Oil Pressure Idiot Gauge- what is the scale?

[almostblue]

Mercruiser 260 - came with a gauge with a no label scale - was wondering if it is a linear scale, and perhaps it is 0-80, with 40 psi straight up. I know I can replace it or just use a voltmeter, but it would be nice to no what PSI my engine is hitting at idle when it graces the white strips on the left. I believe it is hitting 10 psi at idle (the very light portion of the progressively shaded white area) , and not getting back up to 20 psi until 2000 rpm, and 40 psi at 2500 rpm and above - all just speculation. It might be nice data to capture via a computer input, but it aint rocket science. I am getting 42 knots and 4200 RPM at WOT, btw.

attached image extracted from a much larger photo - I will need to retake a photo

 

[Bondo]

Re: Oil Pressure Idiot Guage- what is the scale?

Re: Oil Pressure Idiot Guage- what is the scale?

Ayuh,... Hey, it's a Abunch Better than an Idiot Light,+ buzzer....
It don't really matter anyways,... If it's runnin',+ Not knockin',... She's Good to Go....

Many Motorheads, who really whata Know the Actual #s,...
Mount a mechanical gauge directly to the motor....

 

[havasuboatman]

Re: Oil Pressure Idiot Guage- what is the scale?

Re: Oil Pressure Idiot Guage- what is the scale?

I don't completely agree with Bond-o on this one.
Better than an idiot light and buzzer. Yes.
But as long as it ain't knocking and you are good to go? Yikes!
If I only have one gauge on my dash that's working, Aside form temp, I want it to be my OP gauge.
The first sign of internal mechanical failier is dropping oil pressure.
If you really are only running 10 psi at idle, your oil pressure is too low.
Also, while nearly all electronic OP guages use Ohm veriance to activate the needle on the gauge, not all gauges use the same Ohm range. That could be the only reason your gauge is reading so low.
Did you just aquire this boat?

 

[mkast]

Re: Oil Pressure Idiot Guage- what is the scale?

Re: Oil Pressure Idiot Guage- what is the scale?

If you really are only running 10 psi at idle, your oil pressure is too low.

According to Mercruiser:
Oil pressure @ 2,000 RPM 30-55 psi.
Min. oil pressure @ idle 4 psi.

 

[JustJason]

Re: Oil Pressure Idiot Guage- what is the scale?

Re: Oil Pressure Idiot Guage- what is the scale?

Rule of thumb is 10psi for every 1000 rpm and your good to go.

 

[almostblue]

Re: Oil Pressure Idiot Guage- what is the scale?

Re: Oil Pressure Idiot Guage- what is the scale?

thank you for all of the responses. I will hook up a meter for academic purposes.
I assume the oil pressure is regulated at a certain PSI - perhaps 40 psi.. the guage would then tell me if the regulator is failing as well. Based on interpolation, it looks like I am getting 15-18 at idle. and up to 40 pretty rapidly.

 

[mkast]

Re: Oil Pressure Idiot Guage- what is the scale?

Re: Oil Pressure Idiot Guage- what is the scale?

I assume the oil pressure is regulated at a certain PSI - perhaps 40 psi.. the guage would then tell me if the regulator is failing as well.

The lubrication system uses relief springs to dump excessive pressure.
The condition of the bearings will control the oil pressure, there is no regulator.

 

[almostblue]

Re: Oil Pressure Idiot Guage- what is the scale?

Re: Oil Pressure Idiot Guage- what is the scale?

The lubrication system uses relief springs to dump excessive pressure.
The condition of the bearings will control the oil pressure, there is no regulator.

I see... they often call it a oil pressure regulator when it called a "pressure regulating valve" (with a spring as you mention), so I think "pressure reief valve" is more accurate. I didn't know the filter had relief valve.

 

[elkhunter338]

Re: Oil Pressure Idiot Guage- what is the scale?

Re: Oil Pressure Idiot Guage- what is the scale?

You need to check oil pressure with a mechanical gauge, then mark on your gauge the oil pressure. the electric gauge you have gives you no idea at all, you might not even have a sender unit calibrated for your gauge.
My temp gauge in my boat reads 220 deg. not true the engine is running 160.
My electric oil gauge had a sender going bad so I removed the gauge and installed a gas fumes detector alarm in its place.

I installed a set of mechanical gauges near the engine both oil pressure and water temp. I can glance at these while driving the boat if I want to turn around. Or when fishing they are right in view. I used all plastic gauges to avoid rust
I installed a high water temp alarm and light and a low oil pressure alarm and light. Both water/oil warning use the same light and buzzer. Oil pressure is a 10 or 15 psi min switch and the high water temp I think is 190 or 200.
I used a electric fan switch for automotive use that comes on at 190deg. to turn an electric fan on.

 

[almostblue]

Re: Oil Pressure Idiot Guage- what is the scale?

Re: Oil Pressure Idiot Guage- what is the scale?

You need to check oil pressure with a mechanical gauge, then mark on your gauge the oil pressure. the electric gauge you have gives you no idea at all, you might not even have a sender unit calibrated for your gauge.
My temp gauge in my boat reads 220 deg. not true the engine is running 160.
My electric oil gauge had a sender going bad so I removed the gauge and installed a gas fumes detector alarm in its place.

I installed a set of mechanical gauges near the engine both oil pressure and water temp. I can glance at these while driving the boat if I want to turn around. Or when fishing they are right in view. I used all plastic gauges to avoid rust
I installed a high water temp alarm and light and a low oil pressure alarm and light. Both water/oil warning use the same light and buzzer. Oil pressure is a 10 or 15 psi min switch and the high water temp I think is 190 or 200.
I used a electric fan switch for automotive use that comes on at 190deg. to turn an electric fan on.

I like it. Thank You. I think I will try to find a T fitting for the sender to install a mechanical gauge in parallel.. any recommendations?

 

[almostblue]

Re: Oil Pressure Idiot Gauge- what is the scale?

attached photo of better quality

 

[Ridemywideglide]

Re: Oil Pressure Idiot Guage- what is the scale?

Re: Oil Pressure Idiot Guage- what is the scale?

I like it. Thank You. I think I will try to find a T fitting for the sender to install a mechanical gauge in parallel.. any recommendations?

You won't need T fitting.. You'll either replace the existing sender unit, or you'll find another hole in the block to use for the mechanical guage.

 

[Bondo]

Re: Oil Pressure Idiot Gauge- what is the scale?

You'll either replace the existing sender unit, or you'll find another hole in the block to use for the mechanical guage.

Ayuh,... WHY,..??