I have a 99 318 with 104k my oil psi gauge drops and my checkgage light comes on for about a second or 2 and the oil pressure goes back up. it drops like it has lost power real fast not like it gets low and lower till it comes on. the gauge reads about 35 and stays there use to move around with more rpms now comes up and stays there tills it drops.Do you think it is the gauge or the pump? when it drops there is no engine noise change. confused..... also only does this at low rpms. running down the road it stays in one place runing 30 or 80.

 

it could be the pump other then that it could be the bearings but with 104 it shouldnt be the bearings

 

something i read in the service manual.. somewhere along the way dodge changed the oil pressure gauge to not always directly display the actual psi at every point in time. instead the pcm reads the pressure from the sending unit, and then positions the gauge where it feels like it. i don't know what year that was.

its probably not the gauge, as it is controlled by the pcm. you can do a gauge test with the trip meter pressed and held when turning key to on.
could your fast drop be your sending unit ?

 

It never hurts to check the pressure with a real gauge at the sending unit hole. Would rule out the pump if it reads good. It might be a pain though because, IIRC, the sending unit is located back by the distributer.

 

You should eliminate the fact that there actually is an oil pressure problem first. You'll have to unscrew the oil pressure sending unit (a can threaded into the back of the block to the passenger side of the distributor) and replace it with a mechanical unit. I run enough line to go through my firewall and into the truck so I could monitor it while I drove........ If the mechanical gauge does it, you got engine problems. If the mechanical gauge DON'T do it, you have electrical problems............ mech gauges are cheap.

It'll cost about $20 and 1 hour of laying on the engine feeling the back of the block. Yay.

Oh, and your check engine light will come on when you start the truck because as far as the truck is concerned..... you no longer have oil pressure.

 

It was the sending unit thanks all of you.