Cummins Celect 500 hp engine cuts back power

Does it have any codes in it? On and N14, at 1200 rpm, it should have to drop below 20 psi to derate, which ramps up to about 25 psi at 1800 rpm. The best thing to do is to get it hooked up to a computer and see what's going on for sure. If it does have a code for low oil pressure, you may just have a faulty sending unit. I believe the gauge on your truck in manual, the ECM may be seeing lower than the gauge.

Wouldn't hurt to check the piston cooler nozzles, they crack and cause a pressure drop. I've seen them blow right apart and really hurt oil pressure. Much easier and cheaper to change than an oil pump, especially when you're guessing. Low oil pressure is usually worn bearings, internal oil leak, pickup sucking air, etc. It is rarely a worn pump.

The first thing to do is pull the fault codes to see exactly what fault is causing the derate.

 

oil pressure sounds OK,,need to have your ECM codes checked,,something that helps,,some times you can reset your ECM by disconnecting and reconnecting tour batteries, look on your heads to see if there are oil leaks from the wires going thru the heads,,they are called pass thru connectors if you do that may be the cause,,N14 are great engines,,

 

I suggest a manual guage to measure accurate oil pressure.

I would also change oil filter, on a hunch it is collapsed.

Then drop pan if low pressure still there and check piston coolers as mentioned. While there, check bearings.

How many miles on truck?

 

On N14's, there's no need to drop the pan, they go in from the outside. You only have to drop the pan if one (or several) broke off and went inside. Personally, I don't think he really has low oil pressure, N14 run pretty low compared to most other engines. It's never a bad idea to verify with a manual gauge though, but he'd need it hook up to a computer to see what the ECM is reading to compare. The manual dash gauge doesn't mean anything to the ECM.