NAXJA Forums -::- North American XJ Association  

Go Back   NAXJA Forums -::- North American XJ Association > NAXJA Unibody Jeep Technical Forums > Jeep Cherokee XJ (1984 - 2001) > Modified Tech Discussion
HOME Member FAQ Sponsor Info Rules Bylaws E-Mail

Modified Tech Discussion Forum for Tech related discussion for Modified XJ's and MJ's.

Reply
 
Thread Tools Display Modes
  #1  
Old December 19th, 2019, 21:46
HotBox HotBox is offline
NAXJA Forum User
 
Join Date: Dec 2019
Location: NY
Posts: 20
Crank bearings?

After reading various threads I just wanted to get some definitive answers

I've got a 2001 XJ. Low oil pressure at hot idle. I am trying to cover all bases. Tomarrow I will be buying a mechanical gauge to test. With multiple different sending units it constantly dips to danger low and it trips the check gauges message


After reading it seems the consensus is the oil pump does little to nothing for the pressure. And it's more than likely the crank bearings. After confirming no crank in the head and no head gasket leak I'm assuming it's the bearings or pump (guessing the bearings over pump)

It's the original engine with 119k on it. My main question is how do-able is it to change the bearings while the engine is still in? I'm thinking of just doing everything at once because why not... oil pump, bearings, rear main, pan gasket


I'm sure this is the 100th time it's been asked but I still wanted to put it out there
Reply With Quote
  #2  
Old December 19th, 2019, 22:11
RCP Phx RCP Phx is offline
NAXJA Forum User
 
Join Date: Mar 2003
Location: Phoenix,Az
Posts: 13,024
Re: Crank bearings?

They are notorious for eating cam bearings also.
Reply With Quote
  #3  
Old December 19th, 2019, 22:18
HotBox HotBox is offline
NAXJA Forum User
 
Join Date: Dec 2019
Location: NY
Posts: 20
Re: Crank bearings?

Well shit... I had not considered cam bearings. And its so strange to think I have no knocking or loss of power. At this point Im hoping its nothing detrimental and the mechanical gauge test will come back with decent pressure

Starting this thread was just me trying to get my thoughts down and pick some brains who have possibly done this before and no resurrect any dead threads
Reply With Quote
  #4  
Old December 19th, 2019, 22:49
md21722 md21722 is offline
NAXJA Member
 
Join Date: Feb 2014
Location: Colorado
Posts: 2,426
Re: Crank bearings?

2000-2001 model years had 0331 heads which were known to crack between the 3-4 rocker arms and dump raw coolant into the oil. Coolant as little as 1-2% in oil is highly corrosive to bearings and will "wash" them causing low oil pressure. Cam and crank bearings should be highly suspect and replacing them may cost more than replacing the motor (or vehicle). Pulling a cam out of the 4.0 involves removing everything in front of the timing cover (radiator, condenser, etc) or removing the engine from the vehicle...
Reply With Quote
  #5  
Old December 20th, 2019, 07:13
HotBox HotBox is offline
NAXJA Forum User
 
Join Date: Dec 2019
Location: NY
Posts: 20
Re: Crank bearings?

I just did an oil change last week and aee so evidence of coolant in the oil. I haven't taken the valve cover off since it's not leaking (miracle) but the oil pan gasket does seep pretty good.

I've had a few XJs in the past and never had this problem with the oil press. Even my 06 LJ has 40 psi and it's just about to roll over 276k miles so... even though I'm very familiar with working on these engines I dont really know where to go from here
Reply With Quote
  #6  
Old December 20th, 2019, 07:18
HotBox HotBox is offline
NAXJA Forum User
 
Join Date: Dec 2019
Location: NY
Posts: 20
Re: Crank bearings?

Quote:
Originally Posted by HotBox View Post
I just did an oil change last week and aee so evidence of coolant in the oil

**** I see no evidence of coolant in the oil. *****
Reply With Quote
  #7  
Old December 20th, 2019, 12:07
Evan03 Evan03 is offline
NAXJA Forum User
 
Join Date: Jun 2017
Location: Idaho
Posts: 136
Re: Crank bearings?

It's not terribly hard to pull motor. Seems like it would be a pain to in the vehicle.

I think I'd pull valvecover and physically see the oil moving on head while it's hot and sensors are tripping. It may m as ke a mess running with valve cover off. But maybe not. My Cummins makes 40 and doesnt spray oil off the head while running but its also moving alot more volume

I'd be tempted to look at oil pressure sending unit. It may itself get hot and mess up.

If pressure is actually low after checking with mechanical gauge I'd probably dump oil and refill with hygard or Chevron thf1000 tractor transmission/hydraulic fluid.
Run it for 50 or 100 miles these oils are high in detergents and antioxidants theyl clean crap out of the system moisture.
These oils alone may bump oil pressure but I wouldn't run them long term because they also have friction modifiers.

I've cleaned some filthy motors out and am probably getting carried away thinking this way because your motor is low mileage.

Its probably something simple like a sending unit or passage plugged. With so low miles I'd try and not invest to much time in rebuilding.

But on that note if I was pull it to change all bearings I dont think I could reinstall unless I also did rings too


Good luck
Reply With Quote
  #8  
Old December 20th, 2019, 14:17
old_man's Avatar
old_man old_man is offline
NAXJA Member
 
Join Date: May 2003
Location: Loveland, Colorado
Posts: 15,734
Re: Crank bearings?

What oil are your running? What is the hot idle pressure? Was it checked with a manual gauge?

My bet is that you are running 5w30 synthetic. I set my engine up somewhat loose when I built it. It will hold 13psi with 10w30 at a hot idle. I run 15w40 Rotella and get 20+. I have put 250k+ on it and it is a 4.7L stroker.
__________________
Tom Houston - Former Colorado Chapter Treasurer , Terminal Adrenaline Junkie, and Rocket Scientist
Loveland, Colorado My teardrop build
You're just jealous because the voices don't talk to you.
Reply With Quote
  #9  
Old December 20th, 2019, 18:01
HotBox HotBox is offline
NAXJA Forum User
 
Join Date: Dec 2019
Location: NY
Posts: 20
Re: Crank bearings?

Evan.... I've thought about pulling the valve cover but haven't done it since it wasnt leaking. My most recent things done to the motor were the oil filter adapter o ring change, new sending unit and oil change. This was all last week. The sending unit I got was the one reccomend in other threads BWD brand I believe. My OEM sending unit was reading 5-10 psi at hot idle and around 25 at highway speeds. After changing the sending unit the new one reads lower than red line and around 35 psi at highway speeds

Again this is the first time I've ever dealt with a 4.0 having low oil pressure. I've never heard of running hydraulic oil, although I know that running trans fluid is an old school way to clean the engine so that's not so farfetched to me

The engine is low miles and I know the history of the engine as well so it's not been abused in its life. Very strange to me, but I haven't tested it with a mech. gauge yet. In upstate NY it's been around 10 degrees out for the last 2 weeks and Its hard to get motivated after getting out of work at 6... dark and cold with no garage sucks





Old man..... some of your questions were answered above but I can tell you about the oil I'm using. I've never used synthetic oil for any of my Jeeps. I'm running 10w40 in both my XJ and LJ. I've had a hard time finding 5w40 around me but I've always used 40w for years now. I never run any additives and this problem has just been a recent thing. I dont have any chatter from my valve train even with the 10w40 in the winter although I know switching to 5w40 is reccomend for my area of the country

I've always had around 20 psi hot idle and it slowly started dropping. Now with a new sending unit it redlines and when the rpms go up it will go up to around 35psi. I know these gauges can be unreliable so I fully intend to verify with a manual gauge
Reply With Quote
  #10  
Old December 20th, 2019, 19:49
devildog0's Avatar
devildog0 devildog0 is offline
NAXJA Member
 
Join Date: Apr 2005
Location: Hunt County Texas
Posts: 772
Re: Crank bearings?

Until you get a mechanical gauge on it or try swapping the sensor all we're doing is guessing. With pressure that low and no funky noises I'd be hard pressed to believe you have no pressure.
__________________
1995 XJ Country/4.0L/AW4/231/UpCountry Suspension
2004 Suzuki DL650 VStrom/1978 Suzuki GS1000E/2003 Yamaha TW200
1982 Suzuki GS850G (barnfind project)
Reply With Quote
  #11  
Old December 21st, 2019, 10:15
Hypoid's Avatar
Hypoid Hypoid is offline
NAXJA Member
 
Join Date: Jul 2006
Location: Golden, CO
Posts: 7,655
Re: Crank bearings?

What brand is the oil filter?
__________________
The Lost Boys' motto: We don't know where we are going, but we'll be there for awhile...
Reply With Quote
  #12  
Old December 21st, 2019, 18:21
HotBox HotBox is offline
NAXJA Forum User
 
Join Date: Dec 2019
Location: NY
Posts: 20
Re: Crank bearings?

STP brand part # S16XL. Usually go for the larger body filters
Reply With Quote
  #13  
Old January 6th, 2020, 12:42
HotBox HotBox is offline
NAXJA Forum User
 
Join Date: Dec 2019
Location: NY
Posts: 20
Re: Crank bearings?

Sorry to get back to this post late and thanks everyone for the replys

After checking with a mechanical gauge I found when the Jeep is first started it has 50psi. After about 5 minutes of running it goes down to about 30psi

After fully warmed up and sitting at idle I have only 12 psi

So it looks like even with a brand new sensor it was faulty because it was saying absolutely zero.

Went to Napa for a new sensor and the 2nd new one still reading zero. So I guess I'll be ordering one online and seeing how that goes. My OEM one I removed said I had 30psi at hot idle so that is the reason why I even changed it
Reply With Quote
  #14  
Old January 7th, 2020, 08:26
4x4JeePmaNthINg's Avatar
4x4JeePmaNthINg 4x4JeePmaNthINg is offline
NAXJA Forum User
 
Join Date: Nov 2008
Location: Colorado
Posts: 1,263
Re: Crank bearings?

I would not call 30 psi at idle low. I forget what the acceptable psi range is for hot idle but 30 iirc your just fine.
use a mopar sensor and if your stock sensor was working put it back, as long as its not reading zero.
Reply With Quote
  #15  
Old January 7th, 2020, 08:54
HotBox HotBox is offline
NAXJA Forum User
 
Join Date: Dec 2019
Location: NY
Posts: 20
Re: Crank bearings?

No I would love it if it was 30psi. That's while the engine is still warming. After driving and fully warmed up it drops to 12psi

I heard for every 1000 rpms its supposed to be 10 psi

So if I idle at 600 rpms it's fine to have 10psi. And at 2000 rpms I have more than 20 psi so I seem to be in specs. The hot idle at 12psi had me concerned because I've never had a 4.0 with such low pressure before. But after posting here and reading others experiences it seems XJs do have low pressure sometimes
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Gear set up great with set-up bearings, but can't fit pressed bearings back in housin thebyus Modified Tech Discussion 10 August 31st, 2015 07:34
Rear Main Seal - Crank Bearings djblade311 OEM Tech Discussion 4 November 2nd, 2010 18:30
Crank crank crank crank crank vroom gone postal OEM Tech Discussion 27 November 25th, 2006 10:47
crank-crank-crank-crank-cra... [wait...] crank-crank-START! iBran OEM Tech Discussion 20 October 21st, 2005 18:33
Rear wheel bearings (axle bearings) desertjeeper OEM Tech Discussion 5 July 13th, 2004 20:07


All times are GMT -7. The time now is 04:56.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
NAXJA and NAXJA logo's Copyright NAXJA. All content/images Copyright NAXJA 1999-2014