I think I might have just developed this issue myself.
'04 WJ Limited 4.7. This just started doing this this morning when I was getting ready to park at work.
On startup the oil pressure gauge needle moves to just above the middle of the gauge right where it belongs, but any time the engine idles down to around 500rpms (I also have a vacuum leak I have a part ordered for just hasn't been delivered) but any time the rpms get around 500 rpms the oil pressure gauge drops down to about half way then after 5 secs or so if I haven't put my foot back on the gas it will frequently drop all the way down to zero and hover around there. The "Check gauges" light will come on when it drops all the way down. There is no ticking, knocking, or anything else like the engine is not getting enough oil, just the gauge.
Oil level is good and I'm about due for an oil change but not over. And I'm running Penzzoil High Mileage 5w-30.
This scared the heck out of me today.....but you know, as long as I would keep the rpms above 500 it didn't do it.
So for you folks that have had this issue......On cold mornings did the oil pressure read fine until the engine reached operating temps? I cranked mine up this AM and pressure read fine. I ran it for about 10 minutes to let it warm up and the gauge stayed just above center the entire time. It probably didn't get up to full operating temp this AM, but it didn't start dropping pressure yesterday until I got to work (about a 25 mile drive). Also yesterday evening I climbed underneath and noticed a little oil leaking from around the filter, more of a seep than a leak actually.....but it looks like it's leaking from above the filter (where the sensor is) and is leaking down onto the filter and then slowly dripping off the bottom of the filter.
Lastly, this might be a dumb question....Is it the oil pressure sensor or the oil pressure sending unit? Just want to make sure I get the right part LOL
So to re-cap my issue;
oil pressure gauge drops to zero or below half way when the engine idles down to around 500 and is at normal operating temp. Giving it a little gas brings the needle back to normal but it goes back down when it idles down. Oil level is perfect, oil is due for a change but not over, using 5-30 penzoil high mileage. Pressure doesn't drop at all at normal hwy speeds. Only when engine idles down to around 500rpms.
I'm pretty sure based on the multitude of threads that it's going to be the sensor/sending unit, but I just want to ease my mind....I'm not driving it until I get it fixed.
LOL so does anyone know if there are 2 different socket sizes for the oil pressure sensor? My new (MOPAR) sensor is 1-1/16". So because I no longer have any of my tools after the fire I've got to buy them as I need them. Oh and I had so many tools.......However NOW I've just got a basic set of sockets and none of them are the deep sockets of course so I went and bought a brand new socket for the new part. But when I put that socket on the old part it doesn't fit......I messed with it but I don't want to round it off but it was a no-go.
I got mine fixed. As it turned out, the previous owner had tried to remove the old sensor at some point and rounded off the edges of the nut part of the sensor. I ended up having to use a set of needle nosed vice grips to get it out. Luckily (and in part due to extreme caution on my part LOL) I got the old sensor out and the rest took maybe 5 minutes to get in and started back up.
Thanks all for the help. It's a scary feeling to watch your oil pressure dip to zero and not know for sure if it really IS zero or if it is something else.
I got mine fixed. As it turned out, the previous owner had tried to remove the old sensor at some point and rounded off the edges of the nut part of the sensor. I ended up having to use a set of needle nosed vice grips to get it out. Luckily (and in part due to extreme caution on my part LOL) I got the old sensor out and the rest took maybe 5 minutes to get in and started back up. Thanks all for the help. It's a scary feeling to watch your oil pressure dip to zero and not know for sure if it really IS zero or if it is something else.
That's one tool I don't have. My regular vice grips were worn out, do I went to go buy some new ones. I was looking for the needle-nose vice grips, too, because I had a bolt, in a fog light, unscrew it self from the base when I tried to unscrew the nut off of it. My regular vice grips were too worn out to help and I sure could have used the needle-nose type. The bolt finally snapped and came out. It broke part of the part that holds the base, but not enough to affect it.
LOL Yeah the big vice grips were too big for me to be able to turn the sensor so I had to resort to the needle nose, and trust me I was sweating it if it was going to turn or not. BUT it was a brand new set and I got it nice and tight. I hate using those to do something like that especially being a piece that bolts into the block, but in this instance I wasn't going to get it out any other way.
I used to have just about any tool a non-professional mechanic would need....but that was about 3 years ago before the wildfire. Burnt down the house, the garage, the woodshop, and pretty much everything else except for my chicken coop and TWO chickens. 1 rooster and 1 hen. But everything else was gonzo. Sucks, but I live in the country amongst some pretty giant pine trees so it was always a threat.
mine went bad slowly over a period of 2 years and squirted oil when I touched it be for replacing it. It basically squirted oil all over the engine for 2 years and my gage eventually gave out. easy fix
bolt on new part
Had mine completely stop working for about two months. The ding from the light coming on is more annoying than anything. As long as youre not burning oil, your good. I went with the mopar part that everybody swears by, and it hasnt had any trouble.
Mine didn't exactly fail either...It just became much more intermittent between correct readings LOL
Also, mine was seeping oil. Just enough to have a drop on the bottom of the filter and some had dripped down slowly and started getting on my front end components that were directly underneath and behind. Not bad, just enough to annoy me and of course the funky oil pressure readings it gave right before I changed it.