Fluctuating oil pressure.....

[CumminsPuller]

My brother-n-law's Oil pressure is running at about 20psi at idle, while driving it it goes up to between 38-40psi... ... His truck is a the same as mine (see signature) except his is a 3500. My oil pressure is always between 40-43 psi. We have changed his sending unit several times, each time it seems to read correctly for a day maybe two, the last one we put in never read correctly at all. We bought a mechanical gauge and hooked it up and ran the line into the cab so we could monitor the pressure while driving. At idle, 40 psi, while driving down the road approximately 60 psi... ... ... ... Any ideas what to do next??????? Thanks in advance!!!!!!



Jason

 

[JTeague]

Low oil pressure readings

Were you using a Mopar sender or a parts store replacement? I have an 86 dodge that did the same thing when I installed a parts store replacement sender. A genuine MOPAR sender cured the problem. You might check the terminals on the connector to see if they fit tightly on the pins of the sending unit. If not the gauge might be suspect. Hope this helps.

 

[redram]

On mine, it was the sensor. Replaced it and did not fluctuate.



I did monitor with a mechanical gauge and DC may have an averaging algorithm to smooth out the electrical signal as the DC dash guage never would match the mechanical guage installed at the same pickup point. It varied even more when installed at the filter.



That was 50K + ago and all is still fine. I have a 96 3500 5 speed and usually see 43-45 psi at idle with a warm engine.



There is a bypass valve in both the oil filter and also one in the oil cooler (located behind the oil filter head in the block) and maybe one of these are stuck.



I tried changing oil, oil filters, different guages over a two week period and could not get the same oil pressure readings. I just gave up and live with the elctronic one in the dash now.