• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

2001 XJ ZERO OIL PRESSURE AT WARM IDLE

L

lokiraccoon

NAXJA Forum User
Location
Ohio
Cold start pressure is around 40.. as engine warms it slowly drops to ZERO! light comes on. Engine isn't making any noises, sounds great and runs great. Changed the sending unit, no change. Did oil change, no change. Checked with mechanical gauge and confirmed that it in fact is losing oil pressure. Has 134,000 miles. Oil pump? or worn out engine? :wow:
 
Hmmm, a 2001 with low oil pressure. Have you checked for the infamous cracked head issue associated with the newer style cylinder head? Even small amounts of coolant in the engine oil over time will damage the engine bearings. Usually it starts with the cam bearings first and then works its way to the rods and crank bearings.

It may be worth the time to drop the oil pan check to see if the oil pick-up tube screen is restricted. You can also check the rods and main bearings for wear/scoring with the pan off.
 
Is something that just happened? If it reading 0 after warm up on a mechanical gauge,
it sure seems like it would make a racket.

I'll guess oil pump. Please let us know!
 
Im very new to this and cant seem to find any threads about it..?? ill keep trying to learn lol.. It isn't losing any oil so cant imagine cracked head. I just bought it 2 wks ago and this is how I got it. I just assumed it was going to be sending unit and ofcourse just my luck it wasn't. Going to try oil pump tonight as long as I can find one
 
Could be a failing oil pump or clogged oil pump pickup screen. Might be a good opportunity to replace and ugrade along with replacing your rear main seal and re-torquing your main bearings as they have a tendancy to loosen over time. I believe spec for the 4.0 warmed up is 13psi.
 
lokiraccoon said:
. It isn't losing any oil so cant imagine cracked head. I just bought it 2 wks ago and this is how I got it. I just assumed it was going to be sending unit and of course just my luck it wasn't. Going to try oil pump tonight as long as I can find one
Click to expand...

Is the oil clean, not showing signs of milkiness? Look inside the oil filler cap and valve cover, is it clean or is there a brown foam. Is it using coolant?
If no to these answers, it probably isn't a cracked head.

If there was absolutely zero pressure at idle, the lifters would collapse and chatter badly.
If you go ahead and change the pump, take the time to pull the main bearing caps, one by one, and check the condition of the journals and insets for wear. Do the same with the rod bearings. Make sure to torque the caps back to specs. Badly worn bearings should be obvious.
Here is a site with dozens of bearing inserts photos, showing various types of wear and their causes. Bookmark it, it is a great resource.
http://catalog.mahleclevite.com/bearing/
Clean the oil strainer. If the pan is load with crude, it could be partially plugged.
 
lazyxj said:
Is the oil clean, not showing signs of milkiness? Look inside the oil filler cap and valve cover, is it clean or is there a brown foam. Is it using coolant?
If no to these answers, it probably isn't a cracked head.

If there was absolutely zero pressure at idle, the lifters would collapse and chatter badly.
If you go ahead and change the pump, take the time to pull the main bearing caps, one by one, and check the condition of the journals and insets for wear. Do the same with the rod bearings. Make sure to torque the caps back to specs. Badly worn bearings should be obvious.
Here is a site with dozens of bearing inserts photos, showing various types of wear and their causes. Bookmark it, it is a great resource.
http://catalog.mahleclevite.com/bearing/
Clean the oil strainer. If the pan is load with crude, it could be partially plugged.
Click to expand...

The oil is clean! its not going through oil or coolant, that's all great.
Pulled the oil pan last night, found a few decent little chunks of metal. also a crack where the oil pump bolts on, the one whole flange is completely cracked being held up still with gasket. Took one cap off rod and inspected bearing, has a little scoring, other than that its just really worn down. going to check the rest of the bearings tonight and hopefully get to checking the mains. Just deciding if I should just do the main and rod bearings and oil pump or take it and have it overhauled..?
 
with small chunks at bottom of oil pan do you think its something to worry more about or just get the bearings and pump done and put her back together?
 
First, welcome to NAXJA:)

What's the history of the Jeep? Any idea what kind of maintenance she received? At 134,000 miles, a 4.0 is just getting broken in! I would think bearings and pump would do it.

Have you checked the compression and read the plugs?

This is the forum to belong to owning an XJ. Hopefully one of the real experts will give you their opinion.
 
I am not sure on history, just got it and guy didn't tell me much. He said when he got it it was just stock and had never been off road then he put the lift on it and he only put like 3,000 miles on it but he didn't take it off roading. condition of everything underneath is mint so I couldn't imagine he beat it up to much. It has a death wobble from 45-50mph and the low oil pressure, other than that its amazing. I have not checked the compression, deffinatly will be once its back together. What do you mean read the plugs?
 
Just google "spark plug reading" and it will show pictures of spark plugs showing different engine conditions: rich, oil soaked, lean, etc. Usually "normal" is a light tan, and if they all
read, ie look, the same, that is a good thing:)
 
You must log in or register to reply here.

Similar threads

J
Running just fine then dies at idle on street
Replies
4
Views
2K
90xj06
9
M
Oil pressure question
2
Replies
26
Views
3K
Money_Pit_Incoming
M
A
00 XJ - Low oil pressure at hot idle. Compression and analysis are good, what's next?
Replies
12
Views
2K
sixditchoffroad
sixditchoffroad
M
1992 XJ A/C Air Conditioning Replacement - Parts List
Replies
7
Views
2K
Rob Mayercik
R
C
Oil Pressure Sender Woes
Replies
3
Views
907
RCP Phx
R
Back
Top