What are the symptoms of a stuck oil pressure relief valve? I had a fairly major engine blow-up a couple of weeks ago which I put down to a broken std rod bolt (rod through the side of the block etc). However on stripping the engine down it's obvious that the engine had siezed on number one big end and this caused the rod or bolt failure. All the other main and big end bearings had picked up as well. There was plenty of oil in the engine, the pickup pipe isn't blocked, the oil pump gears are ok and the (standard) relief valve seems to be moving freely. The engine also pumped a couple of pints of oil into the cam cover breather catch tank in the three or four miles that it ran before going bang. The top end seems perfectly ok with no signs of lack of oil. Any ideas on what caused this?
maybe the shell on 1 had just warn right through to the sub layers of the bearing. putting more strain on the BE. more friction, gets hot, seizes, bolt breaks etc etc. I presume the digi guage still showed oil pressure ?
I think the oil getting pumped out the breather is a vital clue - something had obviously gone very wrong with the oil circulation - a blockage of some description somewhere has occurred by the sounds of it - a stuck relief valve I don't think would cause what you've described.
it sounds like the bottom end was starved (duh), whereas the top end wasn't, and maybe got the extra oil the BE wasn't - get the crank feeds checked out.