Engine Oil Pressure

[Manu Mach1]

Hello,

On my Grandé, originally there is not the 3 gauges (homemade), oil pressure, amp, water temp.

Now there are 3 gauges, oil temp, oil pressure, water temps.

1 bar equal 14 psi.

About the oil pression, the gauge (0-10 bars) is connected to a sender unit, 0-5 bars (72 psi).

When I start, cold engine, I get 126 psi at throttle. Then when engine is warm, I get around 4 bars, so around 60 psi.

I change the oil, from 20w50 to 15w40, a small change but still high pressure.

What I want to do is to connect an hydraulic manometer direct on to the engine and read.

Any idea?

 

[midlife]

The oil pressure at cold start-up is higher due to the cold temperatures. As temperatures rise, the pressure decreases. Sound pretty normal to me.

 

[mustang7173]

manu64,

Is the pressure sending unit electrical? If so, then a mechanical sending unit would be in order and maybe a pressure gauge from a source like http://www.mscdirect.com/browse/?navid=12108019+4288211857. At least with a mechanical gauge, this would help determine the accuracy of your electrical gauge and relieve worries of other problems with your oil pressure.

midlife's response is right on.

All, correct if I wrong on this, since the engine is cold, 20w would Not flow as quickly as with 10w? I believe the both numbers are important less wear at start-up and protection after engine warms up!

mustang7173

 

[Manu Mach1]

This is an 5 bars electrical sending unit, so first how is possible this one send 9 bars to the manometer?

Then I read that the normal pressure for the 351 C is between 35 and 60 psi, it's why I'm surprised to get so much pressure.

 

[Don C]

It may be called a 5 bar because that is the accuracy limit, and becomes inaccurate at higher pressures.

The pressure relief spring in your oil pump may be stuck closed or has too many shims against the spring.

 

[Jeff73Mach1]

I think your gauge and sender are not compatible. I suspect your pressures are not as high as that.

 

[Manu Mach1]

Probably 5 bars sender unit need to be installed with 5 bars manometer, same for the 10 bars models.

Anyway, I will test the pressure with a hydraulic manometer.

 

[Manu Mach1]

Probably 5 bars sender unit need to be installed with 5 bars manometer, same for the 10 bars models.

Anyway, I will test the pressure with a hydraulic manometer.

So I test with a Barflex box, and at idle with engine cold:

4.7 bars= 68 psi.

This looks more normal than 9 bars I read before on my manometer

 

[marks73]

This is why I'm not a big fan of electrical sending units. You need to be sure the range matches the gauge. (something they typically don't tell you when you buy)

 

[Manu Mach1]

I received the sender unit 0-10 bars, and now it's fine.

Weather is bad at the moment, but tomorrow if possible I would like to warm up the engine to check the pressure at hot temperature.