Oil Pressure low? Help appreciated

bnold

Cummins. What else?
Joined
Jul 13, 2007
Messages
140
OK recently installed an ISSPRO EV oil pressure gauge... electric sender

Was suprised to see how low my oil pressure was when hot at idle... Have to figure out exactly what each tick means between 20psi and 0psi (weird spacing here) but I would imagine the gauge shows oil psi to be 10ish??... at 750rpm.. go 800rpm and it is at 20psi cruise 2000rpm 35psi... This is all hot, cool the motor runs much higher, normal.


The FSM is unclear about min oil pressure at idle hot, one place says 10psi min another 15psi min, and the idiot light doesn't come on until under 6.5psi

My stock OP gauge reads a few needle widths below 40psi at idle and about 40psi at cruise... I know some say the oil pressure gauge is just a glorified idiot light, but the FSM differs..
"Each time
the cluster receives a message from the PCM indicating
the engine oil pressure is between about 6.9 kPa
(1 psi) and 137.9 kPa (20 psi) for gasoline engines, or
55 kPa (8 psi) and 58.6 kPa (8.5 psi) for diesel
engines, the cluster holds the gauge needle at a point
about 11 degrees above the low end of normal increment
on the gauge scale. Each time the cluster
receives a message from the PCM indicating the
engine oil pressure is between about 517.1 kPa (75
psi) and 755 kPa (109.5 psi) for gasoline engines, or
551.6 kPa (80 psi) and 755 kPa (109.5 psi) for diesel
engines, the cluster holds the gauge needle at a point
about 7.4 degrees below the high end of normal
increment on the gauge scale. When the cluster
receives messages from the PCM indicating the
engine oil pressure is between about 137.9 kPa (20
psi) and 517.1 kPa (75 psi) for gasoline engines, or
58.6 kPa (8.5 psi) and 551.6 kPa (80 psi) for diesel
engines], the gauge needle is moved to the actual
pressure position on the gauge scale."





Motor should be in good shape, highly doubt I have high enough bearing wear to lead to poor oil pressure... Oil analysis sure dont point that way either...

Ideas:
-I'm not teed off of the vac pump line but rather using the port behind that for an oil , also I do not have a restrictor in the line just a straight -4 hose. (restrictor on the back side of the pump correct? I'm using the front side with no restrictor)
-Twins so using that extra feed line for my bottom turbo
-ISSPRO sending unit plugged into the port even further back on the motor, behind where the IP is getting its oil feed, the ECM was originally covering this hole, had an 1/8" NPT allen plug (is this an ok place for oil pressure? assuming that galley is common for all feed lines and stock OP sending unit? am I wrong?)

Could it be a combination of the above?

Up for ideas? really think my OP shouldn't be that low... and a tad of RPM brings it up to 20 in a heartbeat
 
My ISSPRO oil psi gauge read about 15-20 at idle when hot, 35-40 running down the road.
 
The first time I used an electronic oil pressure mine read 80-90 cold at idle depending on outside temp and a minimum of 40 when hot at idle. After about a week, the oil pressure sending unit would read 8-10 at idle.

I swapped it out for a mechanical oil pressure gauge and it reports 80-90 cold and 40 hot at idle again. Maybe it's my old age, but I don't trust oil pressure to an electronic sender.
 
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