heavy, BLACK sludge in recent rebuild

[flatlander]

The bits you see on the oil pump screen have a rubbery consistency and the bottom of the oil pan is covered in a thick, black sludge. I have only a couple hundred miles on the motor since a complete rebuild. I have not been driving it because it would not maintain any oil pressure at idle; would get to about 35 lbs at 2500 RPM and above but drop back to zero when allowed to slow back to idle. Pulled it apart to replace the oil pump; the oil in the sump seemed pretty normal: no bad smell, no obvious discoloration, but the stuff on the bottom of the oil pick-up and in the bottom of the pan is just nasty. I am hoping someone can give me some insight as to what I may have done wrong; any advice or suggestions will be appreciated.

[spiderrey]

Just a long shot guess here. Someone used a lot of silicone sealer on the gaskets and it got into the oil system.

[So Cal Mark]

it does look like rtv to me. Post a pic of the oil pan

[narfire]

Good call on the silicone sealer.
Take a look at the surfaces where the silicone was/could be used. If there are great gobs hanging out the side you can see, be assured the same inside.

[flatlander]

Thanks for the input. Unfortunately, I already cleaned and reinstalled the oil pan. No silicone gasket sealer. I did the build myself and the only gasket sealer I used was Copper Coat.

[htchevyii]

Assembly lube?

[flatlander]

Trey: I'm not at all sure what you mean by 'assembly tube'

[So Cal Mark]

rub one of those bits between your fingers. If it's sludge it will smear on your fingers, if it's rubber or rtv it will be obvious. If you didn't use rtv I'm thinking it's pieces of a seal

[htchevyii]

Trey: I'm not at all sure what you mean by 'assembly tube'

That's lube, like moly assembly lube/grease?

[azruss]

the question i pose is did you disassemble your oil pump to see if it was contaminated with this mysterious black goo. that may be the issue of your low oil pressure issues. Also need to blow out the exit tube to see if it is clogged. May also need to pull the oil filter to see if any contamination got to that point as well.