Recently purchased 1984 s10 blazer. front says 2.5l but when i shop for parts im having to use 2.8? now ignoring the joke of no room and metric everything....i am used to working on vehicles and am familiar with parts/functions etc.
So i started an oil change right after purchasing the rig because the previous guy had told me there was a small leak. I assumed old gasket or unevenly secured pan. It wasnt enough i noticed it when i test drove it, but the oil was really low and it didnt overheat on me so i didnt check the oil level at that time, only looked for a visual leak. Needless to say i was more than thrilled to find out the pan doesnt come out without disassembling the front passenger wheel assembly or removing top components from the engine and then raising it.
So the leak i noticed before removing the pan bolts was accumulating on the top of the front diff and then pouring onto the ground from there. Attempting to avoid fresh warm oil in my face i tried to see the leak (engine freshly off) before the leak stopped from underneath.
As far as i can tell its near the oil pressure sending unit but it isnt the unit itself (the leak is near the unit ACROSS the block). It runs along the cast for the oil pressure unit and looks to be coming from an opening (maybe 5/16ths diameter?) that is along this part of the cast. I thought it was the dummy light spot for the oil but i was mistaken as this hole has no threads whatsoever. Now a few inches further along the block is another hole with what looks to be freshly leaked oil around it. This hole however has a bolt threaded in (not completely) and i believe i saw a locking washer on it too.
Can someone tell me what this random bolt is im seeing and if the bolt should be completely flush to the block as well as the other holes purpose or function?
Again i cannot tell specifically where, this particular spot on the block is where it appears to be starting (following the flow...).
The oil filter is just above all this, and it has been removed, the seals checked, and replaced with no sign of fresh oil on it anywhere (in case someone wants to suggest that, i got it covered).
I suspect its the mysterious holes as my gasket is in and holding perfectly currently.
I can see the area im describing only while under the vehicle and not with the vehicle on; my face needs to be where the leaks pours down on to see these spots while the engine is running.....but i dont have a crazy desire to have any more oil in my blood than what seeps into the bloodied knuckes thank you very much.
Any help or info would be greatly appreciated.
PS i am new to your site, but not these types of vehicle forums, so i apologize if i posted this in the wrong section-i thought i followed newbie rules properly.

 

is it a v6 because if it is look into by the distributor those motors like to leak from around there from cheap orings being used

 

Yes it is a v6. I checked the dizzy after browsing the forum here to see. I have no leak from that part of the engine-I'd assume the ring is fine.
Since posting I've cleaned the engine of gunk and grime to make sure no leaks I missed are present. It is officially only near the block /oil pan/oil pressure sensor area.

 

Unfortunately, these pics are all BEFORE cleaning and replacing the oil pan gasket. I still have no idea what this area is technically called on the block, or what the holes are for/bolt as well.
As near as i can tell, i stopped the leak via the old gasket scraped off and new one applied (and pan tightened....the bolts for the pan in the same area as circled were such a B!tch to get to!)
First two pics are from the driver side wheel well looking into the engine bay;
the third picture is from underneath the drivers side looking up into the engine bay.

 

keep in mind that oil leaks are usually the highest and most forward area of the wet mark
Gravity and wind takes it back and down