Duramax Oil Pressure, Again

[HDguy]

I just scheduled an appointment to replace either my oil pressure gauge, sending unit, wiring between, or all of the above.

My 07 NBS GMC has had what I would consider low oil pressure from the time I bought it, used, a month ago. The dealership controller had been driving it from new, so I'm sure he didn't care/know that this could have been a concern. I mentioned it on the day I test drove it, and was assured by all that this was normal on the LMM motor, and so no worries.

Well, after buying the truck, this continued to bug me, so I pursued it further. A tech told me the current specs for LMM motors are 14 psi at hot idle, and 42 psi at 1800 rpm. My truck was running, according to the gauge, about 20 psi at hot idle, but only about 35 psi at 2000 rpm. I had the service manager drive it with me, and he verified the numbers I was seeing. The lead tech hooked up a scan tool to the truck, and not only saw that the gauge was 10 - 15 psi low as compared to the scan tool, but slower to respond to rpm changes.

This made me feel better than the alternative of a motor with low oil pressure having been driven for 8000 miles.

If anyone else is experiencing this same problem, this may be the the solution for you.

[Killerbee]

The lead tech hooked up a scan tool to the truck, and not only saw that the gauge was 10 - 15 psi low ...

 

how do you expect replacing a sender to fix the disparity? The sender is what was providing the correct information for the Tech 2 reading. If anything, it is a gauge issue.

[BlackSilver]

I agree with killerbee. The scan tool is showing good pressure, so the sender is fine. Replace the guage.

[SLESierra]

check the grounds for the display first to ensure they are not getting some sort of feedback....