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Oil pressure drops at idle and changing oil pump. 2001 xj 4.0 i6
#16
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Year: 2004
Model: Grand Cherokee
Engine: 2000 4.0
I traveled down that same path when I bought my first jeep,yup,filters,oil weights,pump,bearings head check and still 4-5 psi and check gage alarm. I am a very experienced mechanic but that was my first encounter with the 4.0 engine. After much research I found this to be a common problem for that year and a few years before. That was also the same years for the cracked 0331 head issues which will destroy bearings and cause low oil pressure. BUT jeep also had the pressure problem too....non related to the head.
There have been 4.0s rebuilt by professional engine builders that have come bake with low oil pressure. There has to be an explanation but I failed to find it.
#17
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Year: 1998
Model: Cherokee
Engine: 4.0
Not to burst your bubble but the likelihood of 2 bad filters in a row is slim to none.
I traveled down that same path when I bought my first jeep,yup,filters,oil weights,pump,bearings head check and still 4-5 psi and check gage alarm. I am a very experienced mechanic but that was my first encounter with the 4.0 engine. After much research I found this to be a common problem for that year and a few years before. That was also the same years for the cracked 0331 head issues which will destroy bearings and cause low oil pressure. BUT jeep also had the pressure problem too....non related to the head.
There have been 4.0s rebuilt by professional engine builders that have come bake with low oil pressure. There has to be an explanation but I failed to find it.
I traveled down that same path when I bought my first jeep,yup,filters,oil weights,pump,bearings head check and still 4-5 psi and check gage alarm. I am a very experienced mechanic but that was my first encounter with the 4.0 engine. After much research I found this to be a common problem for that year and a few years before. That was also the same years for the cracked 0331 head issues which will destroy bearings and cause low oil pressure. BUT jeep also had the pressure problem too....non related to the head.
There have been 4.0s rebuilt by professional engine builders that have come bake with low oil pressure. There has to be an explanation but I failed to find it.
The check gauge light coming on and oil pressure dropping that much can't be normal. I have a 1998 4.0 and I hold steady at 10-12 psi at idle, and anywhere from 30-50 while driving.
#18
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Year: 2004
Model: Grand Cherokee
Engine: 2000 4.0
It IS possible to have two bad filters in a row for this engine if it isn't the right kind. The 4.0 is finicky about its oil filter.
The check gauge light coming on and oil pressure dropping that much can't be normal. I have a 1998 4.0 and I hold steady at 10-12 psi at idle, and anywhere from 30-50 while driving.
The check gauge light coming on and oil pressure dropping that much can't be normal. I have a 1998 4.0 and I hold steady at 10-12 psi at idle, and anywhere from 30-50 while driving.
No I did not say low oil pressure for these years was normal....I said it was a COMMON problem.
What has the greatest effect on pressure that people overlook? Worn lifter bores, bad block casting or mis alignment when oil gallies were drilled/crossdrilled. A leaking oil galley (or missing galley plug) is not an unheard problem.
#19
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Year: 1998 Sport
Model: Cherokee
Engine: 4.0
Not to burst your bubble but the likelihood of 2 bad filters in a row is slim to none.
I traveled down that same path when I bought my first jeep,yup,filters,oil weights,pump,bearings head check and still 4-5 psi and check gage alarm. I am a very experienced mechanic but that was my first encounter with the 4.0 engine. After much research I found this to be a common problem for that year and a few years before. That was also the same years for the cracked 0331 head issues which will destroy bearings and cause low oil pressure. BUT jeep also had the pressure problem too....non related to the head.
There have been 4.0s rebuilt by professional engine builders that have come bake with low oil pressure. There has to be an explanation but I failed to find it.
I traveled down that same path when I bought my first jeep,yup,filters,oil weights,pump,bearings head check and still 4-5 psi and check gage alarm. I am a very experienced mechanic but that was my first encounter with the 4.0 engine. After much research I found this to be a common problem for that year and a few years before. That was also the same years for the cracked 0331 head issues which will destroy bearings and cause low oil pressure. BUT jeep also had the pressure problem too....non related to the head.
There have been 4.0s rebuilt by professional engine builders that have come bake with low oil pressure. There has to be an explanation but I failed to find it.
#21
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Year: 1994 Limited Edition
Model: Grand Cherokee
Engine: 5.2 L V8
I also tried this:
http://www.jeepforum.com/forum/f19/4...fixed-1304679/
If you dont click on the link here is what I did... I took off the oil pressure switch for the electric guage again. I took pipe cleaners and tried to clear the passage to the gauge in case there was a bottleneck of sludge or something in there. Then I put in a brass hose fitting into the threads where the switch goes and ran a hose to a drain pan from there. I started the engine and increased rpms to about 4000 for a few seconds. About a quart or little more of oil came out. I added more oil, and tried it again. Added more oil, and hooked the switch back up and took it for a drive. Same issue.
#24
Put 20w50 in it and if the oil pressure comes up replace the bearings. You can get to all or most of the bearings underneath and replace the rear main at the same time. If its not making any noise then the crank and rods are good.
#25
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Year: 1994 Limited Edition
Model: Grand Cherokee
Engine: 5.2 L V8
But I didnt buy a 4k truck to immediately pull it all apart and have to do motor work (something I dont know how to do). I took the truck back to the guy I bought it from this evening. He has better mechanical knowledge and proper equipment to do that sort of work. We have an agreement written up and I should know more by thursday. Hopefully I'll either end up with a properly running truck or my money back.
I'll report more as this progresses. More thoughts and ideas are very welcomed still.
#26
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Year: 1998
Model: Cherokee
Engine: 4.0
have you researched the 0331 head issue? read up on it while the truck is in the shop, did you notice if the coolant level had dropped at all while you had it? click the link to do some research on the head:
https://www.google.com/search?q=cher...hrome&ie=UTF-8
https://www.google.com/search?q=cher...hrome&ie=UTF-8
#27
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Year: 1997
Model: Cherokee
Engine: 4.0 straight 6
im really happy someone else brought this up....i recently bought a 97 xj and at start up and while cold i run a solid 45 to 48 pounds of pressure....but once it gets to operating temp, 2k and above i still have 45 to 48 psi...when its at idle i drop to 15 to 18 psi......really happy to hear this is normal.
#28
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Year: 2000
Model: Cherokee
Engine: 4.0L I6
im really happy someone else brought this up....i recently bought a 97 xj and at start up and while cold i run a solid 45 to 48 pounds of pressure....but once it gets to operating temp, 2k and above i still have 45 to 48 psi...when its at idle i drop to 15 to 18 psi......really happy to hear this is normal.
#29
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Year: 1998
Model: Cherokee
Engine: 4.0
im really happy someone else brought this up....i recently bought a 97 xj and at start up and while cold i run a solid 45 to 48 pounds of pressure....but once it gets to operating temp, 2k and above i still have 45 to 48 psi...when its at idle i drop to 15 to 18 psi......really happy to hear this is normal.
to the OP, sorry to hear the filter wasn't the issue. However, now you can have peace of mind that you have the best filter you can get. Your 4.0 will be happy about that...but I'll agree with the others, monitor the coolant level or anything unusual with the cooling system.
Originally Posted by Turbo X_J