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Low Oil Pressure at idle

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Old Jan 12, 2018 | 10:13 AM
  #16  
robsjeep's Avatar
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From: San Mateo, CA
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0 Renix, stock.
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Originally Posted by cruiser54
Fram is known for having poor anti-drainback valves. This is critical on our Jeeps because the oil filters mount sideway or worse yet, upsid down. This causes your Jeep to start with little or no oil in the filter feeding the bearings air instead of oil. Done repeatedly, bearing damage does occur.
There have also been reports on the different Jeep forums of low oil pressure and the owner's removed the Fram filter, cut it open, and found the internal filtering material unglued and disintegrating.

Check out this link for more info.

http://minimopar.knizefamily.net/oil.../opinions.html
fram is JUNK

On another car, vw vanagon installed a fram oil filter, had horrible lifter noise at start up only going away after a mile of driving, did this several times, if the van sat off for more than an hour, I got the start up noise. Removed the Fram and installed a VW filter, and the noise never happened again. ( filter is mounted at an angle on the van, drain back issue)

On yet another car, I removed the fram (this one mounted vertically, threads on top, so no drain back issue) and found the guts had come loose, rattling around inside the filter can, no filtering occured, and dirt trapped was able to be washed into the oil flow. the filter element was supported by failed cardboard! I have since cut open many brands of filters, some are cheaply made, cardboard supports that warp and fail, verse metal that stays in place, cheap rubber check valves that have hardened or cracked, verse soft pliable silicone valves that seal. little filter media material with few pleats, verses large double the area filter media. Small filter media area, specially with fine filter pores means greater pressure drop, thus more likely filer goes into bypass. Even the much admired fram HP1 filter is crappy internally, I run a Motorcraft racing filter in that application (Full flow modified Porsche 914). K and N also makes a very well built filter, thats what I run on my Van now and the higher end WIX is pretty well made for my Triumph and Buick powered other 914.

also beware of cross referenced filteres, the tables found in the books at many autoparts stores list what fits, but, if it fits it may not be correct, some have back flow valves, needed if the filter is orientated other than vertical, threads on top. others have no backflow valve, fine for vertical application, but not for other orientations. there is also the bypass valve, some motors have a built in bypass valve, some dont, if you instal a filter with no bypass valve on an engine with no internal bypass valve, you can blow the filter can open! there are different ratings for bypass valve opening and closing pressures. some valves are well made spring driven valves, others are wankly rubber thingys. so just because a cross reference table says it fits, that dont mean it is correct in regards to the valve opening and closing pressures (if the valve is even present) Some have the bypass valve at the bottom of the filter, so when it goes into bypass the dirt accumulated at the bottom of the can gets sucked into the oil flow, others mount the bypass valve at the top, much less likely to suck up dirt.
The data of valves, pressure rating, filter media area etc.. is almost never printed on the box, you need to research it on the web, the manufactures technical info can be found this way sometimes.

cut open your old filters, take a look, compair brands, huge differences in construction, some are scary.
also this website, Bobs the Oil Guy....

https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=cfrm

this site has lots of info on not only oil, but filters too.


FRAM is the Orange Can of Death!


keep jeeping!

Last edited by robsjeep; Jan 12, 2018 at 10:22 AM.
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Old Jan 12, 2018 | 08:03 PM
  #17  
cruiser54's Avatar
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
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Originally Posted by robsjeep
fram is JUNK

On another car, vw vanagon installed a fram oil filter, had horrible lifter noise at start up only going away after a mile of driving, did this several times, if the van sat off for more than an hour, I got the start up noise. Removed the Fram and installed a VW filter, and the noise never happened again. ( filter is mounted at an angle on the van, drain back issue)

On yet another car, I removed the fram (this one mounted vertically, threads on top, so no drain back issue) and found the guts had come loose, rattling around inside the filter can, no filtering occured, and dirt trapped was able to be washed into the oil flow. the filter element was supported by failed cardboard! I have since cut open many brands of filters, some are cheaply made, cardboard supports that warp and fail, verse metal that stays in place, cheap rubber check valves that have hardened or cracked, verse soft pliable silicone valves that seal. little filter media material with few pleats, verses large double the area filter media. Small filter media area, specially with fine filter pores means greater pressure drop, thus more likely filer goes into bypass. Even the much admired fram HP1 filter is crappy internally, I run a Motorcraft racing filter in that application (Full flow modified Porsche 914). K and N also makes a very well built filter, thats what I run on my Van now and the higher end WIX is pretty well made for my Triumph and Buick powered other 914.

also beware of cross referenced filteres, the tables found in the books at many autoparts stores list what fits, but, if it fits it may not be correct, some have back flow valves, needed if the filter is orientated other than vertical, threads on top. others have no backflow valve, fine for vertical application, but not for other orientations. there is also the bypass valve, some motors have a built in bypass valve, some dont, if you instal a filter with no bypass valve on an engine with no internal bypass valve, you can blow the filter can open! there are different ratings for bypass valve opening and closing pressures. some valves are well made spring driven valves, others are wankly rubber thingys. so just because a cross reference table says it fits, that dont mean it is correct in regards to the valve opening and closing pressures (if the valve is even present) Some have the bypass valve at the bottom of the filter, so when it goes into bypass the dirt accumulated at the bottom of the can gets sucked into the oil flow, others mount the bypass valve at the top, much less likely to suck up dirt.
The data of valves, pressure rating, filter media area etc.. is almost never printed on the box, you need to research it on the web, the manufactures technical info can be found this way sometimes.

cut open your old filters, take a look, compair brands, huge differences in construction, some are scary.
also this website, Bobs the Oil Guy....

https://www.bobistheoilguy.com/forum...s.php?ubb=cfrm

this site has lots of info on not only oil, but filters too.


FRAM is the Orange Can of Death!


keep jeeping!
You are correct. OCOD!!!!
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Old Jan 12, 2018 | 08:08 PM
  #18  
Caish's Avatar
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From: Arkansas
Year: 1987 & 1996
Model: Cherokee
Engine: 4.0
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ignore the gauge and use your ears.
if the lifters aren't tapping at idle you have enough oil pressure.
you should hear the old 258 in my wrangler before it burned the valves and quit.
It was slap worn out at idle warm, you would hear all the lifters go to tapping.
not uncommon for gauges to be wrong...
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Old Jul 13, 2020 | 07:37 PM
  #19  
Xjcherokee1998's Avatar
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Year: 1998
Model: Cherokee (XJ)
Engine: 4.0
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Originally Posted by Kowalski5599
My 98 XJ has 191,000 miles on it, and once the engine is up to operating temperature, my oil pressure drops to a few slivers above zero. Once I give it any gas it will go back to it's usual position between 1 third and halfway, I wonder if this is a sign that the oil pump is failing, there seems to be some oil very slowly creeping out from under the valve cover, so I wonder if that could have an affect as well... Thoughts?
I have the same issue. I replaced the sending unit with a pressure gauge for an accurate reading the sending unit is at least 10 psi off so my pressure is good.
Try removing the sending unit install a pressure gauge just for testing this will tell you if the sending unit needs to be replaced have a good one
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Old Jul 13, 2020 | 07:45 PM
  #20  
Xjcherokee1998's Avatar
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From: Canada
Year: 1998
Model: Cherokee (XJ)
Engine: 4.0
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Originally Posted by Kowalski5599
My 98 XJ has 191,000 miles on it, and once the engine is up to operating temperature, my oil pressure drops to a few slivers above zero. Once I give it any gas it will go back to it's usual position between 1 third and halfway, I wonder if this is a sign that the oil pump is failing, there seems to be some oil very slowly creeping out from under the valve cover, so I wonder if that could have an affect as well... Thoughts?
[QUOTE=Xjcherokee1998;3612985]I have the same issue. I replaced the sending unit with a pressure gauge for an accurate reading the sending unit is at least 10 psi off so my pressure is good. I'm running 10w30 with Lucas and the pressure is 30psi at almost 200 degrees with the pressure gauge at idle before with sending unit 10psi or lower.

Try removing the sending unit install a pressure gauge just for testing this will tell you if the sending unit needs to be replaced have a good
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Old Jul 14, 2020 | 03:11 AM
  #21  
dave1123's Avatar
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From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
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This thread is 2 years old, plus this topic has been discussed so many times it makes me sick to see another one. That's all I'm going to say about this.
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Old Mar 21, 2022 | 08:42 PM
  #22  
NE14ABJ's Avatar
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Default Oil pressure low at idle

I have had the head changed and piston rings and seals and now have low oil pressure has a mopar filter in it and 15w40 oil in takes longer to drop at idle but once warm drops to zero also had the oil pump changed
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Old Mar 21, 2022 | 09:16 PM
  #23  
cruiser54's Avatar
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From: Prescott, Az
Year: 1990
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Cam bearings are likely shot. Have you checked the pressure with a real gauge though?
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Old Mar 22, 2022 | 04:15 AM
  #24  
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Originally Posted by cruiser54
Cam bearings are likely shot. Have you checked the pressure with a real gauge though?
i am waiting for my gauge arrive off amazon today how do i check my cam bearings thanks for the help i will make it my mission to fix this ive only owned the car a few weeks feel like burning it already
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Old Mar 22, 2022 | 06:44 AM
  #25  
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From: Prescott, Az
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Engine: 4.0
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the engine has to come out and apart.
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Old Mar 22, 2022 | 07:10 AM
  #26  
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Originally Posted by cruiser54
the engine has to come out and apart.
so its had the head changed new oil pump bearings and seals checked new piston rings on a 2000 wj and now i have to take the engine out again really to check the cam bearings surely the garage would have checked this
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Old Mar 22, 2022 | 07:31 AM
  #27  
cruiser54's Avatar
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Test it first to verify the reading is correct. You can't SEE the cam bearings with the cam installed.
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