Last month my oil pressure on my 96' dropped to zero and bounced back and forth for a while (usually around 2k rpm-under load). Since that trip it has been close to normal, but I replaced the sending unit yesterday to see if that was the problem. Now the oil pressure is low at idle and normal around 1k and above. It has never been low even at idle before now. Has anyone had oil pump problems? I know the best step now is to pull the sending unit and get a direct pressure reading, but it would be nice to be prepared for the worst. Any input would be great.

 

My gauge did the same thing once a couple months ago. I figured it was the sending unit as well, but just for fun, I simply disconnected it and cleaned the connections on the unit and the plug with a can of electrical contact cleaner and made sure(as you can) the two small pins were making good contact. Plugged it back in and haven't had a problem since(knocking on wood here...). The difference in pressure reading is probably just the difference in senders; you know there isn't much chance any two would read identical. If you want to fiddle with it, I'd suggest cleaning/inspecting the original sender and harness plug, and try re-installing it. You might have as good luck as mine, and get your old familiar pressure reading back!! Best part is, it doesn't cost anything but time/effort, bad part is, if it returns to normal you probably can't return the new one, right? Good luck, hope you straighten it out, certainly not good to show no oil pressure, and I'm like you; I hate to see something different in a gauge reading!!

 

I can see a loose wire issue or faulty sending unit giving me random readings, but the current unit is steady and responds to the rpm's. What is normal psi at idle, and under load?

 

as long as it stays around 40 your good

 

I agree w/clutch1, 40psi is a great reading to see! :-) What I meant by possibly cleaning re-installing your original unit is A: You may discover(albeit a little late) there was only a connection problem - as mine apparently was, and B: It would then probably return to the original pressure reading(whatever that was) and make you feel more relaxed, right? BTW, as the new unit is stable, what psi are you reading now compared to what it was? Just curious to know the diff, main thing is you do have a steady reading now vs zero, eh? :-)

 

The truck came from Canada so the gage reads 0-760 with 270 in the middle. The needle stays at center (270 +/- 10(?)) and only flux's at idle-which is new. It's a good call to clean the wires/ connection-I will do that. I also just found an other thread that said that Cummins has a new style sending unit to do away with the flux issues. I was just worried that the oil pump (or pickup) was either getting blocked or wearing out-but I haven't heard of that yet so- back to the weak link.

 

after a good pull mine will come down alittle left of center but with a little throttle it will shoot back up to where it was, same difference on the right of center as it was to the left of center.