1992 dodge cummins 12v intercooled 5 speed 4x4 154k miles. At start up low oil pressure light comes on and goes off as it is supposed to. After a long drive and motor is up to temp when you stop and let motor idle low oil pressure light will come on again. If you apply just a smidgen of throttle then light goes out.

As a stop gap measure I tightened up throttle shaft slack and that raised idle approx 100-150rpm. No oil pressure light issues now.

Oil pressure gauge sometimes will show a little (10% of scale) pressure while accelerating at full throttle. Otherwise nothing. Driving around with 0-5% pressure is disturbing at best.

Fresh oil change w/15w40 shell rotella.

Vehicle was previously owned by a shyster/fool/idiot. ANYTHING wierd imaginable is possible. Previuois owner replaced front clip with front clip off of 90'pickup and I have wires and crap everywhere that is not reattached correctly or properly. Have a wire going to back of fuel pump with spade connector that doesn't fit right. Not sure of wire's purpose.

Possible gauge/sender issue for oil pressure?

Where is oil pressure sender?

Where is oil pump?

All work has to be done in street in front of house. Do I need to send to shop?
Anyone know a knowledgable 5.9 first gen guy in western Kansas?

 

how much oil is in the truck and when was the last oil change?

 

Fresh oil change shell rotella t 15x-40 16or 17 quarts I believe. 4 gallons and 1 quart? Same issue pre and post oil change

 

Sorry, I just seen this - its the sender. Get a newone from Cummins (not a parts store - they dont last) and everything will be good again.

Sorry, I looked it up but couldnt find a p/n for you.


The sensor "should" be on the drivers side of the block behind the power steering pump:

 

Thanks Very much! I Thought that was the sending unit. Nice to know for sure... Have a great day!

 

Well, 98% chance that its the sender. Oil pumps can fail on these but its not all that common.

 

There's a good chance that the low idle is actually causing low oil pressure; when the injection pumps get too old, they cause the low-idle when they get warm, and low idle on an older engine does cause low pressure.

Probably won't hurt anything, but the light is probably doing its job.

The solution is to bump up the idle.

Do you know what RPM it's idling at cold and what RPM it's idling at when it's showing the light?