sudden loss of oil pressure

something weird going on with my van that i love to drive constantly

I didn't get to drive my van the week I was at drag week then for maybe 2 weeks after due to floods and whatever. then a week ago I drove over to the next town about 13 miles, drive home and notice I don't have any oil pressure.

change oil and filter. change oil pressure sender. with a 1/2 drill 0-800 rpm with a mechanical gauge, it says 50 psi at full blast but if I run the drill slow half speed its at 25, slower and its like at 0. so I'm wondering at what rpm the oil pump spins relative to engine rpm. not sure if the gauge in the dash took a crap or if there is a problem. couple days ago, the mechanical gauge was reading near 0 when it was just idling but would go up to 25 when I revved it up. totally stumped

did you notice any weird noises?i don't think it would take long to start rattlin with no op.

oil pumps are cam driven so they should be half the crank rpm.

I just started it back up and its the same way. Very low oil pressure at idle. Hard to read exactly how low on mech gauge. Goes up to 50 if you rev it though. Lifters were ticking on startup

small block?

Yes small block. I just dropped the pan on my ramcharger but i dont think i can get the engine high enough in the van to pull the pan.

At the point of cutting pan and welding it back together or pulling the whole van apart and dropping in a reman engine and having trans rebuilt

what weigth oil did you use

try 20/50 see if presure gos up

my thoughts were to get the intermediate shaft out for inspection as a starter. there's a plug behind the shaft that if it's missing or fell out will definitely screw the oil pressure up.

A lot of miles ? valve seals stuck in oil pickup...

Did the small blocks come w/ the nylon lined timing gears like the big blocks did? That crap will get on the pickups also.

Its not the pickup getting clogged, that is the reason I just pulled the pan on my ramcharger. This is just different.

I just put 10-30 in it but was thinking I usually run 15-40 rotella in everything and thought maybe give it a try but I feel it just a waste of oil at this point

I had it out and was looking in the valley while I was running the priming shaft and didn't notice anything other then drainback

I'd throw another gauge on it just to rule that out.

make sure the "drainback" isn't coming from the back of the driver side lifter galley.

The pan on my 79 van came off with no issues, didn't have to lift the engine. Might have to rotate the crank to get the counter weights out of the way, but no big deal.

Make sure the pickup didn't Crack or fall off

I saw this happen once on a small block oil pump. A piece of debris stuck the relief valve open.

if the thicker oil picks up oil preasure then its time to rebuilt it

my 340 did this and with a new oilpump but at high rpms it would drop off

just save the oil for next time

79 must be different than a 77 because i dropped crossmember 3" and have engine jacked up 2" and i still cant get it off

pressure relief valve was stuck open. popped right back into place but I'm changing the pump.

Nice find and soon you`ll be cruizin again.......