loweredf1 wrote:what causes a rod bearing to let go?
Lack of lube most times like cold oil, high loads/rpm or no oil.
You can also have problems with too tight of clearances or contamination when rebuilding, those usually show up very fast though.
If you smear or worse spin a bearing you will usually have oil pressure still, if you run it out of oil and smear or spin them all or most of them oil pressure goes down if it has any at all.
Here's a shot of my little oops, it smeared one side on this bearing which had no knocking from this cylinder for some reason
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on one other bearing it smeared right over the oil hole and still ran great, with a little knock
this sort of shows you how much unknown damage an engine can have and seem fine, like I said, the bearing in this pic produced no unusual sounds
Oh ya, the first thing I do always is cut open the oil filter, cut a piece of the accordian out and squeeze out the oil in a vice, then when you strech it out you can see what happened in there, you can run a magnet across it ti see if the pieses are steel or aluminun, not that it really maters cause if it's loaded the engine is coming apart anyway. It's a good first check to do to avoid running it to do other tests and maybe causing more damage
then ran through the gears at high rpm like 6500 when i hit 3rd it started knocking really hard. i drove it on home like 2 mile down the road and at around 2500 its knocks pretty bad but it doesnt sound bad idling. started it up again to pull out of garage again cold out and it sounded ok i didn't let it warm up though. what do you guys think could be making the knock? its a 418 stroker kit from mustang depot scat crank, h beam rods, forged pistons like 12.0 cr its a 2 bolt main with a trick flow girdel. cam is solid ftalt tappet with roller rockers and a stud girdel on them. motor has very low miles maybe 2000 3000. any ideas? 
