I do not get a dash light so I am not sure if the light works or there is another issue. Where do I begin?

with dash light disconnect wire to sender switch and ground it with ignition on. If light glows sender is no good, if no light check wiring and sender.

If you have oil at sender switch port remove tappet cover and loosen centre rocker post. You should see oil run out when turning engine with key, easier with plugs removed. If you have oil there rocker shaft is probably sludged up. you can remove rocker assembly and pull end plugs in shaft to clean, leave pushrods in situ to make lash adjustment easier.

Okay, think I have problem resolved. I poured a bunch of Marven's Mystery oil into one of the removed rocker arm shafts. After a few pours, I would turn the engine on to see any results and after about the third time, oil appeared to be coming out of the small holes. I could tell I was on a good path since I could see the Mystery oil pouring from various minute crevices and even from the top after a few pours, so I knew things were clearing up. When the engine was running, the oil coming out was like little rain drops of oil spraying from the holes. I will try again later to see if I get similar results. I am waiting on new injectors to finally wrap it all up.

You could soak the whole rocker gear in diesel for a few days and then wash it out with fresh stuff. Would be better to strip it all down after the soak to clear all of the old dirt and carbon.

I had a similar situation years ago with a freshly rebuilt B18, turned out to be a bad oil filter. Remove oil filter, crank over engine, watch for oil exiting the threaded pipe. If none you have an oil pump issue. Deloc

Good news...I removed the oil filter and turned on the engine and it was like a flood as to how much oil came out. So, it appears the oil pump is fine. Also appears the issue is a blockage between the filter and the top of the cylinder head.

Remove sender switch and turn engine over by key. Oil should gush out, if it does replace switch and check wiring and bulb. If no oil i would think you would have destroyed engine by now.

Are the rocker arm posts in the correct order?
--
Three 164's, Two 144's, One 142 & a partridge in a pear tree.

I don't understand what you are referring to.

One of the rocker stands takes the oil feed from below and distributes it into the rocker
shaft. It has a bigger hole. But if the engine has had satisfactory oil pressure since
the rocker stands have been off or disassembled that is not the problem.
If your distributor is turning OK and you still don't have oil pressure you are going
to have to get into the oil pan to see what the problem is. There are several possibilities:
Broken oil pump shaft
Blown oil line seals
Seriously damaged oil pump
The easiest way to get into the oil pan is probably to pull the engine, although it can
also be done by suspending the engine and dropping the front crossmember which includes the
whole front susupension. It is a big job either way.
Tough luck!
--
George Downs Bartlesville, Oklahoma

One of the rocker stands takes the oil feed from below and distributes it into the rocker shaft. It has a bigger hole.

In fact, that's not so. They are all the same on a B18/20 and can go in any order.

I had a vision of a tapered hole somewhere there, but that is in the top of the head.
--
Three 164's, Two 144's, One 142 & a partridge in a pear tree.

Couple things to do at this point.
Open the oil filler cap and look inside. Is it oily in there? If so you are probably getting oil.
Check the oil pressure switch down by the oil filter and make sure the wire is hooked to it. If it is unhooked the light won't work.
--
George Downs Bartlesville, Oklahoma

Also, I checked the the oil pressure switch and it all connected. Did not see any breaks in the wire either.

Steve

George,

It is not oily at all on top when I remove the valve cover. There is no oil coming through tot he top.

Is it showing oil pressure otherwise? (Idiot light shutting off upon engine start, or a gauge showing pressure?)

I just realized my check engine oil light does not work so to answer I don't know.

There is no "check engine oil" light on a 140 or 164 series Volvo. The oil pressure light on the instrument cluster should only illuminate when there is no oil pressure while the engine is in motion.

The light should come on when the ignition key is in position 2 (KP II engine not running) and go out shortly after the engine is started.
If it is not going on in KP II (engine not running) then you may have a bad bulb, sensor or wiring.

Fix it. You really don't want to be driving around unable to have any idea whether you have oil pressure or not.
--
"Differences of opinions should be tolerated, but not if they're too different" - Sharon Craig

The only way I can think of to differentiate between a bad oil pump or just simply clogged oil passages to the top end would be to attach a gauge in place of the oil pressure sender (or in ADDITION TO the sender using a "T" fitting).