Question regarding oil pressure and if I should be worried. So I just bought this 95 XJ. It has 201k miles on it. The previous owner said he just put fresh oil and oil filter on it. On the way home from work today, at idle the pressure seemed a bit low to me. Somewhere in the 10 psi range. Then at a stop light, it dropped to around 5. Then again at another light, it wasn’t much above 0. Then it would fluctuate at lights between 0 and 5. Do you think this is a sending unit issue? Should I swap that out? Put a mechanical gauge on it? The truck seems to run fine and has no issues that I can tell.

 

Welcome to CF
First you could pull the sending unit and see if it and the orifice where it screws in are clogged. Before replacing it have someone bump the starter after disconnecting the coil wire to flush out the orifice. Also clean the electrical connections. If this doesn't help I'd verify the pressure with a mechanical gauge.

 

thank you. I’ll start checking it all this weekend. Hopefully something simple.

 

What brand of oil filter is on it?

Is the oil sending unit leaking into the connector?

Take a peek into the oil filler hole and see if it might be sludgy.

 

FWIW the old drag racing rule of thumb for oil pressure is you need 10 pounds of pressure for every thousand rpm.

 

Did it do that when you test drove it? Still have oil on the dipstick?

I wouldn't drive it until you verify whether you have good oil pressure with a mechanical gauge. Spec for this engine is 13-psi at idle (600 rpm) and 37-75 above 1600 rpm.

 

Ok just a Question , What oil are you using ?

 

And with those words, tech started the later infamous 2021 oil war...😂😉

 

Post 4.......

 

Ya I know sorry but we do need to know . is he using a 10w-30 or 10w-40 , or maybe a 5w-30

 

YES!! We need to know all of the answers, but we ain't getting any.

 

Use a Motorcraft FL1A filter and 15w40 diesel oil.

 

Oh dear...

 

Regardless on which oil, you need to figure out if the gauge is reading correctly. If you really have oil pressure that low at idle, switching to thicker oil and saying a small prayer for your bearings is not the solution.

 

Sorry guys. Took me a couple of days before I got to it. Think I found the problem. Oil is 10W30 and a wix filter. Started diagnosing today and found the wire was exposed. Going to cut that section out and splice back together tomorrow morning. Going to try and clean it up as well. Everything is caked an oil. Going to have to find the oil leak next.