smtippin

Hey all, my stock pressure sensor (yes I know the lack of reliability iwth the stock oil pressure sensor) is tripping out.

I have always read a steady 60 when driving. I'd range from 40-60 without ever fluctuating or going above of below it. Suddenly, when driving today (first time on the freeway in a while), my gauge started reading high (like over 80 for sure) and ended up bouncing back between 40 and 80+. I don't get it. Sure I just put a lift on, but we didn't touch the engine at all. The oil was changed 1000 miles ago.

What is going on? What could this be?

Thanks,
s

Dan4governor

subscribed. I'm having the same problem.

5-90

Replace the sensor, it's probably getting fluky on you. I've seen them do that before failing altogether plenty of times...

What's happening is that there is a diaphragm in the pressure sensor rigged to a variable resistance, and this variable resistance starts to develop "flat spots" on the track - just like the TPS does (and other carbon-track-wiper variable resistances) and needs to be replaced, even if they're not leaking.

Make sure to check that you don't have any wiring faults while you're about it, and clean everything up anyhow.

Dan4governor

K, I know this is a newbie questions (I feel stupid asking it) where is the sensor located?

smtippin

Right above your oil filter. It is the thing you think you're going to break and wish wasn't there when you stick you hand on the filter to pull it.

s

smtippin

I figured it was the sensor, just didn't know all the tech on it. I mean, when you're idling at the stop light and the pressure gauge bounces all over the place, you know something must be screwy.

s

5-90

Yah - as long as your idle speed is steady, your oil pressure should be steady. It's possible that the pressure relief in the oil pump is failing (spring going soft on you - it's happened,) but it's relatively rare. Much more likely that you're losing the sensor - and the sensor is easier to replace anyhow.

Find the oil pressure sensor on the 242ci just above the oil filter and just aft of the distributor (or camshaft SYNC sensor, if you are distributorless. The cam SYNC dingus also drives the oil pump from the camshaft.) There's a special socket that fits the scallop on the black/silver one, or the yellowish bell-shaped one will take a regular open-end wrench (7/16", 1/2" or 9/16" - I don't remember.) If you're in a hurry, you can unloose the old one using a big pair of slip-joint pliers. Then, install the new one (using RTV copper if you want to use something on those tapered pipe threads) and turn it until it's "finger-tight." Give an extra 1/6-turn using the plilers, and you'll be ducky. (Clean the area and verify no leaks after 2-3 days' service. Tighten PRN.)

Bigclubs

Yep, my 96 did the same thing, was driving when the oil pressure pegged to 80psi and later dropped to normal. Stopped at the local jeep dealer to ask about the pressure showing 80 and my mechanic friend said. "Change the sendor, they usually just go bad or a small speck of dirt gets clogged in the hole of the threaded orifice. Like he said pick up one at the local auto parts for @15.00 and change it youself. Just make sure they give you one for a Cherokee and not a Grand Cherokee. They are not interchangable. I had to return mine since it Was for a Grand Cherokee. Changed sensor and pressure has been good for 2 years now.

smtippin

Thanks. I did the gauge swap so I'm comfortable getting the right part and doing the install. I'm glad to hear it is likely just a sensor. It came off of an older model with ?? thousand miles so I wasn't planning on it lasting forever. I was just thinking the unit would simply peg out and stay there when the unit failed...not this poltergeist action.

Thanks,
s

00XJ

yep its deff the oil pressure sending unit. luckily on the 2000 its smaller than older ones so its not as in the way of the oil filter.

mike albo

also check the end that plugs on to the sending unit,the same thing happened to me,after changeing to sending units it ended up being the end,was really crispy and the wire was broken inside the plug.

95XJman

My 95 was doing the same thing. Replaced the sensor, fixed immediately.

mrmikey32

you dont need an oil pressure sensor.

if you stop smelling oil, you know you are out

Dan4governor

haha

tj40

ya, for sure on the oil issues. I feel like I'm fixing oil leaks every other season.