing the cracked piston, wow what a wild ride! Hope you get it back together soon!

These bearings look real rough for 600 miles, the issue is wether or not its because of the metal in the oil after cracking the piston, or i had some crazy wear. Either way i think I should replace. Do we think mains are just as bad?
https://cimg9.ibsrv.net/gimg/www.mia...3df4a5b9c.jpeg
https://cimg0.ibsrv.net/gimg/www.mia...4c8d07984.jpeg
https://cimg1.ibsrv.net/gimg/www.mia...1b000faab.jpeg
https://cimg2.ibsrv.net/gimg/www.mia...a67deaee4.jpeg
https://cimg3.ibsrv.net/gimg/www.mia...0d65705d4.jpegAnd i suppose another lesson learned, speedrunning these expensive lessons. A cool cracked piston to put on my bent rod, yippee!

Those bearings don't look great, but new bearings do typically have a coating that wears off pretty quickly and can look bad even though it's normal. Hard to tell in the pics. Can you catch a nail on those scuffs? Either way bearings are cheap in the scheme of things and I'd go with new ones and flush the oil passages to be safe

thought i replied guess it didnt go through. I took out the mains to check them. Given the acl rod bearings had copper showing already i figured it would be best if i did the whole shabang again. I found acl race bearings for 15$ on scamazon last time i did this and just reordered those. It looked like the base timing was off, but i couldnt be sure, going to get new covers and check everything when its all said and done. I can catch my nail on rod bearings, and mains look better but still slightly feel with my nail.
https://cimg3.ibsrv.net/gimg/www.mia...b64f89465.jpeg
https://cimg4.ibsrv.net/gimg/www.mia...0eae3fbb1.jpeg
https://cimg5.ibsrv.net/gimg/www.mia...d837d38fc.jpeg

can you share the spicy spark table here? keen to see how spicy is spicy :)

In the meantime whilst i wait for parts (and money) i took on a clutch and front reseal job for a local group member. I had put in a new master and slave cylinder because they had a warranty, and the car stopped going into gear. was textbook hydraulic symptoms. Did those and nothing changed. This is a 97 m edition that had the cleanest stock underbody id ever seen about a year ago. Didnt leak a drop of anything. Its started to show its age.
https://cimg3.ibsrv.net/gimg/www.mia...905c355b6.jpeg
https://cimg4.ibsrv.net/gimg/www.mia...49c5c35cc.jpeg
Found my smoking gun after the trans got ripped out.
https://cimg6.ibsrv.net/gimg/www.mia...f5a77e2c1.jpeg
And the noise she didnt tell anyone about
https://cimg7.ibsrv.net/gimg/www.mia...c0a3585b3.jpeg


tired of mechanical work but 300$ for a clutch job and reseal is gonna help pay for my own rebuild. Though im pretty sore, i should have charged more 😅

https://cimg1.ibsrv.net/gimg/www.mia...1bae591ed2.png

embarrassing but you live and learn

Haven't had a chance to post before because of my own motor shenanigans, but I've been following. Bummer that you had this failure, but you're certainly giving Zak a run for his money with how quickly you get after it. Big props for that. Godspeed on getting it back together.

Well, got the crank as polished as i could, and cleaned out the oiling holes with a lot of brake clean. The amount of gunk that came out is insane. Fresh clean table and cloths ended with this.
https://cimg4.ibsrv.net/gimg/www.mia...4914cd118.jpeg

as for the bearing surfaces, im not happy with or confident with them at all. There are a few grooves i can catch my nail on after polishing. The worst being on the furthest main journal surface.
https://cimg1.ibsrv.net/gimg/www.mia...d4711be33.jpeg
https://cimg0.ibsrv.net/gimg/www.mia...c7ec9855e.jpeg
That line on the right is the issue

im going to go ahead and call around for some quotes on crank polishing. If they cant polish it out decent enough, i have another crank i can buy and polish that I think is an option.

ive always heard a valley is fine and just holds extra oil but the high spots hurt things. Not sure if this tracks here but still not confidence inspiring

Think im going to try and polish that line out a bit more later. in the meantime, I glanced at the thrust bearings i reused and were in spec the first time i built the motor. There is a ton of wear that wasnt present and they look horrible. All to say that I cannot find any thrust washers for the vvt specific size for under 40 mf dollars. Anyone have a source or vendor that sells them? I had planned on replacing them the first time but the ones i bought off rockauto were for the earlier years regardless of what it said.

Well everything was coming together, was going to be able to have the car running driving tuesday. Went to put the new/used oem pistons in and they wont fit. I used them to push the rings down and measure them, so the crown fits, but the skirts are too wide. My stock pistons fit in and out easily. My skirts measured about 82.5mm vs the used ones being 83 and some change. Guess ill source pistons and wait on those. Bummer, im running dry on this money aspect atp
https://cimg5.ibsrv.net/gimg/www.mia...aa9d23519.jpeg

This is weird... Did you accidentally buy some stock style 83mm +.5mm overbore pistons? Stock bore is 83mm so if these check out at .5mm bigger than yours I feel like this must be the case. Also, you have some sympathy from me in the wallet department. I'm building a bottom end for mine (just doing it before I ever blow mine up in the first place) and it is indeed expensive AF every step of the way especially if you involve a machine shop...

They were used "oem" pistons from a local friends n/a build he did on his na, he used vvt pistons and some other stuff. Im guessing he just had a block that was overbored slightly with some cast pistons in the right size for it, and didnt know they were slightly oversized. I have another set now, just waiting to have some time off to get it done. I got myself burnt out a little doing a ton of things at once.

Yeah I feel that man. I get a little overwhelmed when I look at my boxes full of parts that I'm trying to get installed over the winter, plus building an engine, plus wiring in new sensors. Good luck with your engine overhaul I hope it runs well after!

I got lazy, but the car has been together, ive done about 50 miles, first 5 breaking things in , rev high, coast down. Wastegate wired open, and low boost after. Ive changed the oil once after about 3 miles to get whatever gunk was left in there out, and the ring and other materials out. Going to change it again later today before i drive it. I noticed on the low boost small pulls i did, i was pushing a good amount of oil out of the valve cover breather. I hadnt connected my catch can on that side and let it vent to atmosphere. When the vc was off, i drilled out that hole and the hole inside the baffles to let it flow a bit more.

for shits and giggles after about 50 miles i ended up doing a comp test. This motor has been rebuilt twice so far with only honing, no boreing, had 250k miles when i did that, and had me as a builder, so i didnt have the highest hopes. This time around i ended up using a flat stone hone to rid the bores of high spots/low spots, then gave it a small once over with the brush hone.

i noticed there was a good amount of oil in cyl3, sitting on top of the piston. This was obviously ideal, and i didnt have anything pointing towards the valve cover leaking.

The comp tests were about 150 each cylinder hot, give or take 5. This isnt “new engine” rebuild numbers, but for a tired motor im fine with it.

i file fit the rings both times around, this time leaving a larger gap (slightly larger than i wanted on some) just in case the last piston cracked due to ring gap issues.

https://cimg5.ibsrv.net/gimg/www.mia...0564034e8.jpeg

3 obviously had larger compression ring gaps, but i ended up measuring the oil control rings at about 0.014 iirc. Ofc i didnt write them down… there are some marks in the bore, they dont look too good, or too bad…

https://cimg3.ibsrv.net/gimg/www.mia...806cf1df2.jpeg
This is the oil left after letting it sit overnight

this is nothing but a product of my own, so im only really bummed because I hadnt taken more data down. i havent seen any huge plumes of smoke yet. The plan the first time around was to get this done quick and dirty, and gather big boy parts like forged pistons, boundary pump, genuine good parts +machining money, to get it done right. Whilst this works (or doesnt ^^^) for getting the car up and going. I genuinely hate breaking in and driving a motor i built haphazardly. Im not saying this wont run fine, burn oil, and rip, and im going to find out if it does just that.

now to the clearances. Big ol dumb me had the measurements i took last time in my phone, but still ordered one std size rod bearing pack. I measured all the rod journals at around 0.015” which is on the tight/middle end of the oem spec iirc, not where id like to be, but it runs. Had i used my brain, i would have gotten an undersized set and used a half std half undersized combo to get what id like to be at.

my mains werent bad from what i had seen.

https://cimg0.ibsrv.net/gimg/www.mia...d9e05b7e1.jpeg

Whenever i get done with dyno oil, i like to run 20w50 vr1, keeps my oil pressure up, and global warming and texas makes sure i dont ever have super cold conditions. This also helps with oil not getting past the rings so ive heard.

Im not sure if thats a good update or a bad. Im going to beat it up, see what happens, and persnaps just end up emptying catch cans before i drive everywhere.

for now im just glad to have my car back, and my garage clean again.
https://cimg0.ibsrv.net/gimg/www.mia...4b24601d6.jpeg

Getting the garage cleaned up after a massive job like that is the most cathartic thing to me. Easy to worry on a fresh rebuild. Get some miles on it and see what the real issues are.

Oh yeah, and change your spark map this time :bigtu:

Props for getting it together. That oil ON the piston sure looks like it got in there after shutting it off. It's way too clean to look like blowby to me, plus that doesn't usually end up on top of the piston after you shut it off. That looks like a valve stem seal leak to me. Boroscope might tell you if that's the case. But really I'd just send it and see how much it uses. They all use SOME oil.

Compression numbers, those check out as well. The aboslute numbers always vary, the spread is the important part. The blowby/catch can might be a bad sign, but you still need to break that thing in. Also looser gaps always mean more blowby. Mine has a bit and I had to increase crankcase ventillation which fixed my catch can filling issue. What's your PCV or catch can setup look like?

ended up copying your spark map, minus 3 in the meaningful areas, im going to do some drives and listen with my knock setup to see how things fare :) though with the oil in the cylinders im not sure if i should retard it a bit more

stem seal is a 100% leaking item, i didnt check them, but given the insane blowby i had when i cracked the piston, i had oil coming from every fresh seal, i guess not impossible it pushed some seals off? Who knows, an easy check. Even easier to check since ive developed a huge oil leak from the little plastic plug on the back of the head, where the earlier cas would be. Anyone know how to seal that up? I have one catch can inline with a msm pcv valve, and one on the valve cover venting to atmosphere.

i did spill some oil in the plug valley that definitely seeped into the not sealed plug well, so i imagine thats where my oil came from. -- edit: forgot they have slight steps, so this isnt what happened, just pissy stem seals ig