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oil light comes on and off as i stop

A

AJTorris

NAXJA Forum User
Location
California
Ok 1992 xj. I just put in a new motor about 5K miles ago. Ive done 3 oil changes. I replaced my old motor with a long block, new oil pump, water pump, power steering pump, radiator, new radiator hoses, new trans lines, new fuel pump, new fan....

So heres my issue:

After driving a bit my oil light will come on when i stop. Go back out as i give it gas or drive. Figured it may be low on oil. Turns out it wasnt. Did an oil change and still having the issue. Im running 10w-30. Thinking ill try a little thicker oil. But what causes this? It only started happening since it has warmed up here in bakersfield. typically on days about 95 degrees.

!!!1
 
I had this exact same issue with a Volvo I had. No idea if this fix will work for you, but I found that when I came to a stop in drive, the idle would drop down to where the oil pressure was low enough to trigger the oil light. It didn't do it in park or when driving. Mine had an issue with the vehicle speed sensor from the speedo was broken and the computer had no idea how fast the car was moving or if it was or was not stationary.

Check your idle speed, you might just be idling too low.
 
OK i might have to do that. I know i had to mess with it a long time ago with the old motor... that could be it. I dont think so but i will definently check that out. thanks
 
your light is triggered by oil pressure-- look for things that would decrease pressure in the engine:

1.) oil starvation at the pump (low fluid level, misaligned oil pick up screen, or a leak between the screen and the pump)

2.) loss of pressure after the pump pushes the oil toward the engine (worn bearings creating loose clearances or a leak between the pump and the block)

3.) faulty oil pump unable to create sufficient pressure

4.) low pump speed due to low idle speed
 
Jnida63 said:
could be a faulty sending unit also
Click to expand...

This ^ If you have/have access to a mech oil pressure gauge, install it and drive it. See if your oil pressure is good. If so, check wiring and replace oil sender.
 
NORMAL OIL PRESSURE
Normal oil pressure should be 37-75 psi (2.6-5.3 kg/cm  )
maximum above 1600 RPM. Minimum oil pressure should be 13 psi (.9
kg/cm ) at 600 RPM.
 
Here is a possible fix for an XJ in Bakersfield... Drain the oil. Install a new Wix51515R oil filter. Fill it up with 20w50 Castrol Racing oil, and drive. Never, evah run a Fram oil filter on a Jeep. They just kill the oil pressure, and Wix 51515R is the best !
 
my oil gauge would actually fluctuate when taking turns and straightening out i replaced the oil pressure sensor which fixed it a little bit. Then i switched over to a mechanical gauge which gave a more precise reading but involved having to look down to see the pressure while driving. I eventually just switched back to the gauge in my cluster. my guess the Autozone "Duralast" sending unit isnt that great.
 
Last edited:
Have your checked the wiring to the gauge? Also check the ground strap to the firewall, remove bolt, sand, replace.

Sort of off topic. It's not difficult to swap out the instrument panel gauge cluster to a full set. Then you'll have water temp, oil pressure and tach., you can keep your original speedo without too much extra trouble.

Mike
 
grounds have all been cleaned connected and then coated. those are all good. After driving it over the weekend i noticed it went down to about 15-20 psi at idle. I am running a fram oil filter. I will buy a different one and see if it makes a difference. At driving it reads right about 35-60 depending on the rpms im pushing.
 
FRAM is very bad on a 4.0 Jeep. The Wix 51515 works well, and the Wix 51515R is even better !!! If you want to fix the light issue on the cheap, get the WiX-51515 filter and a bottle of STP oil additive. On the high $$$ path, get the Wix 51515R filter, 6 quarts of 20w50 racing oil, and it will run like a new XJ !!! Down the road, get a new MOPAR High Volume oil pump and a full set of connecting rod bearings that are + .001 from what you have now. Best of luck !
 
Buy a mechanical gauge, or rent one. Harbor Freight has one for $25. I just
checked my oil pressure because it was showing 80 psi at start up, which was higher than it ever has been. I had some start up "dry start" noise, and so replaced my Pure 1 filter with a Bosch D+. The noise has not been back,
but the oil pressure stayed the same 80 psi at start up. After warm up it shows 28 psi with Rotella T 15-40 at idle.

Anyway, I hooked up the mechanical gauge and it showed about 70 psi. What was interesting to me was as I increased the RPM's it would go to about 75 psi, and drop back to below 70. I am thinking this is the oil pressure relief valve on the pump opening. Correct Cruiser54? Kind of like a rev limiter.

The mechanical gauge will give you the data to proceed from there.
 
AJTorris said:
grounds have all been cleaned connected and then coated. those are all good. After driving it over the weekend i noticed it went down to about 15-20 psi at idle. I am running a fram oil filter. I will buy a different one and see if it makes a difference. At driving it reads right about 35-60 depending on the rpms im pushing.
Click to expand...

Here's what I predict.

When you remove the Fram, little to no oil will come pouring out of the filter because it has such a poor anti-drainback valve.

Your oil pressure will increase with the installation of a Wix.
 
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