The PCV valve has two nips for lines, and only 1 line is running to it so it's sucking air. I noticed the evap can purge valve has a vac line running to it and the line is cut short and sealed on the end. Is it safe to assume this valve line is supposed to run to that open nip on the PCV valve? Couldn't find anything so I'm asking the question. Most likely I'll be replacing every vac line in this this thing



PCV valve

Evap Can and purge valve

 

Replacement PCV valves often have 2 ports(universal), and come with a Cap to plug 1 port if not needed, so just plug that port

The EVAP canister in 1991 has a vacuum line hooked to Ported Vacuum which is on the throttle body in front of the throttle plate, its on the under side, have a look for it and then trace the hose connected to it, it will most likely be broken and be long enough to match the EVAPs broken line



Gasoline engines have 2 types of vacuum
Regular vacuum is between throttle plate and valves, so inside the intake manifold
Ported Vacuum is between throttle plate and air cleaner

Air filter-------(ported)----------throttle plate----------(regular)------------intake valves(engine)

Regular vacuum is high at idle or deceleration, i.e. throttle closed
Ported vacuum is is almost 0 at idle or deceleration but is the same as regular vacuum when driving, throttle open

PCV Valve is there to suck out "Blow-by" exhaust from crankcase and it has a weighted valve, valve is sucked CLOSED by high vacuum, i.e. at idle when there is little blow-by, and then OPENS when driving and blow-by is higher

EVAP system is there to suck gasoline fumes out of the gas tank, create when gasoline is sloshing around in the tank while driving, so Ported vacuum works best with EVAP


Blow-by, any time a cylinder fires that explosive force causes some of the now burned air/fuel mix(exhaust) to "blow-by" the piston and rings and into the crank case, this also causes the Oil Vapor inside the engine, only thing hot enough to vaporize oil, just FYI
The valve cover areas are directly connected to crankcase by the larger drain holes in the head that allows oil to go back down to the oil pan to be recirculated
The blow-by gases are hot so rise to the top
PCV system sucks out these gases and re-burns them in the engine

 

In my junkyard run i picked up the purge valve vac line today, should be the right one. I'll put it on to the port its supposed to run to and plug the extra hole on the pcv valve. I covered it the other day and let it run for a bit, the idle mellowed out.

I also picked up the expansion plug I need to close up the cooling system but first I need to flush the thing as best I can and test the thermostat with some hot water, 200 degrees and it should flow i believe.

Preciate the input so far, youve been very helpful.