The Ford Barn

B_man_Al · 01-22-2012, 06:32 AM

Anyone have any ideas why my oil pressure guage (installed on the block) is very erratic ( bouncing up and down about 10 PSI ) around 40 -50 PSI.

Could this be the oil pump release valve cutting in and out? Its a new pump.

Al

Zeke...PA · 01-22-2012, 07:23 AM

It could be the gauge. Zeke

ford1 · 01-22-2012, 07:59 AM

there is supposed to be a brass sleeve or button in the oil line right at the gauge, it has a very small hole in it to slow down the flucation of the needle, the small hole doesnt let the pressure bleed off quickly and let the needle bounce around

G.M. · 01-22-2012, 08:20 AM

Grainger has the dampers or snubbers as they are called. They come with pipe theads, male one end and female in the other. I use oil filled gauges that eliminate the fluculations. I don't think the relief would fluctuate, but it's possible. The ones I saw on a tester would hold the pressure for a while and slowly leak down to a low pressure. When shut down and restarted they would come up to pressure and start to leak again. There was no set time from when they worked good until they started leaking. G.M.

jdl · 01-22-2012, 09:03 AM

Is this a newly rebuilt engine? you do need the orfice in the gauge line as others have said, But it can also be a slightly bent crankshaft causing the fluxuating needle, your engine will also be a little noisy kind of like a diesel.
I know first hand about this as I had a it happen to me, so I hope it is just your gauge.

B_man_Al · 01-22-2012, 03:16 PM

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Thanks for the inputs , I'll look at the guage first. Its an old well pump guage 0-100 PSI which already has an orfice at its input. Probably about 1/8" in dia but I haven't measured it. How small are the ones you guys refer to?

Yes the engine is a new rebuild, running on a stand. The crank has been turned so I think its OK.

Al

columbiA · 01-22-2012, 07:25 PM

The orifice for the guage is very small,maybe .020 or so.If its 1/8" then thats likely why the guage fluctuates.

ford1 · 01-22-2012, 09:25 PM

1/8" orfice is the size of the oil line going to gauge, way to big, .020 or smaller is what you need, stop by your car parts store and ask if you can look at the size orfice that is in an oil gauge kit, then get one that size

paleot · 02-01-2012, 03:19 AM

Mine does the exact same thing,I used a 100 psi gauge with no orfice.Fresh rebuild and new pump.
Tony

01-22-2012, 06:32 AM	#1
B_man_Al Senior Member Join Date: Feb 2011 Location: Ottawa ON Canada Posts: 301	8BA Erratic Oil Pressure Anyone have any ideas why my oil pressure guage (installed on the block) is very erratic ( bouncing up and down about 10 PSI ) around 40 -50 PSI. Could this be the oil pump release valve cutting in and out? Its a new pump. Al

01-22-2012, 07:23 AM	#2
Zeke...PA Senior Member Join Date: May 2010 Location: Delta, PA Posts: 525	Re: 8BA Erratic Oil Pressure It could be the gauge. Zeke __________________ Only problem with retirement is never a day off

01-22-2012, 07:59 AM	#3
ford1 Senior Member Join Date: May 2010 Location: oroville ca. Posts: 1,554	Re: 8BA Erratic Oil Pressure there is supposed to be a brass sleeve or button in the oil line right at the gauge, it has a very small hole in it to slow down the flucation of the needle, the small hole doesnt let the pressure bleed off quickly and let the needle bounce around

01-22-2012, 08:20 AM	#4
G.M. Senior Member Join Date: May 2010 Location: Florida and Penna. Posts: 4,471	Re: 8BA Erratic Oil Pressure Grainger has the dampers or snubbers as they are called. They come with pipe theads, male one end and female in the other. I use oil filled gauges that eliminate the fluculations. I don't think the relief would fluctuate, but it's possible. The ones I saw on a tester would hold the pressure for a while and slowly leak down to a low pressure. When shut down and restarted they would come up to pressure and start to leak again. There was no set time from when they worked good until they started leaking. G.M. __________________ www.fordcollector.com

01-22-2012, 09:03 AM	#5
jdl Senior Member Join Date: May 2010 Location: California Central Coast Posts: 931	Re: 8BA Erratic Oil Pressure Is this a newly rebuilt engine? you do need the orfice in the gauge line as others have said, But it can also be a slightly bent crankshaft causing the fluxuating needle, your engine will also be a little noisy kind of like a diesel. I know first hand about this as I had a it happen to me, so I hope it is just your gauge.

01-22-2012, 03:16 PM	#6
B_man_Al Senior Member Join Date: Feb 2011 Location: Ottawa ON Canada Posts: 301	Re: 8BA Erratic Oil Pressure Sponsored Links (Register now to hide all advertisements) Thanks for the inputs , I'll look at the guage first. Its an old well pump guage 0-100 PSI which already has an orfice at its input. Probably about 1/8" in dia but I haven't measured it. How small are the ones you guys refer to? Yes the engine is a new rebuild, running on a stand. The crank has been turned so I think its OK. Al

01-22-2012, 07:25 PM	#7
columbiA Senior Member Join Date: Nov 2011 Location: B.C. Canada Posts: 1,746	Re: 8BA Erratic Oil Pressure The orifice for the guage is very small,maybe .020 or so.If its 1/8" then thats likely why the guage fluctuates.

01-22-2012, 09:25 PM	#8
ford1 Senior Member Join Date: May 2010 Location: oroville ca. Posts: 1,554	Re: 8BA Erratic Oil Pressure 1/8" orfice is the size of the oil line going to gauge, way to big, .020 or smaller is what you need, stop by your car parts store and ask if you can look at the size orfice that is in an oil gauge kit, then get one that size Last edited by ford1; 01-22-2012 at 09:33 PM.

02-01-2012, 03:19 AM	#9
paleot Senior Member Join Date: Jan 2012 Location: s/w Louisiana Posts: 119	Re: 8BA Erratic Oil Pressure Mine does the exact same thing,I used a 100 psi gauge with no orfice.Fresh rebuild and new pump. Tony