WantACherokee

So I've been driving my '87 XJ around for a week or two now and it seems like it has good oil pressure at idle and when driving, and the gauge has always worked normally. The other day I was driving along when I noticed my oil gauge wasn't reading at all. It was all the way at zero and not even moving yet the Jeep was running fine. I figured it was just a sender/gauge issue so I ignored it. Then yesterday I start it up in the morning and see the gauge reading just under 40 at idle. As I pulled out of the driveway and headed down the street I watched it drop to around 20 and stay there until I stopped at a light, when it went back up to near 40 again. I've driven the Jeep for 2 days now and it's consistently doing this.

Any ideas what could be going on? I don't know if this is a bad sender, bad gauge, or a wiring issue, or if something weird really is going on with my oil pressure. I've never heard of oil pressure reading higher at idle than at higher RPM, so I don't know what to make of it. It doesn't seem to vary much at all based on specific RPM, it just reads right under 40 psi idling, and right at 20 anywhere above idle. Engine still seems to run fine, doesn't run warm or anything like that.

I figured I would try a new sender as a cheap and easy way to see if the sender is the problem, but it may be a day or two before I can do that. Do you guys think it's just a sender/gauge issue or might there actually be something wrong with the oil pressure? Should I not drive the Jeep until I pinpoint the problem?

TrekkerJmm

Sounds like the sender or a loose wire going to the sender. Its not Ticking/Knocking right?...Tj

WantACherokee

Forgot to add it did start marking a weird ticking noise when the gauge was reading 0, but it went away after a minute, basically by the time I could pull over safely it stopped. It sounded like it was coming from the valvetrain... I definitely thought my engine was messed up for a second, but then it just went away, and it continued running normal before/during/after making the noise.

WantACherokee

Anyone have any input? I am nervous to drive the Jeep with the gauge acting weird but I wouldn't think an oil pump would be something that would act up intermittently.

VTJeep

check all fluids!

WantACherokee

Oil is clean and full... so is everything else.

Is it possible I could have some gunk clogging the pickup that's affecting oil pressure? Maybe that could explain why the pressure is OK at idle but only reads 20 psi at higher RPM?

I'm going to get ahold of a manual oil pressure gauge hopefully tomorrow so I can find out if there's any truth to what the factory gauge is showing. I don't wanna second guess myself on an oiling issue. The Jeep needs a rear main anyway, so if I need to pull the pan and possibly replace the pump so be it. I don't want to hurt the motor by driving it around on low oil pressure so I'm just gonna park it until I figure out what's going on.