High Oil Pressure Reading - Sending Unit?

Quick question for y'all.

'99 TJ Sahara, 128K miles, no major engine repairs yet except for the exhaust manifold. Last oil change was about a month ago, with synthetic

5W30.

We got hit with the cold today, and on the drive home from my mother-in-law's, I saw that the oil pressure gauge was at 80. It normally runs the 20-60 range. The engine seemed to warm up quicker than it usually did (but then it had been driven for 2 hours on the way up, and only sat for about 3.5 hours before we headed home). When I took off the gas, the pressure gauge came down to 60. As we continued driving, it slowly crept down, so by the time we got home half an hour later, it was at 60 at 2000 RPM, and 40 at idle. The engine temp stayed at 210.

Some quick research showed that this is probably the oil sending unit, but the fact that the pressure gauge dropped over the course of the drive home has me wondering - if it were a bad sending unit, wouldn't it have stayed at

80?

Thanks for any thoughts or recommendations.

Tirya

-- TDC Inca Jeeper A girl and her Jeep... it's a beautiful thing...

Reply to
Tirya
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Tirya did pass the time by typing:

Not always. Might pull the electrical connector off the sending unit (down by the oil filter), clean it, and put it back.

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A little crud knocked loose by your switch to synthetic may also be the cause. (If you neglected oil changes prior to this. IF you did regular changes 3,000

-4,000 miles then this probably isn't the case)

Reply to
DougW

I would be suspicious of a failed filter. If the filter fails internally, the oil pressure spikes and the bypass valve shunts it past the filter.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Tirya wrote:

Reply to
Mike Romain

Reply to
twaldron

That happened to me one time in my Ram and my bud said check the filter because the sending unit checked out. I pulled the filter and cut it apart and found that the paper, yes paper filter material had collapsed. I will never use FRAM filters again, not even their high end ones. I guess any filter can fail.

HarryS

Reply to
HarryS

I wouldn't worry if this is a single event kind of problem. It sounds like the pressure went up because the oil was thick due to the cold. If the pressure remains high when the weather warms, then start to look for causes.

You did not say what the temps were outside, but if they were so low as to drive the oil pressure up, then I woulud suggest switching to 5w30 or 0w30 for winter, then back to 10w30 or 10w40 for summer.

Reply to
Jeff Strickland

Reply to
L.W.(ßill) Hughes III

When our '95 Cherokee sender failed it pegged the needle reading high.

Reply to
Rich M

Her's varied, it didn't stay pegged....

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Rich M wrote:

Reply to
Mike Romain

they default to high upon failing. Mine did also... scared the bejesus out of me... especially since I was on the trail... Nick

Reply to
Nick

If this vehicle is set up the same as my 00Cherokee you can check the dash panel by turning the key to start (do not start the vehicle), and hold in the trip reset button.(about 5 seconds) It will go into diagnostic mode.Gages will read 20/40/60/80 and then return to 0. If the gage is fine disconnect the sender and check for 5Volts at the connector. The ground should be fine as it is shared with other sensors which are working fine.The problem could be the sensor($30?)or in the PCM which sends the signal to the gage.

Reply to
DANFXR

Thanks for all the feedback, everyone!

A little more info - on Wednesday when it happened, we had temps in the low 30s - cold enough for a couple of inches of snow to stick, and some wind. (This is Dallas area, Texas). I forgot to mention that I checked the oil when this started on Wednesday night, and it was full, clear, and normal thickness.

We went out of town for the holidays and I just picked the Jeep back up. It's in the 40s right now, and the oil pressure is still reading high, but is not maxed out.

So I figure I'll grab an oil filter on the way home and give that a shot. Means I get to use some of the new tools I got for Christmas! ::grin::

Tirya

-- TDC > Her's varied, it didn't stay pegged....

Reply to
Tirya

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