Fresh rebuild, 8 miles, spun bearing, 'stuck' wrist pin?

[ziggo0]

I did a rebuild of a 6 bolt I bought off a friend. It was bored 0.030 by a reputable machinist. He also did the 1g rods to accept 2g pistons and mounted them too. I put the build together over a few days, bottom end went together very nicely! New Clevite bearings, standard size as crank was in std condition. All bearing clearances were within tolerance. Piston ring gaps were 0.019 & 0.024, everything torqued to spec from the oil pan bolts to the cam cap bolts. Assembly lube on all rotating surfaces (not back sides of bearings). Primed oil pump with an impact gun, ran it long enough to see oil in the head/turbo feed (oil pump is new also). Running conventional 10w30 oil, 4.6 quarts of it.

Started it up last night and it fired after the 2 time turning over and went straight to 750rpm and idled for about 5 minutes around 900, no surging or anything. Went to go do the break in for the rings (4/5.5k rpm, 2nd and 3rd gear decelerations for about 10 to 20 miles). At about 8 or 9 miles I started to get rod knock, not lifter tick. Get it back to the garage, drop pan, lots of metal shavings, rod 3 had spun. There was about half of the bearing left for each one, crank looks a bit torn up but nothing a polishing couldn't fix - this is not what concerned me however.

When I took the rod cap off and went to push the piston/rod up...the rod did not want to freely move on the wrist pin. Before the build and install it moved just fine, was lubed up plenty and oil squirters are installed. It can be moved if I force it to, it doesn't take he man strength to move it but it takes take a little convincing - does anyone have an explanation onto how this bearing spun and the rod is seizing up on the wrist pin? I'm going to call the machinist tomorrow and get his opinion but I'm in a bit of a panic now because I no longer have a ride!

Didn't realize I put this in the Newbie section, my mind is very scattered with this sheer stupidy of this happening.

 

[BogusSVO]

was the crank polished? did you do a final clean of the crank?
Did you gun brush out the oil passages and wash them out just before the install?

I have come to lean that alot of spun bearings on new rebuilds are from the crank not being cleaned befor the install.
when a crank is polished, grit from the crank polishing belt builds up in the oil passages. then when the enging is primed, started up it forces the grit from the oil passage in the crank right into the bearing.

how did that rod/piston combo feel when you installed it? did it move freely? or was it a tad stiff?

some grit or bearing trash may have worked up into the piston, being caught betwen the wrist pin and piston causing it to gaull.. the other way I see this happing is the oil squirter got clogged and starved that piston for oil. (but there are many engines running with out squirters) the third is that that piston has some issues when installed on the rod and the wrist pin to piston clearance got distorted.

get the engine popped out and post some pics of the damage

 

[soulefood]

the wrist pins should be pressed onto the rods and the pistons should "float" on the wrist pins.. this keeps all the wear on the piston skirts not on the rod ends... if the pins moved inside the rods then this was done wrong.. however this would not cause a rod bearing to spin.... post machine work cleaning is essential to a good running motor... the block, crank rods.. everything should be rinsed in HOT fresh water... i know this sounds stupid cause water allows iron blocks to rust however this is essential to cleaning the block... immediately after you rinse it, it should be blown out with compressed air and assembled.

 

[donaldseclipse]

this just happened to me i am taking the block to machine shop to grind crank. im going to get new bearings, pistons and rods.

 

[eclipsek17]

Just happened to the new talon I just bought. I had it for 3 days and it spun a bearing. Guy I bought it from said it was just rebuilt and not even broke in yet. I got about 20 miles of babying it, then heard it all happen. Now I have an eclipse with a seized engine, due to front main seal blowing out, and a talon I have to rip apart the bottom end on to see if I can salvage it.