warm oil

[jaredssc17]

when my motor heats up and im at idle some times the idle drops about 800-700 rpms and the oil pres. starts jumping around. the needle bounces to 0 the up to norm. this happens really fast. the ck gauge light comes on. as soon as i bring up the rpms it stops ne ideas?

 

[Bob Ayers]

Try changing the oil pressure sending unit. This is a normally open switch, that closes with about 7PSI of oil pressure, which causes the gauge to read about half-scale. It is not a true oil pressure. So, the gauge reads no oil pressure, or half-scale, and that's why the gauge is bouncing.

 

[Wicked_Sludge]

like bob said, your oil pressure "gauge" is no more than a aesthetically pleasing idiot light. however, it sounds to me like your oil pressure may be on the ragged edge at idle (opening and closing the switch, causing the needle to bounce), and revving the motor increases the pressure enough to hold the switch closed. the fact that it only occurs at idle and when warm just reinforces this theory.

before replacing the switch, i would verify (or have verified) the oil pressure at warm idle to see if it is is actually the switch, or if you indeed have low oil pressure.

 

[LegacyL22]

i hate to say it, but it sounds exactly like what mines doing right now...deffinately hook up a mechanical gauge to see what its really doing .
http://www.therangerstation.com/forums/showthread.php?t=15253 thats the address for my post...it might help you out a little bit, and if you have any questions about how to hook up a mechanical gauge, just reply in this thread...by the way, on my 4.0 the pressure sensor gauge is on the drivers side of the engine...if you lie down with your head next to the drivers side front wheel, you should see it...it sticks out with a single wire, and a white harness. Good Luck.