OK, here is a pic. I took a better look at the hole this time. It is an oil passage and the wire is red with a white stripe. So i got a new oil pressure sensor and screwed right in. The ensuing story is how this started. It should make you laugh. This is my 19yo son's first car, 97 B2300 I picked up for $1,700 bucks.
#1 - he called me in the morning and truck is running really bad and won't maintain an idle. I told him to limp it home.
#2 - next day I pulled the codes and it was just the MAF sensor. By chance I pulled the dipstick and it was bone dry. WTF!!! Called it a day and went home.
#3 - That night my son and his friend (they act like Bill and Ted's excellent adventure when they are together) decided the motor is bad and they're gonna do a V8 swap!!! Proceeded to pull EVERYTHING off the motor and get ready to pull it.
#4 - I show up the next day and WTF???? Ok, deep breaths. We're at the point of no return so might as well pull the motor and pull the pan so I can check the bearings, rods, cylinders, etc. Everything looks good. Those LIMA motors can take a beating, lol.
#5 - OK retards start cleaning the engine bay and everything else so I can eat off it. I'll start ordering stuff and replace all gaskets, seals, timing belt, clutch, MAF sensor and the other usual stuff.
#6 - Fast forward two weeks and today we got everything back together and it fires up on the first pull.
#7 - About 2 seconds later I yell SHUT IT DOWN, SHUT IT DOWN!!!!. FORGOT TO PUT ON THE OIL FILTER!!! And now nothing is clean anymore, lol.
Called it a day. Went home and back at it tomorrow.