Nightsky

I've looked around and only found this as a similar issue. A cut wire does not seem to be my problem. https://www.cherokeeforum.com/f2/oil...moving-163386/

Have an 88 Jeep Wagoneer Limited (XJ) that shows low oil pressure. The lower end was rebuilt by a shop for the previous owner so I have little details about what was done there. The oil pressure was showing 0 when off, 20 when running, and would not move with higher RPM's. Recently the oil pressure gauge stopped moving to 20 and only moves to 10. I disconnected the oil pressure sending unit and it pegged to 80. I have also ran Weedeater string down the sensor hole to try to clear any blockages and changed the filter with no change. I plan to flow oil out the sensor hole to confirm it is clear and change out the sensor to start with.

I've searched the net and not found an issue like mine with a gauge that moves to one pressure and then stays that way... Any tips?

Mike

md21722

I would treat this as an electrical/sensor problem, not a mechanical one. The engine simply doesn't work at 10 or 20 psi continuously when on. Sometimes the sensors fail and it will peg, sometimes they fail and read low(er), .... they can and will fail.

Firestorm500

For sure verify with a mechanical gauge before going any farther.

What if your gauge is right?

Nightsky

Yeah, forgot to mention that this is not a daily driver, so it has been parked since this occurred.

I bought a BWD S768 Oil Pressure Switch (Sender) from O'Reilley's for $20. It now reads around 60 at start up, drops to about 30 at operating temp and idle and runs around 40 at cruise.

My concern now is I punched it up to 55 and it pegged out past 80. I'm guessing now I need to re-calibrate the gauge, or can that be done? Of course this is a 25 year old vehicle so it could be corrosion of the connections adding some resistance. Does the gauge add or remove resistance as it goes from 0 to 80? I'm thinking it adds resistance since removing the sensor pegs it to my recollection. If that is the case I might be in for a good contact cleaning...

Mike

md21722

There's no recalibration of the gauge. When the entire instrument cluster or PCM is changed there is a sync procedure but that's it. My guess is that the O'Reilly's sensor isn't quite up to snuff. Dealer or NAPA Echlon work best. There are problem reports with everything else. I don't think you have any mechanical problems because the relief spring is set to 75 psi. Basically a pegged gauge means electrical/sensor problem.

Nightsky

I think I'm fine with it showing a bit high. Just some resistance issues affecting the overall voltage output I'm sure. At least I can tell I have pressure and it is moving. I'll drop a mechanical on it sometime soon to check how much it is off, but at least I feel safe driving it again.

Mike

RTorrez1

Take it back and get one from the dealer. When the gauge read 80+ psi the sending unit is garbage. Very common for aftermarket sending units. Plus do like Firestorm500 said and verify the pressure with a mechanical pressure gauge and that will tell you what the pressure really is.