Sudden complete loss of oil pressure?

[pidaster]

I recently purchased a rebuilt 360 with about 1k miles on it. Not sure what year the block is but my neighbor guessed late 60's or early 70's. The motor had been sitting in a shop with little to no oil for the last year. While installing the motor, we changed the filter mount out. The one that came with the engine was vertical and the one in my truck was horizontal. We didn't think the filter would fit with the vertical mount so they were swapped. After the engine was in and running, the factory gauge showed good oil pressure while in idle. While doing some other work, I let the engine warm up good but noticed the lower oil pressure than before. After all was done, I drove the truck a short distance down the road and back. About a block or so from my house I heard an odd noise but thought it was a leaky exhaust gasket. It grew louder and I noticed all my oil pressure was gone. I killed the engine and rolled to my house. I put a mechanical gauge on and ran the engine for about 5 seconds, no oil in the line or reading on the new gauge. I can hear the valves/ lifters making noise. I am running 10w30. Here's what I'll check tomorrow: Oil pump rod Will make a priming tool to see if that works. My neighbor says since the engine sat for a while that when I started driving and built up pressure the bypass valve might have kicked in and got stuck. How do I fix that? I really don't want to pull this motor back out. Murphy's law sucks.

[jowilker]

You are fine with 10W30. You don't know what issues the engine had when pulled. There were no vertical oil filters installed on 360s, as the 360 is a truck only engine. Your friend is correct in the late 60s (68-76) to mid 70s for the 360.

I will step aside and let an engine builder have at it, but I think you may need further investigating of what engine you actually have, and what problems it might possess.




John

[Hypoid]

Without looking, I think the bypass is internal to the oil pump. I hope your connecting rods are OK.

[Redmanbob]

Well since it still runs, ruling out the dizzy gear shear pin lol Bypass or the shaft broke or twisted into a pretzel. Maybe some of the old umbrellas went up the pickup and stupped the pump ?

[monsterbaby]

first and easiest would be to pull the dist and check if you can even see the shaft. But pretty much figure your going to have to pull the pan, broken shaft, bad pump, plugged pickup screen, and stuck bypass (internal on the pump) all will require the removal of the pan and those are all the most likely culprits.

[Krewat]

Definitely check that oil pump drive. It could very well be a bypass valve stuck open. Remove the oil pressure sender, and spin the oil pump drive with a drill (COUNTERCLOCKWISE) and spin it up to, say, 1800RPM or more. That'll be 3600RPM at engine speed. You should get SOMETHING out the oil pressure gauge tap.

If the distributor gear shear pin broke, the engine would stall.

But yes, you're looking at pulling the oil pan most likely unless something easy happened.

Originally Posted by jowilker

There were no vertical oil filters installed on 360s, as the 360 is a truck only engine. Your friend is co

4x4 trucks had the filter setup vertically.

[pidaster]

Oil pump rod was sheared off and bent like a pretzel just as Redmanbob called it. Took another oil pump rod and tried to turn it by hand but it's frozen up. Gonna order a HV oil pump with hardened rod.