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I've done about 200km of driving on my freshly built rb25/30 and I dropped the oil for its first change. The oil had that slightly metallic sheen of death so I cut open the filter and found a fair amount of very fine pulp of what appears to be iron as well as a small number of small pieces of Copper (Assuming bearing material)
The engine has no rod or bearing knock noise. And 30psi of oil pressure at warm idle.
I fastidiously checked bearing clearances when assembling and crank/block straightness. All the rods were at 2thou and all mains were at 2.7-2.8thou. Oil pump is a reimax geared rb25 pump block runs twin 1.2mm restrictors, stock sump.
The engine runs well however does do a weird thing where if it's been driven a little bit harder it won't idle afterwards for a few min. I assumed that was just a tuning bug.
-Where have I gone wrong?
-What should I do now?
-The initial run in oil was 10w40 would that have possibly been too thin to maintain oil pressure at higher RPM with looser clearances? Current oil is 15w50 ten tenths
-Is it possible the stuff in filter is mostly from bedding the rings in?
You may very well be worrying about nothing. During the initial break in there is a significant amount of material that ends up in the oil as part of the normal bedding process as the rings take the peaks off the fresh hone pattern. This will result in a metallic shimmer in the oil and can also be seen as metallic residue in the oil filter. What you shouldn't be seeing is copper from the bearings though. If in any doubt I'd suggest you drop the sump and check the bearing condition. It can offer cheap peace of mind if all is well, however if you catch a problem early it's also going to potentially save you a lot of money.
Thanks for you reply Andre. I know we all appreciate your guidance. I took the car for another brief drive and let it idle for a while a few times then pulled the filter again. The amount of material in it was far far less than the first filter and none of it appeared to be bearing material. I'll repeat that process again with another filter. I think possibly something scratched a bearing on initial start up but isn't causing any further damage. Or the first filter got so clogged that the bypass valve opened and sent something through the system.
Just keep an eye on everything. Good luck!