Hi all. First time posting. I know there has been a million posts about this issue, trust me I've been all over them for the past couple of weeks, but all of them seem to end with "sending unit." If anyone can help I would greatly appreciate it. Here is the rundown of my situation:

4.0 I6
150,XXX miles
10w-30

Cold start: 40 - 45 psi
Hot idle: 8 - 9 psi
1600 rmp (cruising): 20 psi
Head gasket repaced within the last 1k miles and there does not appear to be any cracks in the head or coolant in the oil.

Shortly after buying the XJ I found that my oil pressure gauge would randomly drop causing the check gauges light to come on, especially while off-road. I checked out the sending unit and saw that there were loose connections on the connector, so I replaced that with a new one from NAPA. When I saw that the pressure was still running low I had a mechanical test done and confirmed that the numbers that I am getting are accurate. After the test I had an oil change done, replaced the oil filter (NOT a fram) and added a bottle of slick 50 but saw no change.
So now that I have ruled out the sending unit, how much trouble am I in? I suspect the issue is warn bearing, but I am not getting any unusual knocking sounds from the engine. At 20 psi how far can I safely drive without doing catastrophic damage?

Again, any assistance would be greatly appreciated.

 

The damage is already done, hence the low oil pressure. Some guys report running for a long time with lower oil pressure...buuut you know the deal on that one.

 

http://www.jeepforum.com/forum/f19/4...fixed-1304679/

Maybe you'll get the same result.

 

oil pressure was fine before head gasket?

 

Not sure. I asked the PO and he said that it idled around 13psi hot.

 

I failed to mention that I tried that prior to the oil change. I pulled the sending unit and hooked up a hose and jug, revved the engine for a few seconds to blow out any chunks. Oil came out blackish, that's about it. I couldn't get the elbow off, but I ran some pipe cleaners down it today and didn't produce any substantial crud.

 

Additionally, when the engine is running I can visibly see oil flowing over the head when looking in the oil fill location.

 

head gasket was replaced before you bought?

you knew this?

 

My oil pressure went negative, shut it off, waited a few minutes & it went back to normal. As soon as I found a parts store I swapped out the Fram oil filter for a different filter & it never happened again.
Not saying that is your problem, just throwing it out there.

 

Yes. Apparently it was replaced due to a minor leak along with the oil pan gasket, rear main seal, trans pan gasket, and a host of other things.
Poor judgement on my part?

 

High mileage, low oil pressure is nothing unusual. If wear is equally the same throughout engine the accumulative effect will cause low pressure....BUT, and this is interesting: the clearances can still be within the high end of factory specs!!

• No knocking is a good sign
• The fact you have some pressure means you have oil flowing through engine
• Pressure is not a function of reliability...it is an indicator of wear
• How far and how long your engine will last is a crap shoot
• Don't use slick 50 or heavy oil....it will raise pressure only because it reduces the flow! Flow is what lubricates....do not restrict it with thick sh**.

FYI I have driven almost 70k miles with lower pressures than you posted

 

Thanks, bigbadon. That's relieving to read. I spoke to a mechanic that frequently works on Jeeps and he suggested that I not even drive it the 45 minutes or so to their shop and that I should have it towed instead. Seems like he was exaggerating a bit.