After driving my "new" '87 XJ for a few days I have noticed that the oil pressure gauge will read around 40psi when cold, and then drop down to around 20 psi at idle and 25-30 psi at hwy speed when warm. I have also noticed an intermitent ticking noise, sounds like a stuck lifter. It only does it some of the time at idle, don't hear it when driving down the road.

It just turned over 227,000 miles today. Would this be considered acceptable for a wornout, 25 yr old engine? I know it's not ideal, but it seems to run ok, and the oil gauge never drops below 20 psi.

 

Mine does practically the same thing


13 psi is absolute lowest you can run, id say your fine but might wanna look at a new oil pump/pickup relatively soon

 

It's fine. Drive it.

 

it's normal
but if you want to be sure, have it checked with a mechanical gauge

stock gauges are more like an approximation based on a guess

 

Awesome, thanks!

 

What brand of oil filter is on the Jeep now?

 

mines hits the peg when it gets power... like engine not even running. they aren't too accurate lol.

 

The spec for oil pressure is not less than 13 psi at HOT idle and between 37-75 psi over 1600 rpms.

I agree that verifying with a "mechanical" gauge would be a good idea. Many parts stores will rent you this tool inexpensively. There can be some inaccuracy between the oil pressure sending unit and the gauge.

And if your pressure is below spec, I wouldn't be overly concerned. I've seen many engines go tens of thousands of miles with below spec oil pressure.

 

Ok,

Today I noticed the oil pressure gauge now reads between 10 and 20psi at hot idle. It used to be at 20 psi. Is the guage faulty or a bad sending unit, or is my oil pump going out? It still reads about 22psi at highway speeds.
I am planning on checking it with a mechanical gauge this next weekend.

Also, the temp gauge only goes up to 180-190 at highway speeds. It doesn't show any signs of overheating, but it makes me nervous that it never goes any higher than that (it was 102 degrees outside today).

My question is: is it ok to keep driving it the way it is? I only drive it in the morning and evening when it's not quite as hot outside.

 

You haven't answered the question I asked a few posts ago. What brand of oil filter is on the Jeep now? 22 PSI while driving is quite low. It's your engine.......

 

I don't know what kind of filter it is. It's white, that's all I know. I was planning on changing the oil soon anyway, should I just change the oil pump at the same time?
I know on some vehicles (like my '77 Dodge) you have to pull the engine up a bit to remove the oil pan. Do you have to do that on a 4.0 4x4 XJ?

Also, is the coolent temp sensor/sending unit easy to replace? If it is, I will do that at the same time too.

 

Find out the brand of oil filter first. That could be your problem. A cheapie oil filter.

 

Seriously? I didn't know a cheap filter would cause a 20 psi difference (my 20psi vs. typical 40-50psi at hwy speeds). I would still have to change the oil to change the filter wouldn't I? I know the filter is above the oil pan.

 

Absolutely could be your problem. And no you don't have to change the oil, just the filter.

 

second thought is what oil is in it. if you have a lose engine and are running 5-30 you will have less pressure than 10-40. with your mileage i don't see any reason not to run a 40w oil