While reading through the military spec manuals I've encountered a few questions...If I'm reading it correctly they're calling for 15-40 wt oil...Which lead me to try and figure out the route of the oiling system...Does anyone know the routing ??? There's no actual oil passage way diagram showing the flow of lubrication but with the pics I've collected I think I have it figured out so correct me if I'm wrong...When I get to the point of needing to tear one down I'll get detailed pics but for general routing Here we go.... Oil in the pan goes up through the check valve into the oil pump...From the pump it flows to the crank... Here's a pic of the 084 crank1647 it seems to have oiling journals on the mains and the rods...And a pic of the crank main bearing...1648 it has full groove bearings which is a good thing{the full groove bearing keeps oil flowing at all times instead of only when the oil holes line up during rotation} and I'm assuming the cam would get it's lubrication from one{or more} of these bearings.... Now, here's the thing...If the crank has oiling holes for the rods and the rod bearings look like this..1649 would'nt that mean that the rod bearings are pressurized ??? I also see the piston/rod combo has what's called a "full floating" piston pin which means it rides on a coating of oil{instead of being pressed on the rod} and is held by a retainer ring in each end of the piston seen here...1650 and that end would be lubricated by either A}an oiling hole from the rod itself or B} is splash lubed by the slinging oil...
I can't find any pics of the pushrods but I'm assuming the rods are hollow and the lifters are pumping oil through them into the heads and the heads have the external oil returns {rubber lines} back into the block.... Did I get this correct ???

As far as I know the main bearings are pressurized but the rod bearings are not. I'm not sure how the oil gets to the cam but there is plenty of oil in there when you take off the cover at the cam gears. all your statements sound correct.

this is not picture of the 4A084 motor, but is an example of the flow of the oil in a 4 stroke motor.
it just doesn't have the lifters and push rods on it.
and yes, the oil is forced into lifters, which should have and internal spring and pressure plate in them, (it has been a few years since I have taken one apart.)
oil is then fed through the hollow part push rod. (see the little hole in the end of the push rod in the picture below) that keeps the socket of rocker arm lubricated or it would wear out real quick.
hope that this can answer any questions

Refresh my memory ... Does the 084 have hydraulic lifters?

you made me stop and do a double think.
pulled up some information from http://www.dtic.mil/dtic/tr/fulltext/u2/756511.pdf on page 4, it gives the description for the 2A016, 4A032, both which have solid lifters, and the 4A084 has hydraulic lifters.

with solid lifters, you have to use feeler gauges and adjust the valve backlash, and the push rods would should be solid, to handle the constant slapping.

when i opened up the valve covers and took off the rocker arms, and push rod tubes, the other day. i just assumed that they were hydraulic lifters, because there were no adjusting screw on the end of the rocker arm that goes against the push rod, and with the hollow push rod tub. and not seeing any way to adjust for the clearance. it is good to stop and verify what i am putting out there is correct information.
( i remember adjusting solid lifters on some old V8's back in the day, on some rebuilds. what a pain in the rear. but that is another story)

I have started putting together some pictures of the oil flow for the 084 motor. it will be a work in progress, I will be using one of my 042 motors for most of the interior motor pictures, ( really don't want to take apart my 084 motor)
hope that this will help with many of the questions that have been asked.

the plug with black circle is the start of oil galley through the bottom of lifters and goes all the way to front of engine and crosses over to left side back down to the end of block. i think the galley is what feeds oil to the mains and supplies oil to the lifters and camshaft. only way to find out if the rods were pressure fed is see if crank has a hole in the gernal for the rod. there is a plug in the block behind the fuel pump you can hook an oil gauge to.

only way to find out if the rods were pressure fed is see if crank has a hole in the gernal for the rod. That's why I originally questioned the rods being pressurized...If you look at the 084 crank I posted it has the oil holes in the rod journals...The rod bearings also have holes in them...

If that oil galley needs to pressurize from the oil pump forward then all across the front of the block and back down the other side that would explain why the lifters take so long to pump up as Papee and Aerokirk have stated...

If my poor poor memory is working I seem to remember that the rods are oiled but the mains are not,

last night dismantled one of my 042 motors, the only difference between the 084 and the 042 is 2 less cylinders, and a shorter case. I don't have the center support web in the middle of the case to support the center main journal of the crank shaft.
I outlined the different galleys in
red for suction
blue = pressure line feeding the pressure relief valve, governor and crankshaft.
yellow = pressure line feeding the lifters
black = oil returning the oil pan
it was kind of interesting looking at the tail end of the camshaft. there is the cut out to allow oil to pass by, and continue on to the crankshaft. but there is a flat spot on it, that matches up to the oblong galley passage, just past the down port that feeds oil to the crankshaft. so on every rotation it will send some oil to the lifters, maybe this will reduce the full pressure to the lifters, I don't know. just kind of interesting.
I guess I could take out the plug that is on the side of the motor, just behind the lifters , ( they used some Loctite on it. thinking I need to apply some heat to it, for removal) and stick a pressure gauge there, just to see if there is any pressure drop.
but the pictures are pretty marked to show where everything is going. I didn't take any picture of the crankshaft, figured that there was no need to explain and mark the oil journals on it.

I have a few more pictures, one of the things that impressed me was that there was still some good crosshatching on the cylinder walls. and very
little wear on the rod bearings. the rod journals only showed some wear on the piston side, only.
if you look at the inside of the case there are weep holes right above the cylinder, that drain from the front of the lifter, which could help with splashing some oil film into the bottom of the pistons to help dissipate the heat
not bad for generator motor with over 1800 hours on it.
I did a compression test on this motor, when I picked it up. and both cylinders had 125 psi.

a couple more pictures, showing the passage ways for the front and back oil galleys that pass by the camshaft. on the rear of the motor, you can see the single hole in the front, it feeds by the recessed cut out on the camshaft. and the oblong hole is fed by the flat spot, that is in front of it.

about the same on the front. except the oblong hole is the main galley feeding down to the crankshaft.
there is a small hole you can see in the front bearing on the camshaft, that allows oil to the inside of the bearing.

i highlighted the plug that you could remove and plug in an other pressure gauge to, so you could see what the pressure is, that is feeding the lifters
it felt pretty snug, I think it was installed with some good loctite, might have to apply some heat to it to free it up.

Great info and excellent presentation....Thanks for taking the time to document the oiling system that takes the mystery out of the oil routing...You're right that engine appears to be in good shape I hope you've kept the lifters in order to match back up to the cam if you plan on running it again...

I guess the wrist pins get splash oiled from somewhere...