Not sure if anyone remembers, but last April I had some oil pressure issues. At cruise, everything was fine, but at idle and stop/go situations in hot weather it was low enough that it would trigger the oil light. I changed the main and rod bearings, which the old ones looked absolutely fine, and the oil pressure was slightly higher (not great), but high enough that the light never came back on all last year. Just an FYI, never ever had a drivability/running issue because of this.
Fast forward, to around December/January. Head was off the do springs and fix a broken exhaust stud. Upon reassembly I picked the screen out of the cam bearing bridge. I figured it was easier to get rid of it than blow out for the 3rd time.
Last month, in this northeast heat wave we've been having, oil pressure light came on coming home from work in stop and go traffic. WTF.
I got to thinking, others have removed that screen without an issue, but with the screen in it must have been causing just enough of a restriction to get the oil pressure above the sensor threshold. Where else could I be losing pressure? Main and rod bearings are changed, head was off and looked fine....wait a second...the FUCKING BALANCE SHAFTS. The block I used to swap in was from a 2010 and had a 2009 build date. The earlier motors are the ones more susceptible to balance shaft issues.
So, Sunday I tore this thing apart. BOOM, front balance shaft had one of the ports completely blown apart and another was mushroomed out. Parts came Monday night. Back together last night. Drove it to work today. Pressure is finally where it is supposed to be. 25psi at HOT idle (as opposed to anywhere from 9-14 before) and 45psi at 2k RPM (spec is >2.7 bar at 2k RPM = 39psi).
So pissed I didn't think of this earlier, but at least now pretty much every single thing on/in this motor is new. I've found countless threads where people have these oil pressure issues and just end up swapping in a new motor, so I figured I'd just write a book about my findings. Also noticed the new balance shafts do not have reliefs cut in them inside the enclosed bearings or on the back end where it sits in the block.