hippystyle

Hello Yota lovers.
First off this is my first post mainly because you guys do such a good job of answering every ones questions ive never had to ask one.
anyways I have a 88 4 runner i purchased with 149000 miles the owner had not used the truck in 5 years but took it to jiffylube once a year(veterans day) for his free oil change
after about 4 months of owning it i started hearing a knock at startup for such a short time i couldn't get out fast enough to find it
after awhile the duration got longer and i was able to find it was coming from oil pan. i would also here it slightly after offroading in 90 degree+ for an hour or two
first thing i did was pull the pan found 1-2 inches of sludge and a half clogged pickup tube and lots of copper/brass shavings bingo main or rod bearings right?
pulled the motor apart both look good even took them to my machinist he agreed looks like the came from a 149000 mile engine.
the motor did have a headgasket leak which had stopped before i got the truck(stop leak) SMH but coolant was still getting into the cylinders as i would find out after pulling the pistons
pistons have scoring on the skirts i miked them and found 3.442 on the worst scored to 3.444 on the least scored. piston skirt collapse? is that my knock if so where is all the copper/brass coming from?
also wrist pins according to the "book' are good buPt they are brass looking i haven't pulled them yet, am i missing something here could it be the oil pump coming apart is there copper in there (seams unlikely)
I'm doing a full rebuild anyway since I'm going to be taking the truck up to 50 miles outside of any cell service or people. Its just driving me nuts not finding the culprit
any thoughts would be great thanks in advance
Jeff
P.S all these emojis are awesome

coopster

Ever find the culprit?
Oooh. See you're from S Utah. Get washed away? Saw pics of Zion, big bolders (neh, chunks of mountains!) in the road. Guess Virgin ran pretty hard. Was just there last month with my daughter.

hippystyle

No I never did find the culprit just gonna replace it all and cross my fingers. I'm north of the Virgin so not to many issues here as far as flooding but we had some great days mudding