Low oil pressure / inconsitant oil pressure

GlennLever wrote:
I'm a little concerned.

This is a 6CTA, Ref # 53-34874-004 engine # 45358278, model C8.3-325, read that as 325 HP.

When first cranked (weather cold -12, or hot 110) the oil pressure gauge on the dash pegs (all the way to the right, in the white above the green, not pressure indicated on the dash gauge, just red, green, white)

When fully warmed up and running at 1500 RPM about 55 MPH, it will sink to within 1/8 inch of the line between the red and green, never goes into the red (going down the road).

When idling it does fall into the red, but as soon as you accelerate away from a stop light it immediately climbs into the green.

If you bring the RPMs up to 1500 when sitting with no load and fully warm it pegs the top of the green.

When going down hill and at 1500 rpm it pegs the needle to the top of the white.

Low oil pressure warning only comes on before cranking and never while running.

I have it at a Cummins authorized shop right now. They have have explained there are two oil pressure sensors, one for the computer, and one for the dash gauge. They will be putting it on their computer to see what that says.

There are several entries on this when you do a google, but no resolutions offered, just a post describing sort of the same thing.

I have driven this from AZ to NY, Ny to NH and back, NY to Ky and back, and it has acted like this consistently. Chassis voltage is at 14 volts all the time when running.

Thoughts?

I have heard back from the shop, they could not put a computer on the engine because of the age, but did put a mechanical gauge on the engine and say it is "operating normally" what ever that is.

Although my gage is numbered I see pretty much the same levels that you describe. When first starting up cold a pressure of 70-80 is noted depending on ambient temperature. Now, 70-80 I would estimate is in the upper portion of that white area you describe. When fully warmed up and idling I run 15-25, again in the red-green area you describe. When fully warmed up and running down the road or climbing hills 40-50 or in the green you describe. On gentle downhill, I have noted a climbing pressure because, I think, the engine is under no or little load and the cooling system is able to reduce the engine oil temperature some and therefore increase oil pressure.

Bottom line, I think yours runs normally.