SUDDEN oil pressure drop
02-15-2013, 08:10 PM
#1
Seasoned Member
Thread Starter
Join Date: Jan 2012
Location: Yuma, AZ....yes the 3:10 came here
Posts: 433
Likes: 0
Received 1 Like
on
1 Post
Year: 1998
Model: Cherokee
Engine: 4.0
SUDDEN oil pressure drop
Use the search function....I know but I'm mid divorce money's tight got a 2 year old running around and my patience is thin, so I really don't feel up to it at the moment and I don't really have the free time.
So I've had perfect oil pressure consistently and changed the oil one month ago and it was good then. And today all of a sudden it dropped to 10psi and about 35psi at 2,000 RPMs. I know the general causes of low oil pressure but I was wondering if there was a usual suspect specifically for the 97+ 4.0 4x4 Cherokees. Any help would surely ease my tension if even the tiniest amount.
Also I noticed a whistle noise that's only in drive, not neutral or park, when I'm accelerating. It's coming from the lower left (driver) side. I checked the torque on my intake manifolds and headers and all is good. Sprayed starter fluid around intake and TB and no rise in rpm. I can not make it whistle in park or neutral ONLY in drive. It started about a month ago when I put the K&N filter in the stock air box (box is sealed tight no leaks) Possibly linked to the oil pressure?
1998 XJ 4x4 4.0
98,xxx miles
K&N filter
Headers
Flow master super 40
4.5 lift
33x12.5
So I've had perfect oil pressure consistently and changed the oil one month ago and it was good then. And today all of a sudden it dropped to 10psi and about 35psi at 2,000 RPMs. I know the general causes of low oil pressure but I was wondering if there was a usual suspect specifically for the 97+ 4.0 4x4 Cherokees. Any help would surely ease my tension if even the tiniest amount.
Also I noticed a whistle noise that's only in drive, not neutral or park, when I'm accelerating. It's coming from the lower left (driver) side. I checked the torque on my intake manifolds and headers and all is good. Sprayed starter fluid around intake and TB and no rise in rpm. I can not make it whistle in park or neutral ONLY in drive. It started about a month ago when I put the K&N filter in the stock air box (box is sealed tight no leaks) Possibly linked to the oil pressure?
1998 XJ 4x4 4.0
98,xxx miles
K&N filter
Headers
Flow master super 40
4.5 lift
33x12.5
02-15-2013, 08:25 PM
#3
Seasoned Member
Thread Starter
Join Date: Jan 2012
Location: Yuma, AZ....yes the 3:10 came here
Posts: 433
Likes: 0
Received 1 Like
on
1 Post
Year: 1998
Model: Cherokee
Engine: 4.0
Oh and I added one bottle of Lucas stop leak because the rear main seal leaks about the size of a half dollar puddle a day.
02-15-2013, 10:10 PM
#6
Newbie
Join Date: Nov 2012
Location: Utah
Posts: 31
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1999
Model: Cherokee
Engine: 4.7 stroker
Well, i asked because stop leak stuff is supposed to fill in holes to stop leaks. All your oil passages are holes that can be plugged by that stuff. Im thinkin it could have built up in front of the oil pressure sender, which would make it read low and starve the rest of the motor for oil. If it was after it would read high. If you added it before more than once, and your still using it, it doesnt seem like its workin, so if it were me, i would change the oil again without that stuff. Before you change it, drain a little out and replace it with seafoam or atf for a short time to clean it out. Then use a good napa gold or wix filter and see what the pressure does.
02-15-2013, 10:54 PM
#7
Seasoned Member
Thread Starter
Join Date: Jan 2012
Location: Yuma, AZ....yes the 3:10 came here
Posts: 433
Likes: 0
Received 1 Like
on
1 Post
Year: 1998
Model: Cherokee
Engine: 4.0
Well, i asked because stop leak stuff is supposed to fill in holes to stop leaks. All your oil passages are holes that can be plugged by that stuff. Im thinkin it could have built up in front of the oil pressure sender, which would make it read low and starve the rest of the motor for oil. If it was after it would read high. If you added it before more than once, and your still using it, it doesnt seem like its workin, so if it were me, i would change the oil again without that stuff. Before you change it, drain a little out and replace it with seafoam or atf for a short time to clean it out. Then use a good napa gold or wix filter and see what the pressure does.
Trending Topics
02-15-2013, 11:26 PM
#8
CF Veteran
Join Date: Apr 2009
Posts: 4,734
Likes: 0
Received 9 Likes
on
9 Posts
Year: 2015, 2012
Model: Grand Cherokee (WK2)
Engine: 3.6L
You're going to have to verify the oil pressure is actually low, and not a gauge or sender problem.
Plumb a mechanical gauge into it for a process of elimination.
On a side note, I personally have never been a big fan of oil additives or "fix-it-in-a-can".
Plumb a mechanical gauge into it for a process of elimination.
On a side note, I personally have never been a big fan of oil additives or "fix-it-in-a-can".
02-16-2013, 06:37 AM
#9
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,863
Received 1,524 Likes
on
1,236 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Probably not even the RMS anyway.
Try this:
I'd be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.
Everybody, who doesn't own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking.
Many mechanics, friends, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it?
A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don't jump on the RMS/oil pan gasket bandwagon right off the bat.
Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons.
First off, the engine sits nose-up and any oil will run back to the RMS area. Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber's adage apply here. "$hit flows downhill".
Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first.
Revised 9-15-2012
Try this:
I'd be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.
Everybody, who doesn't own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking.
Many mechanics, friends, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it?
A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don't jump on the RMS/oil pan gasket bandwagon right off the bat.
Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons.
First off, the engine sits nose-up and any oil will run back to the RMS area. Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber's adage apply here. "$hit flows downhill".
Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first.
Revised 9-15-2012
02-16-2013, 07:20 AM
#10
CF Veteran
Join Date: May 2012
Location: Lost in the wilds of Virginia
Posts: 7,964
Received 951 Likes
on
767 Posts
Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
Yes. All of this.
If I had an engine that was pretty much shot, and I knew it (leaking like a sieve, poor compression), but I had to get it to keep running a bit longer, I'd probably toss in some Lucas.
For a half-dollar sized puddle on an otherwise good engine?
No way would I put that stuff in my engine!
02-16-2013, 10:18 AM
#12
CF Veteran
Join Date: Sep 2009
Location: ☼ Blackhole Sun
Posts: 8,567
Likes: 0
Received 18 Likes
on
16 Posts
Year: My Jeep is a GMC
91 octane, Lucas, it's no wonder you are broke, lol. Verify the oil pressure actually is low, the factory gauges are not known for accuracy. After that dump the Lucas in the trash and stick with regular fuel (your 4.0 can't really tell the difference anyway).
02-16-2013, 03:05 PM
#13
Seasoned Member
Thread Starter
Join Date: Jan 2012
Location: Yuma, AZ....yes the 3:10 came here
Posts: 433
Likes: 0
Received 1 Like
on
1 Post
Year: 1998
Model: Cherokee
Engine: 4.0
Probably not even the RMS anyway.
Try this:
I'd be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.
Everybody, who doesn't own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking.
Many mechanics, friends, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it?
A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don't jump on the RMS/oil pan gasket bandwagon right off the bat.
Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons.
First off, the engine sits nose-up and any oil will run back to the RMS area. Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber's adage apply here. "$hit flows downhill".
Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first.
Revised 9-15-2012
Try this:
I'd be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.
Everybody, who doesn't own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking.
Many mechanics, friends, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it?
A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don't jump on the RMS/oil pan gasket bandwagon right off the bat.
Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons.
First off, the engine sits nose-up and any oil will run back to the RMS area. Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber's adage apply here. "$hit flows downhill".
Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first.
Revised 9-15-2012
02-16-2013, 03:11 PM
#14
Seasoned Member
Thread Starter
Join Date: Jan 2012
Location: Yuma, AZ....yes the 3:10 came here
Posts: 433
Likes: 0
Received 1 Like
on
1 Post
Year: 1998
Model: Cherokee
Engine: 4.0
I'm pretty sure it's not, because if it were the filter in itself it would whistle no matter what. This whistle is only in drive on acceleration. Not neutral. Not park. Not idle. Not decelerating. I checked the seal all is tight so no leaks either. And the whistle is definitely lower in the engine bay than the air box.