The Situation:
I installed a full gauge cluster a few months ago and performed the usual battery cable grounding to null the computer. Yesterday I swapped out to the water temp sender needed to run the gauge and currently have these indicated readings:

Oil Pressure: 60-70psi (not in the red area)
Water Temp: 215+ (drops to 210-212 at idle)

Notes:
Coolant was flushed and new 50/50 added at purchase (2-3 months ago).
Engine starts easily and runs smooth with SuperTech 10W-30 synthetic oil.
Fuel mileage is consistently 18+ mpg.

Questions:
Are these readings 'normal enough' not to worry over?
After a short test run, the electric fan was running at idle even though AC was never turned on and it was only 60-something degrees outside - is that normal?
Will the engine run better with a cooler thermostat?
If oil pressure is too high how do I bring it down?
Should I null the computer again and see if it readjusts itself?
Any other thoughts?

Thanks in advance for any insight you guys have on this...

 

Sounds a little toasty on the temp. When a/c compressor is off, ECU turns efan on at 218F coolant temp. Possibly the fan clutch is bad and/or radiator plugged.

 

210 degrees is the "normal" operating temp, and the oil pressure will change with RPM. 13psi is the lowest oil pressure at idle you want to see, and as a rule of thumb you would like to have at least 10psi for every 1000 RPM.

 

The thermostat might be beginning to 'stick' and not open up completely - I'll put in a new one - should I use a 195-degree stat?

The oil pressure is just below the red warning area - with 40 marked at the halfway point, the next mark indicates 60 - so I'm getting about 70 psi indicated. Would a battery terminals/computer reset 'recalibrate' that signal?

 

Wouldnt hurt to try, I mean its a free "test"

 

Your '96 is on the bubble like mine where it could have different parts...
Where is your coolant temperature sensor (the one that kicks the fan on) is it plugged into the back of the head, or down on the side of the block?
where is your coolant temperature gauge sender (the one that gives the gauge it's reading) on a bung off the front of the t-stat housing?
I've read of a lot of different numbers, but most don't usually report where their temp probe is on the motor.
Pretty sure OEM thermostat is 195, but a lot of guys run 180.
How long at idle is it taking the electric fan to come on? Stationary, idling, is where my cherokees starts to heat soak, but it takes a good bit to get there.

 

When it comes to oil pressure, it's always a good idea to let a shop verify pressure with a known accurate mechanical test gauge.

The coolant temp sensor (ECU/efan) is in the t-stat cover on the front of the motor. I believe '96 down XJs also have a sending unit in the back of the head, driver's side but it's for the dash gauge only.

The t-stat could be the issue but don't be surprised if changing it, the results stay the same. When it comes to the XJ cooling system, ALL components must be in top notch condition. Replacing parts one at a time means draining/re-filling coolant more than once also.

 

I run about 215 and Ive done the entire cooling system, and a head gasket. runs fine for me

 

Does u're efan run when a/c is off and what ambient temps? The OP stated his efan was running when a/c was off and in 60F ambient......that to me seems like the motor is a little toasty for those operating conditions. Ones got to remember, XJs with standard cooling (no a/c) did not have an efan but apparently ran cool enough with a single belt fan, presuming all other cooling system components were functioning correctly.

 

Mine runs just a tiny bit over 210, I just ordered a fan shroud since I dont have one and am gonna see if that brings the temp down.
If you dont have a shroud, I recommend getting one, otherwise the fan doesnt really do its job too well.

 

Actually (and I'm being facetious here), the fan does it's job (move air) with or without a shroud. The key to it is, any air that does not move thru the rad is wasted air movement. The shroud insures that most of the air moved by the fan is moved thru the rad.

 

i run below 210 without the shroud. but i do recommend getting one, i've already got my finger in there once

 

mine usually runs between 200 and 210. in the time i have owned it, it has never gone over 210.

 

Man I tell ya since I flushed the system and replaced the thermostat (195*) its been running at 195... sorta scaring me. Oil pressure 55 cold start idle 20 hot idle. 5-30 full synthetic wix filter.1990 4.0 133000 miles. Fan should kick on in the 215 range.

 

E-fan wouldn't engage for AC or over heating, tried replacing relay/ sensor to no help so I stopped wasting money and hooked it up to a toggle switch. Eventually deleted entire AC system anyway.