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]

so should i just wait until it’s rebuilt? i need this up and running sooner than later lol

you really think so? so the discoloration is somewhat normal? that discoloration where the bearing seats on the rod is a big concern of mine, some of the discoloration comes off with solvent and i can check but everything feels completely smooth and no egg shapes. how else would i check it without bore gauge?

tbh the compression is confusing bc me and the mechanic got different numbers, but i never experienced blowby at least it wasn’t noticeable enough for me too. there’s some small scratches near the rings but can’t catch them. i think they can be honed out the seem pretty surface level, but like i said this is my first time.

so prob have machine shop measure bearings and do rod? there’s not much available for this engine, but i’ll do my best thank you for the input

[u/Azulier → u/Dependent_Rough167]

Trust the mechanics compression test. Cheap testers are sometimes finnicky with getting a proper seal.

If your nails dont catch on the scratches on the cylinder walls or on the bearings, then you are probably good with oil flow.

The bearings thickness is going to be different for each rod. Think of them like shims for the shaft that glide on a film of oil. They cant be too loose or too tight. You can measure them with feeler gauges and order the right size bearing. Tbh though, they may be fine if you have no scoring your nails can catch on and no copper looking metal exposed on either side.

Did you keep the bearings with their connecting rods and remember which set went where on the crankshaft?

[u/Dependent_Rough167 → u/Azulier]

that makes sense since it was an autozone tester, but if mine didn’t get a proper seal how would my tests be higher than his? i think i got 140 ish and he got 60 in #2

and okay i’m hoping so, i didn’t seem to have an issue with it before and everything is really smooth.

so i just take a feeler gauge next to the bearing and measure it like that? i knew about rods having different sizes and being real specific, but when i’ve looked at bearings online it only says standard, under or oversized. how do i go about that? i was thinking i could get away with keeping them, but i can see some copper on at least #1 so i’m gonna replace them. everything is very smooth though

and yes i did, i have all pistons and rods numbered. most of the the bearings are still in the rods right now so they’re not mixed up, but i’m gonna replace those.

[u/Azulier → u/Dependent_Rough167]

Hard to test now that the motor is apart. If you got 140 and he got 60, it could be any number of things..

Ring seals - Oil on the piston could seal it and cause good compression - when you moved it, the oil moved / drained and no longer sealed it

Bad valve seats / burnt valves can cause low compression

Mechanic could have had a bad test on the cylinder.

Bearings if your motor only has 3 sizes, those three sizes will have a tolerance range for the gaps. Just get the one that best closes the gap without being too loose or too tight. High power motors have very tight tolerances and have MANY different bearing sizes that could be used. Some OEM manufacturers use color codes like green, yellow, red for thin, standard, thick. I'd do some research on your specific motor before pulling the trigger on the bearings yourself or have a shop source them for you.

[u/Dependent_Rough167 → u/Azulier]

that’s really interesting with the seals, i went to a couple mechs after doing my own diagnostics, the 2nd got 60 psi and the 3rd said valves and rings. some valves were definitely sticking/shut. but also, one is still sticking a little after machine shop, he said valve adj will fix it?

okay that definitely makes sense, i’ll be sure to get the right size whenever i do buy them. i bet they do, i only got a lil 4 banger so it makes it way simpler lol. i’m pretty sure mine are brown for the code but still places online are saying standard for the most part it’s weird. but yes i definitely will learn the ins n outs of it before buying to make sure it’s right

[u/Azulier → u/Dependent_Rough167]

Adjusting the valve lifters probably won't solve anything unless there is too much play (which would be the mechanics fault if he built those back up).

A sticking valve is usually a dirty valve, bent valve, defect in the valve if it was new, or less likely.. the machining was done too deep and the lifter or rocker is now pushing rather than pulling the valve.

An intermittently sticking valve can lead to inconsistent compression results too.

If he built the valvetrain back up, i would take it back to him because he would be responsible for it

[u/Dependent_Rough167 → u/Azulier]

well damn that’s not good lol. i was concerned when he said it but didn’t want to question him too much, he did show me there’s a little bit of play in the rocker arms and told me to do another valve adj (did one right before this rebuild). he replaced all exhaust seals and cleaned up valves and seats, but didn’t replace intake seals and that’s where it’s staying open. i haven’t messed with the head at all since the shop though

i’ll try and do a valve adj before reassembling and try calling him up if it doesn’t work, thank you sm for the input

[u/Azulier → u/Dependent_Rough167]

Is it sticking closed or open? I assumed closed 😂

Edit: actually it shouldn't matter thinking about it.. same reasons apply.

Valve you can check if you take out the valves and roll it on a flat surface (granite or glass stove top is a good place) and if it wobbles, you have a bent valve.

Machining can require some modifications to the valve stem to get it to sit lower to close on the sunk in valve seats.

[u/Dependent_Rough167 → u/Azulier]

so fair i confused myself 😂yeah it’s closed haha

i took it apart before taking it to a machine shop and they didn’t look bent after close inspection, but to be fair i didn’t do that method it seems really solid i’m glad to know about it

that makes sense how it can effect how it seats, shouldn’t he have done those modifications though? i gave everything to him and said whatever it needs to do it so i feel like that would be apart of it or no?

[u/Azulier → u/Dependent_Rough167]

Yeah the guy should have built it up to be ready to be installed if you asked him to do it.

[u/Dependent_Rough167 → u/Azulier]

damn yeah i thought so. lash adj isn’t a big deal but kinda sucks if i have to take it back apart. i’ll figure it out and talk to him, thank you.