Oil Pressure drop, DD need help quick! - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ Tech Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 02-21-2009, 10:11 AM   #1
Jeeper
 
Join Date: Feb 2009
Location: Connecticut
Posts: 92
Cool Oil Pressure drop, DD need help quick!

OK, I took a 2 hour trip up the highway, half way there we made a pit stop. While everyone ran in to BK, I sat out in our 4.0 2000 TJ, engine running when I noticed the Check Guages light, as I scanned the guages I saw I had little or no oil pressure. I shut it off while I waited for everyone and started it back up, initially I had about 20lbs, as I drove and the rpm's went up the pressure went up, I pulled into a gas station, checked the oil and I was down a quart, so I added it. Started up and hit the highway. On the highway at around 1,700 rpm's I have about 30-35 lbs, normally 40. As soon as I pulled off the highway and stopped at the light, the pressure slowly dropped to about 10lbs, then to about 5, then it dropped, free fall to the bottom and the check guages light came on. I tacked it up a bit and the pressure came back up and the light went out.

Bottom line, while driving I have pressure 30 - 35 where it used to be around 40, when I stop, it drops. After being out of the Jeep for a couple of hours, I start it up cold and the pressure is up there, as soon as it warms up it drops. Even at idle with the guage bottomed out, I hear no lifter noise or anything out of the ordinary. If this is a standard oil pump, I find it odd it would all of a sudden let go, a friend said I may have something caught in the by pass spring, reducing the pressure, or could it be the guage or sending unit?

Needless to say, it's kind of unerving driving like this, any ideas? It's my DD so I have to figure it out.

Thanks
__________________
Todd Green
Bethany, CT 06524 U.S.A!

Jeep - http://www.flickr.com/photos/9834165...7601422585248/

Latest Jeep 1/09 - http://www.flickr.com/photos/9834165...7606985472720/

Chevelle - http://www.flickr.com/photos/9834165...7601617779453/

Bronco - http://www.flickr.com/photos/9834165...7603908320040/

Under the Palms is offline   Quote Quick Reply
Old 02-21-2009, 10:53 AM   #2
Jeeper

WF Supporting Member
 
first timer's Avatar
 
Join Date: Dec 2008
Location: lawrence kansas
Posts: 71
oil pressure

start with sending unit it is less costly than pulling oil pan also how many miles on motor,has it always had proper maintance done on time?

first timer is offline   Quote Quick Reply
Old 02-21-2009, 12:19 PM   #3
Jeeper
 
Join Date: Aug 2008
Location: Central Va.
Posts: 51
Hey Under the Palms,

I have a '97 Sport the did the exact same thing. Scared the heck out of me when I first bought it. Replaced the sending unit and it helped for a couple of days then back to the same thing.
I installed a mechanical guage inline with a T-fitting and and now I can see the real oil pressure.
When the dash guage is running 40psi the mech. guage is running 55 to 60psi.and when the dash guage starts acting up again I'm still running the same psi.

These guages in the early Tj's are famous for being incorrect but you might want to get it checked out or install a mechanical guage like I did.

Best of Luck,
Tim
rookiejeeper is offline   Quote Quick Reply
Old 02-21-2009, 04:57 PM   #4
Newb
 
Join Date: Feb 2009
Posts: 2
same experience

I have the same exact problem with my 97 TJ. I replaced the sending unit and also was running a secondary gauge just to make sure, and after several thousand miles of no extreme pressure drops I have decided to ignore the stock gauges.

Quote:
Originally Posted by rookiejeeper View Post
Hey Under the Palms,

I have a '97 Sport the did the exact same thing. Scared the heck out of me when I first bought it. Replaced the sending unit and it helped for a couple of days then back to the same thing.
I installed a mechanical guage inline with a T-fitting and and now I can see the real oil pressure.
When the dash guage is running 40psi the mech. guage is running 55 to 60psi.and when the dash guage starts acting up again I'm still running the same psi.

These guages in the early Tj's are famous for being incorrect but you might want to get it checked out or install a mechanical guage like I did.

Best of Luck,
Tim
TonkaTJ is offline   Quote Quick Reply
Old 02-21-2009, 05:25 PM   #5
Jeeper
 
Join Date: Mar 2008
Location: outside of Juneau Alaska
Posts: 102
there is no stock oil pressure gauge in a TJ.

there is a gauge that pretends to be one though.
the one in the dash is NOT an actual oil pressure gauge. it is a simulated gauge that is run by the computer as there is no oil pressure sensor on the engine. there is only an oil pressure switch that says you have oil flow or you dont.

if you want to see your actual pressure you have to install a mechanical pressure gauge.
__________________
94 cummins w/dodge2500, 260 injectors,191 DV, BHAF, #10 plate, 45lb boost!
03 rubi cherry bombed, rokmen merc. 5.5" RKLA, TW shaft, Bilstein shocks, 35" TOYO mt, jks 1" mml/bl, xd9000i, yaesu 8800r/diamond SG-7500, rock lights, HID lights, KC lights, some other stuff
IF THE SMOKE AIN'T BLACK, TAKE IT BACK
Little tin, Little board, put together you have a ford
sean42069 is offline   Quote Quick Reply
Old 02-23-2009, 04:18 PM   #6
Jeeper
 
ATL Rubi's Avatar
 
Join Date: Aug 2008
Location: Suwanee, Ga
Posts: 18
Send a message via AIM to ATL Rubi
My Jeep is doing the EXACT same thing now. Sunk it in some mud a couple months ago. Got around to fixing it yesterday.

Pulled the oil pan, Replaced the main and rod bearings. I found that I spun the rod bearings for cylinders 1-3 and DESTROYED the bearing in 1. Well I got it all put back together and it does the exact same thing as UnderThePalms. 40psi cold, then 0-5psi when it is hot. My problem might be excessive clearance between the crankshaft journal and rod bearings from where I slowly ground down the crankshaft. But what would cause this anyway? Clogged crankshaft oil jounals?

I am using a mechanical gauge.

, sorry

Somebody Please Help. It sounds like we have the same problem.
__________________
2004 Patriot Blue Rubicon, XRC-8 Winch and U-Pol Raptor tub liner are in the mail.

Want list: 33x10.50x16 M/T's, a little lift, JKS Quicker Disconnects, Biggest poser stinger that I can find, and skid plates

God, please give us strength and health; We'll steal the rest.
ATL Rubi is offline   Quote Quick Reply
Old 02-23-2009, 04:21 PM   #7
Jeeper

WF Supporting Member
 
first timer's Avatar
 
Join Date: Dec 2008
Location: lawrence kansas
Posts: 71
Smile gauge

most all cluster gauges that are stock in vehicle are just indicators not true reading gauges-if you want exact you must use manual gauges.
first timer is offline   Quote Quick Reply
Old 02-23-2009, 11:01 PM   #8
Jeeper
 
jeepjeep's Avatar
 
Join Date: May 2008
Location: west palm beach , fl
Posts: 149
Send a message via AIM to jeepjeep
same problem here also , i just rolled 30k on my 06 x, but i think my problem comes from a high running temp(225 while wheelin) causing the oil to thin out. but good luck!!i would pull out the sending unit, then thread in a manual guage see what readings you get cold/hot /idle etc.
__________________
'06 X 6spd...

milemarker 8k,junkyard lift w/ skyjacker nitro shocks,smitybuilt bumper, kc daylighters, auburn ected d30, 34" swampers, new project dana44 hp and 9" axle swap with 4.88/locked f/r , new new project full traction 6" long arm...
jeepjeep is offline   Quote Quick Reply
Old 02-24-2009, 01:29 PM   #9
Jeeper
 
Twozerofd's Avatar
 
Join Date: Jan 2009
Location: Suffern, NY
Posts: 296
Anyone have a write-up on how to put in a mechanical oil pressure gauge??
__________________
I got 99 Problems but a Jeep ain't one
Twozerofd is offline   Quote Quick Reply
Old 02-24-2009, 07:33 PM   #10
Jeeper
 
03rubi's Avatar
 
Join Date: Dec 2007
Location: Colorado Springs
Posts: 121
To install a manual guage you will need to remove the oil pressure sender on the passenger side of the 4.0 liter engine and install a T fitting in the port. I believe it is 1/4" pipe. Then run a of 1/8" copper or plastic line to a guage mounted in the location of your choice using a 1/8" compression fitting on the back of the guage. There may even be a kit available at the local parts store. Check around. To put your mind at rest, this is a common problem on early TJ's and you will find that the factory oil guage back then was notoriously inaccurate especially at idle. My 97 would often go below 10 psi. at idle on a warm engine according to the factory guage, but the mechanical guage would read double that. The mechanical guage will be the more accurate of the two so trust it, just don't buy a really cheap guage.
03rubi is offline   Quote Quick Reply
Old 02-24-2009, 08:29 PM   #11
Knows a couple things...

WF Supporting Member
 
Jerry Bransford's Avatar
 
Join Date: Nov 2005
Location: Escondido, Calif.
Posts: 32,803
Images: 2
Whether or not the TJ's gauges are accurate or just a simple "yep the pressure's ok" kind of a guage depends on the model year of your TJ. Older TJ gauges like in my '97 TJ are right on the $$$, newer gauges really only show a relative oil pressure.

To have a very accurate gauge, you're more likely to have it read dead-on accurately if you go with an aftermarket electric sender and gauge kit like from Stewart Warner or Autometer rather than a mechanical gauge with an oil tube connected to the gauge. The aftermarket sender and gauge type are generally right on the money. Purely mechanical gauges have more variables affecting their accuracy such as the possibility of air in the line, kinks in the line, etc.

But for the OP, I would simply replace the sender first to see if that cures the issue. That would be simple, cheap, and easy. The factory gauge provides a good enough indication for 99% of us. If not, then possibly you have an oil pump or engine problem.
__________________
When you have a choice, buy American.

Jerry Bransford is offline   Quote Quick Reply
Old 10-04-2010, 04:05 PM   #12
Newb
 
Join Date: Oct 2010
Posts: 1
oil pressure indicator jump up and down

Quote:
Originally Posted by Under the Palms View Post
OK, I took a 2 hour trip up the highway, half way there we made a pit stop. While everyone ran in to BK, I sat out in our 4.0 2000 TJ, engine running when I noticed the Check Guages light, as I scanned the guages I saw I had little or no oil pressure. I shut it off while I waited for everyone and started it back up, initially I had about 20lbs, as I drove and the rpm's went up the pressure went up, I pulled into a gas station, checked the oil and I was down a quart, so I added it. Started up and hit the highway. On the highway at around 1,700 rpm's I have about 30-35 lbs, normally 40. As soon as I pulled off the highway and stopped at the light, the pressure slowly dropped to about 10lbs, then to about 5, then it dropped, free fall to the bottom and the check guages light came on. I tacked it up a bit and the pressure came back up and the light went out.

Bottom line, while driving I have pressure 30 - 35 where it used to be around 40, when I stop, it drops. After being out of the Jeep for a couple of hours, I start it up cold and the pressure is up there, as soon as it warms up it drops. Even at idle with the guage bottomed out, I hear no lifter noise or anything out of the ordinary. If this is a standard oil pump, I find it odd it would all of a sudden let go, a friend said I may have something caught in the by pass spring, reducing the pressure, or could it be the guage or sending unit?

Needless to say, it's kind of unerving driving like this, any ideas? It's my DD so I have to figure it out.

Thanks
__________________
Todd Green
Bethany, CT 06524 U.S.A!

Jeep - http://www.flickr.com/photos/9834165...7601422585248/

Latest Jeep 1/09 - http://www.flickr.com/photos/9834165...7606985472720/

Chevelle - http://www.flickr.com/photos/9834165...7601617779453/

Bronco - http://www.flickr.com/photos/9834165...7603908320040/
Same problem with me
cobra is offline   Quote Quick Reply
Old 10-04-2010, 04:56 PM   #13
Jeeper
 
rubicon hobby's Avatar
 
Join Date: Sep 2010
Location: Fort Myers FL
Posts: 90
You can read my post on low oil pressure at idle as well if you want. It looks like this is a common problem.

rubicon hobby is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Low oil pressure at idle 97tjcse TJ Tech Forum 9 08-24-2009 11:12 PM
Tire Pressure scotiez General Jeep Discussion 15 04-08-2008 06:35 PM
T-case drop removal GrnTJ TJ Tech Forum 5 10-01-2007 06:30 PM
Oil pressure drop coyote99 TJ Tech Forum 5 09-25-2007 06:58 AM
oil pressure drop mark TJ Tech Forum 2 10-17-2006 12:08 PM



Download our Mobile App

» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 07:04 AM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC