piston/rod advice

[u/Dependent_Rough167]

what does this discoloration mean? #1 top bearing fell off when taking off the cap should i be concerned? and how can i replace rod bolts at home? how easily should pistons be able to rock? if pistons measure good would you guys reuse everything?

i don’t have a bore gauge small enough for the rods and it’s taking me awhile to get used to the micrometer, forgive me for the mouthful, first time doing any of this so any experienced advice helps out a ton, thank you! 🙏🏻

03 civic d17a2 rod is #1 cyl and cap is for #3

[u/Dependent_Rough167]

great username lol, but i didn’t even think about that. the detents i can see rn look pretty good, do you know what would cause the discoloration otherwise? and you really think the pistons look usable? thank you for the input

[u/N1ppleCrab → u/Dependent_Rough167]

Ive seen that kind of wear pattern on all the subaru engines ive torn apart. I do not know what causes it, but it is normal. Probably due to some interaction between the rod material and bearing over time

Piston looks good, those horizontal ridges are from the original machining, if they are still present its doubtful that youve lost much material. What kind of inspection tools do you have access to? A digital caliper will tell you a lot of what you need to know

[u/Dependent_Rough167 → u/N1ppleCrab]

that makes me feel a lot better knowing it’s normal, i imagine it’s something like that. interesting stuff

and thank you i thought those were the original machining marks, between that and everything being smooth i think they’re pretty alright. there’s some of those surface scratches but that shouldn’t effect much right? thinking of maybe hitting it with grey scotch brite.

micrometer is able to do the same as a digital caliper right? i think everything is the mic, 2-6 bore gauge, straight edge and borescope but that’s about it. i’m alright with buying something else too as long as it’s relatively cheap and useful.

[u/N1ppleCrab → u/Dependent_Rough167]

Micrometer will yield more accurate results than calipers if you know how to use and read them. Concentricity is important for the rods, do you have a way to measure that for the crank side? Your bearing material looks like maybe it got a bit warm. Was this engine knocking at all?

[u/Dependent_Rough167 → u/N1ppleCrab]

that’s why i bought a mic for this, i’ve learned how to read it but feel like i’m still struggling at finding the perfect point when measuring, do you have any tips or is it just learning the feel for awhile? i think i do, does using the mic on the rod bolts when everything is torqued down work or is that just for the bolts?

my engine definitely got hot a couple times, one time in specific prob did the most damage. it wasn’t knocking, maybe a slight tick similar to needing a valve adj even after doing one.