Oil Pressure & Flow

Lubrication System (oil feed pump and scavenger pump, reservoir, filter, and lines)
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Hauula Pan
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Oil Pressure & Flow

#1

Post by Hauula Pan »

I recently put my engine back together after it sat for several years. Its currently .060 over with low compression pistons. Starts & runs fine but I notice that when I first start it I have around 32lbs. of oil pressure & my light stays out. As it warms up the pressure drops and the light comes on at idle. When its fully warm the pressure at idle is 0 and barely reaches 2 psi when rev-ed up. and the light pretty much stays on even at running RPMs. I have oil returning to the tank but it is not a smooth steady flow. When warm and at idle it has an erratic spitting flow and rev-ing it up will increase the flow but its still kind of erratic. I was told that as long as oil was returning to the tank it was OK but I'm not sure I'm getting enough volume through the engine. I know they're low pressure & low volume but the pressure dropping to 0 and the light staying on after it warms up just seems wrong to me. Its the original pump, and like I said when 1st starting up I get 32psi. and the light stays out, but once its at running temp. the light stays on & the pressure drops to 0. Is it really OK as long as some oil is returning to the tank? Or should there be a solid steady stream flowing into the tank?
Cotten
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Re: Oil Pressure & Flow

#2

Post by Cotten »

HP!

Return volume of any pump is always much higher than feed, because air must be returned as well.
That's why it doesn't seem constant. It burps.

Modern dashlight sending units can take anywhere from four to fourteen psi to operate, and yours sounds like a high one.
If its an Accel, you are lucky it works at all.

A stock pump still delivers and returns plenty of volume even below four psi.
It probably pumps its most volume when pressure is lowest, because that is when there is the least resistance.

It is resistance that builds pressure.
Falling gauge readings only reflect the warming of the motor, and take your eyes off the road, nothing more.

....Cotten
Hauula Pan
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Re: Oil Pressure & Flow

#3

Post by Hauula Pan »

Yeah the sending unit & pressure gauge are after-market which probably explains the light. Had this thing for 30 years now & this is the first time I ever had any of the indicator lights hooked up or had a pressure gauge installed. I guess ignorance was bliss before, I never had anything to warn me if something was going wrong & just fired it up & rode. Now I have all these indicators hooked up & get worried if they light up. So I guess you're saying that as long as I have oil returning to the tank I'm getting enough through the engine to keep everything oiled enough, and don't be concerned with the light & gauge?
NightShift
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Re: Oil Pressure & Flow

#4

Post by NightShift »

Dear Hauula Pan,
The light is still a good idea because even a crappy switch will warn you if something really bad happens suddenly after dark.

Respectf'ly,
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