I had the front cover gasket on a 302 "disolve", for lack of a better term, and the resulting paper shards found their way into the pan and clogged up the screen on the
oil pump's pickup. It acted exactly the same as you describe...no clicking lifters, no knocking bearings, just low
oil pressure until I shut it off, at which time the absence of vacuum allowed the shards of paper to drop off the pickup screen, only to be sucked back up once the engine was fired again.
The engine was in a Fox-body T-Bird, but I managed to replace the pickup by lifting the front of the motor and dropping the
oil pan far enough to get a box-end wrench in there. The engine ran just fine after that.
I'd try all the other suggestions, though, before I started taking motor mount bolts loose and scarring up your hands like I did...it was not a pleasant job.
Cheers!
Dugly
