Oil Pressure irregularities - sending unit or oil pump?

[mud4feet]

For the last month or so, my '03 TJ 4banger has been acting really funny. Intermittently, every time it slows to idle speed, the oil pressure reading drops to zero and all the buzzers, lights, and bells start sounding telling me to check gauges. If I rev it up to about 1200 rpm, the pressure gauge goes back to normal and everything's fine. Oil level shows full on the stick. It never does this when cold or warming up, and doesn't always do it once up to operating temperature. It's got me puzzled (and a bit worried). Does it sound like a bad pressure sending unit or is my oil pump showing signs of age?

There are no other symptoms - engine runs fine otherwise.

Thanx in advance for any help.

 

[SteelHeadz]

Hey there Bud!!.. If when the oil pressure drops to zero and the check gauges along with the chime turns on, with the absence of a knocking or rattling from the engine, i would suspect that the oil pressure sending unit is bad. If you want to be sure, install a remote oil pressure test gauge on a tee connector fitting where the sending unit is and monitor the oil pressure from the instrument cluster. when it goes to Zero, check the test gauge and see if its the same.

 

[Keith__C]

Change your oil and use something that is quality stay the hell away from Quaker State, Pennzoil and Mobil 5000 What you are experiencing are the polymers that cause oil to thicken as it heats up failing. I bet when you change your oil it will pour out like water. Remember 10W-30 is only a 10 weight oil and once the thickening polymers (which alot of manufacturers seem to be using less of) go away that is all your are left with. I use either Valvoline High Zinc or Castrol with a tablespoon of Lucas engine assembly lube--this adds quite a bit of Zinc into the formula which is a good thing as most oils today have lost Zinc from their formula as well--new new cars don't need it in the formula so the manufacturer won't even put it in them. You should be starting to see oils popping up that state for cars 2004 and older--these still have Zinc however most are shy'd away from because they are "generics" I had the EXACT same problem on my Intrepid when I ran Mobil 5000 and my 4-runner with Pennzoil. Switch to Castrol/lucas formula and problems are gone. I own to many damn cars