1985 k20 350 sbs 4sp Manual. Recently lost all oil pressure had 30 have 0. No strange noises. DID NOT OVERHEAT. Considerable Loss of power. I was told since engine had a severe lack of power and no oil pressure that new engine would be needed $5000. Did not have the money so I pulled engine, disassembled and inspected. Found that oil pick up for pump was unattached and that oil filter was clogged. All bearings looks ok. No scarring on any parts at all. So my Question is Why did the engine have such a substantial lack of power? Obviously now I know why I had no oil pressure

 

I thought I should post the great advice I received on another board. Hope it helps. It definitely helped me!


1st responder
"Oil may have burned off cylinder walls causing rings/pistons to drag hard... overheated, swollen pistons dragging against cylinder walls... spraying oil cools the pistons... dry bearings turning hard... possibly hot engine was detonating mixture in some cylinders before pistons were up high enough and trying to force them back down backwards... hydraulic lifters collapsed without oil pressure, giving the effects of a much smaller cam... You should have heard lifters clacking... If you're lucky, you shut the engine down before serious damage"...
2ed responder
"If you have an electric choke and your wiring is still stock then your loss of power is caused by the choke closing. The power to the choke is wired thru the oil pressure switch. No oil pressure shuts off the 12v to the choke.
It was a safety kinda thing. Choke closes, motor won’t run, you shut it off and the motor is saved."

 

Interesting - I know fuel pumps can be shut down by the oil pressure switch; never heard of the choke scenario. Let us know status once you get it running again; good luck!