Oil pressure gauge question

[harkauto]

I'm wondering about my oil pressure gauge on my 2001 Dakota with a 4.7 engine. The gauge on my truck simply has a low and a high side with a hash mark on each side indicating the normal range.

When the truck reaches normal operating temperature the red needle always stays within the normal operating range. When I decelerate and slow for a stop sign the needle slowly moves down to and touches the normal range hash mark on the Low pressure side but never goes below the normal mark.

Then when I accelerate back up to traveling speed the needle then slowly rises up to and just touches the hash mark on the high side but again it never goes beyond the normal range.

The needle has this constant wide swing back and forth between low and high all the time I am driving but the needle never transgresses outside of the normal range and I'm wondering if this is normal, or do I possibly have a wonky oil pressure sending unit.

My friend has a GMC pick up and he has a similar oil gauge and the needle on his truck stands straight up in the normal range and never seems to move even slightly to the left or the right all the time his truck is running.

I'm wondering if this is the normal function for the 2001 Dakota oil pressure gauge.

Thanks!

Harkauto

[Scotty89]

It is normal to see some movement on the gauge but I don't think it should move from one end to the other. If this was mine I would find a mechanical pressure gauge and check my oil pressure and see if it is actually fluctuating that much and go from there. Oil pressure does fluctuate some when accelerating and stopping, but I have never seen one move from one end of the normal to the other. If the pressure is within spec. I don't think I would worry much about it. If it does have a oil pressure issue there is several things it could be.

1. Run engine until thermostat opens.
2. Oil Pressure:
   • Curb Idle—25 Kpa (4 psi) minimum
   • 3000 rpm—170 - 550 KPa (25 - 80 psi)

[harkauto]

Originally Posted by Scotty89

It is normal to see some movement on the gauge but I don't think it should move from one end to the other. If this was mine I would find a mechanical pressure gauge and check my oil pressure and see if it is actually fluctuating that much and go from there. Oil pressure does fluctuate some when accelerating and stopping, but I have never seen one move from one end of the normal to the other. If the pressure is within spec. I don't think I would worry much about it. If it does have a oil pressure issue there is several things it could be.

1. Run engine until thermostat opens.
2. Oil Pressure:
   • Curb Idle—25 Kpa (4 psi) minimum
   • 3000 rpm—170 - 550 KPa (25 - 80 psi)

Thanks Scotty! Does the mechanical pressure gauge install where the oil pressure sending unit connects?

Could my dash gauge be reading like it does because the Oil pressure sending unit may be faulty?

I'm not seeing any oil pressure warning lights on the dash at all. At start up the oil light comes on along with the other dash lights and then immediately goes out when the engine starts which I think is normal.

[Scotty89]

Yes the gauge will connect where the sending unit is and it could be a faulty sensor. All the ones I have seen quit reading completely but that doesn't mean the sensor can't be it. What you may do for a quick check is unplug the sensor and make sure it isn't leaking into the connector. Inside the sending unit is basically a rubber diaphragm that moves back and forth and over time they can split and leak. The lights come on for a bulb check and then go out when first turning on the key. The warning light probably won't come on til the gauge leaves the normal area.