Manual Oil Pressure Gauge Reading

[Chief Brody]

I've had so many issues with original gauges lately, I figured I might as well round it out with this.

My original manual oil pressure gauge is reading high in the Blazer. When I gun it it is reading 60. I don't necessarily believe. I thought it was because I went from 10W30 to 10W40, but it wasn't because I went back to 10W30 and same thing.
It is the original gauge in the 1974 Blazer.

Looks like this:

 

[Fastereddie]

My factory gauge is the electric one but it goes past 60 under any rpm untill it’s totally hot.

 

[sweetk30]

@Fastereddie the early days these trucks got mech oil pressure with the copper tube to the engine .

i would get a good QUALITY mech gauge and test it to what yours shows . this will pin point the gauge or other problem .

us electric guys can cheet tho . 6.2 gauge and sender get you 80 psi . c40-up stuff you can find 100 psi units .

my under 2k mile gm new engine 350 vortec has 5w-30 mobil 1 full synthetic and she does around 60 psi a lot . i should try a new sender but if i do it will be the 80 psi unit and i will swap the gauge with a 80 psi i have .

 

[Fastereddie]

Does your engine have a high pressure oil pump?

 

[Fastereddie]

@Fastereddie the early days these trucks got mech oil pressure with the copper tube to the engine .

i would get a good QUALITY mech gauge and test it to what yours shows . this will pin point the gauge or other problem .

us electric guys can cheet tho . 6.2 gauge and sender get you 80 psi . c40-up stuff you can find 100 psi units .

my under 2k mile gm new engine 350 vortec has 5w-30 mobil 1 full synthetic and she does around 60 psi a lot . i should try a new sender but if i do it will be the 80 psi unit and i will swap the gauge with a 80 psi i have .

Oh yeah, I’m aware of the mechanical gauges. My first blazer was a ‘73. I was just trying to say that mech or elec, 60 psi is not uncommon in the trucks I’ve had.

 

[blazer74]

Mine reads 60 cold due to a high volume pump.

 

[Chief Brody]

Is 60 bad on a 1975 350 small block? I don't know if I have a high pressure oil pump...I kind of doubt it. This was a crate motor...but the previous owner could have put a high pressure in...I just wondered if oil pressure gauges go bad...and when they do, do they lean towards weak oil pressure or high?

 

[Fastereddie]

Nothing wrong with 60. Hell, my work truck hits a touch over 80 when cold. On a mechanical gauge, the oil pressure causes a coil to try and unravel. I would “guess” if the copper coil was fatigued, it may read higher than actual.

 

[blazer74]

Just puts addition stress on the camshaft oil pump drive gear. PBA.

 

[sweetk30]

scott aka 4x4high told me years ago sbc and bbc unless crazy work is done only need std production pump installed . he seen lots of motors die from high volume and pressure sucking the pan dry cause the engine was not setup correctly and they didnt need it anyway .

 

[Fastereddie]

 

[blazer74]

Never had a problem, later was told it’s not needed

 

[dyeager535]

You said "gun it", but what does it read at cold idle and warm idle? Normally that is where you will see the most variation.

It's common for pressure to rise somewhat as the RPM's increase.

60 would be uncommonly high for a stock oil pump. Nothing wrong with a pump in there that will produce that, just not what the stock pumps pushed.

 

[Chief Brody]

You said "gun it", but what does it read at cold idle and warm idle? Normally that is where you will see the most variation.

It's common for pressure to rise somewhat as the RPM's increase.

60 would be uncommonly high for a stock oil pump. Nothing wrong with a pump in there that will produce that, just not what the stock pumps pushed.

honestly, it seems all over the place. I've seen it low I've seen it high...i saw it go wacky for a second. By gun it, I mean floor the accelerator...sometimes it idles around 30 if the gauge is correct. If I floor it it goes to 60. Once I saw it go to maybe 10...I will say this...the motor is running better than it ever has.