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Discussion Starter #1
Completed build:
D16Z6, bored block (75.5), port and polish head (3 angle VJ), new springs, retainers, stock valves, stock cam. New everything on bottom end; except oil pump, rods. Oil pump works fine, rods were straight, had crank micro-polished. +10 sized bearings for main and rod.

Anomaly:
Had everything working....everything plasti-gauged perfect, clearances perfect, buttoned up just fine. Oil pressure was good. Ran perfect on start up, no smoke even!! Idled and got fuel dialed in, idle dialed in, for 3-4 hrs. Idled FINE not a sound.

>Now....had it on the dyno.....immediately under load started hearing knocking from bottom end......which lead to the #3 rod bearing tearing itself apart, and most of the crank journals are all grooved now. Murky flakes of bearing matter in bottom of oil pan. A lot.

What could of caused this? The shop mechanics are even baffled.
 

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Discussion Starter #4 (Edited)
did you have the right pickup tube for the motor and pan?
Yes. Pressure looked good across the board. Oil drained out fine too.

did they polish the crank in the right direction?
Pretty sure....I can call and double check. Reputable shop with like decades of experience.
- Grooves were pretty substantial, could feel it on your fingernail; only 2 pulls on dyno too.

EDIT: Called machine shop and it was ground in proper direction.
 

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Discussion Starter #6
something in clearances was not right or it was not broken in properly...other than that maybe just faulty bearing?
That's the strange part, EVERYTHING was within clearance, and within tolerances. To be honest I thought I would encounter a problem during assembly for those reasons, but nope none.

Do bearings go bad that fast? They only did a few pulls.
 

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Discussion Starter #8
ha, yeah for sure. This is only a little guy, mostly stoke that now breathes better :)

Any and all comments welcome because I'm looking at buying a new crank now, bearings and rods too. This is ending up costing me out my ass now.
 

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Do you have an oil pressure gauge hooked up? If so, did pressure fluctuate before it let go?

Also, could be clogged oil galley; with debris from break in?
 

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Discussion Starter #10
Do you have an oil pressure gauge hooked up? If so, did pressure fluctuate before it let go?

Also, could be clogged oil galley; with debris from break in?
-Not sure on pressure fluctuation....I'll check.

-After break in oil was drained out for next round of oil, the pan was clean, no metal debris at all. Just used oil.
 

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-Not sure on pressure fluctuation....I'll check.

-After break in oil was drained out for next round of oil, the pan was clean, no metal debris at all. Just used oil.
even if it just looked like used oil or film there could have been traces of metal shavings and that is what probably wiped your bearings out
 

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Also, could be clogged oil galley; with debris from break in?
I'm going with this.

You would have still seen pressure on the gauge, but your bearings would have been starved.

Get the girdle off and take out the big hex plug.
 

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Discussion Starter #14
even if it just looked like used oil or film there could have been traces of metal shavings and that is what probably wiped your bearings out
Nope no metal shavings in it at all. They used a magnetic tray inside the oil pan to catch anything.

Also, the amount of grooving on the crank journals was bad, in such a short amount of time too. Oil starvation has to be the culprit, but from where?

This oil pan, pick-up, and pump all sat for 6 months with dirty oil in them too, but he had cleaned them out to make sure, like really well. Still think the pressure dropped too low on high revs....
 

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Discussion Starter #15
I'm going with this.

You would have still seen pressure on the gauge, but your bearings would have been starved.

Get the girdle off and take out the big hex plug.
Yeah I agree. After thinking this over and over I still think it is an oiling problem. I will relay this info. on. Thank you!
 

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95 VX, 88 S/C MR2
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oil pump could have cracked a gear, had this happen to me with my mr2, kept oil pressure up to a certain rpm, then dropped like a rock.
 

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Discussion Starter #17
oil pump could have cracked a gear, had this happen to me with my mr2, kept oil pressure up to a certain rpm, then dropped like a rock.
Yeah we took it apart and there weren't even hairline cracks. Still think the galley's were clogged up. All it takes is just a few seconds of no oil to F it up.
 

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bearings too tight. thats why it idled fine with plenty of pressure (good oil film for NO load) but as soon as you put the load to it the oil film is squeezed away from the bearing surface.

that is the ONLY reason multiple bearings would let go that quick, unless of coarse oil pump failed.....

if you idled that long without a sound then you had descent oil pressure.
 

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Or oil contamination? Did you change the oil after initial start up to clear out any shit and assembly lube, before you hit the dyno?
 
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