Oil Pressure gauge up n down

[brushwoodnursery]

2000 explorer, 160K miles Limited package. overdue for an oil change, not driven much (can go 3 days w/o driving, then just errands). Oil pressure gauge died a few years ago. replaced unit at engine and all was fine. I think I got help here for that!
This time, drove about 15 minutes to town and the gauge started clicking up and down at idle. Came on fine while revving or driving. 2 hours later, drove home and all was fine until almost home and the same symptoms. Fine with even a little gas but clicks off at idle. (I know it isn't really displaying a specific pressure and it's an on/off display).
Oil level looks good. Oil is dirty but not gummy or milky.
Trouble? Maybe just an oil change with cleaner needed? (never done the cleaner thing) Your thoughts?

 

[yavapaires]

Install a mechanical gauge before you get carried away worrying about what is going on, then you have a better diagnosis. If you havechanged the sender before, you can install a gauge. IMHO, it is probably a loose connection at the sending unit, especially if there is no engine noise such as valve clatter, or knocking.

 

[koda2000]

sounds like a bad connection at the sender, or the wire to the sender may be worn and grounding out on something, or another bad sending unit.

i'd guess the sending unit as you say it seems to work normally at higher RPM/oil pressure, which would also be the case when the engine/oil is cold.

changing your oil (although a good idea) probably won't help this problem.

 

[SoNic67]

Don't you hear noises in the engine compartment while at idle? I think you have low oil pressure at low rpm and with the warm oil (thinner). The sender is just a switch - below 5psi it shows "zero", past 5psi shows "ok". Your pressure fluctuates (at idle) around the 5psi value. Lifters are the first to start "chatter" with 5psi.
Put the transmission in N at stoplights and you will see that improves. Use 5W-40 oil (Shell Rotella).
Maybe new oil pump? That's expensive labor!

 

[brushwoodnursery]

Sounds and drives just fine. Well, that is, there seems to be no change. I'll look at a manual gauge and see about loose wires where possible. Thanks!

 

[SoNic67]

You can install in place of the sender a mechanical oil gauge. I did it on mine for testing purpose - the small hose will fit on side of hood and closed driver door so you can have the gauge on dashboard.