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Piston replacement

SnowTh1ef

SnowTh1ef

New member
Trying to gather some opinions.

One of my cars, 2000 Bonneville SLE, Topswapped, had a clogged cat and ended up chipping a piston. It still runs good, just burns quite a bit of oil and has about 40 psi of compression in cyl 2.

my other car, 00 camaro, also topswapped, spun a bearing due to water getting in the oil.

Should I be able to just take a piston out of the camaro and put it in the bonneville?

Would I be able to reuse the rod bearing, rod bolts etc? Or should these be replaced.

I would basically follow this procedure http://www.3800pro.com/forum/general-tech/21127-rod-bearing-replacement-car.html

But also remove the rear head, pull the piston out, etc. Correct?
 


yeah, was going to only bring over the piston from the spun bearing motor.

So it's ok to re-use the stock rod bolts even though they are TTY?
 
yes, however if the bolts feel to "loosen" as you reach tq spec, remove and replace with another from the donor motor.

its not often a TTY bolt goes fully to yield on the OEM tightening so you can generally get at least one reuse out of em
 




Reptile said:
I wouldn't recommend reusing the bearings and the rod bolts....I'd even say put new rings on the piston.
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yeah im sure he wants to hone a bore with the engine in car and assembled.
reusing the bearings is fine, at most id be leery of the rod bolts...but just cause a manufacturer uses a TTY bolt doesnt mean that its hit its yield point....simple inspection can find stretched threads, etc. the feel of the fastener during tightening is good feedback as you may hit the yield.

ive reused cam bolts (funny how a non necked down bolt uses tty fastener tightening...yet its not a yieldable fastener) flexplate bolts, rocker bolts. very few actually yield even the second time being tightened.

the whippled Riv's L32 shorty is using the original bearings and rod bolts (none yielded) and has over 15k miles and plenty of WOT pulls

SnowTh1ef said:
think i should put new bearings on just the one rod with new bolts? and new rings?
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not unless you see bearing wear...ive seen the oem aluminum bearings at 160k with barely a shiny spot...these arent the same soft bearings as the old trimetals. i wouldnt use the bearing from the rod knocking motor but chances are the chipped piston bearings are fine unless you had repeated and prolonged detonation...inb which case youll see the bearing shell curl inward from the hammering.

the new bolts i wouldnt worry about, chances are youll have no problem tqing the oem bolts, and if one yields and gets easy to turn near the terminal Tq, you have 12 spares on the stand next to it.

as for the rings, just reuse the ones from that bore taking note of the gap positions for reinstallation.

all youd have to do is lay the top and second rings next to each other to determine if the top ring may have warped at the missing ring land...if it has just use the top ring from the junk motor and scuff the ring's bore face lightly with coarse sand paper to give area for oil reservoirs as the ring wears to the new motor that wears in nearly the same manner in all bores. which is quite bad but thats due to the high rod angularity.

normally i wouldnt suggest this path over a new jy shorty but any asshole that tackles a rwd l67 swap into a "hey lets put the motor under the ****ing dashboard" 3800 car can probably tighten bolts properly and keep his tools and parts/workarea clean enough to pull off this repair.

make sure you clean the inside of the sockets, its amazing how many people forget that clean tools are important as much as the work area/parts, steal the sink utensils, yer old lady probably wants new ones anyways.

bucket of kerosene and cans of brake cleaner
 
Turbocharged400sbc said:
yeah im sure he wants to hone a bore with the engine in car and assembled.
reusing the bearings is fine, at most id be leery of the rod bolts...but just cause a manufacturer uses a TTY bolt doesnt mean that its hit its yield point....simple inspection can find stretched threads, etc. the feel of the fastener during tightening is good feedback as you may hit the yield.
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Well, alright then.

Have fun with it.
 


try it sometime with some used OEM crank bolts...those are the only ones i have a fair amount yielding on the 2nd tq, and thats largly because of the small dia thread and short length versus the high clamping requirement.

you can feel when the fastener yields as you come to the end of the final degrees of turn sequence.

the longer the bolt and the larger the dia the less likely your gonna hit the actual yield, case in point is ive reused plenty of rocker bolts, same thread and tightness as the crank bolts, and ive had only 2 of those yield on me vs dozens of crank bolts.

for the rod bolt tq versus the thread and length...its not likely to yield, but if it does, youll feel the bolt get easier to tighten as you come to the final few degree's of turn, stop before it snaps, back it out and toss another one in.

in the standard of "dont rebuild it just get a new shorty" thats repeated verbatim for the noobs... a guy that has a good tq wrench and feels can fix this since its "junk" anyways.

years of beating the piss out of used L32 rod bolts has me confident enough that id suggest it
 
I was just trying to say that while you're there it's only a few more bucks for new parts. I've seen a few times where tty bolts HAVE broken, and other times where they are fine (like the cam bolt) . The two that I never reuse are the rods and flex plate. Just my opinion.
 
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