Author Topic: Any Jeep Fans?/Oil pressure prob  (Read 5422 times)

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Offline 1FSTLS1

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Any Jeep Fans?/Oil pressure prob
« on: August 23, 2008, 08:02:11 PM »
I got this Jeep for my wife heard the 6cyl was industructable. So I got low or no oil pressure at idle. Changed sending unit cleaned conectins new oil pump heavier oil ect. Seems like most people here are more ________ lets just say knowledgable. I need some opinions. here is my jeep post: http://www.jeepforum.com/forum/showthread.php?t=595475

I dont want to pull this motor I have too many other projects

1999 Silver Z28
1981


Offline eroc022

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Re: Any Jeep Fans?/Oil pressure prob
« Reply #1 on: August 23, 2008, 09:35:45 PM »
could be the oil pump? if the previous one failed, then it could happen again, not to mention if it is a typical metal gear pump and the previous pump was so bad that it sent metal through the oil then  your bearings could be worn causing for a drop in pressure.....
Eroc
Fixing the car that Restore A Muscle Car jacked up....

Offline Rarebird

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Re: Any Jeep Fans?/Oil pressure prob
« Reply #2 on: August 23, 2008, 10:41:59 PM »
question is.. are you going by the factory gauge or going by the indicator light.. my suggestion would hook up a test gauge to verify your pressure. if the gauge shows a differant reading then I would say your wiring is at fault.
  not familuar with the engine set up you have in your jeep....V6, Inline, if the sending unit is connected to a oil filter adapter plate.... had a Berratta GT that had the same problem.. changed sending unit, oil pump, crank, and it came down to the oil filter adapter plate had a gasket that had blown out and oil was by-passing when the engine got up to operating temp. changed the gasket and oil pressure went up to above normal ( installed high pressure pump ).
Virgil...
1978 W72 w/M21 T/A   

Offline 1FSTLS1

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Re: Any Jeep Fans?/Oil pressure prob
« Reply #3 on: August 24, 2008, 08:29:12 AM »
I have a mechanical gage hooke up and its a inline 6
1999 Silver Z28
1981


Offline 1973Formula

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Re: Any Jeep Fans?/Oil pressure prob
« Reply #4 on: August 24, 2008, 09:26:44 AM »
I do not have any 4.0 experience, but I have had a few 4.2L Jeep motors.  They all have low pressure at idle.  I would bet that the previous owner had the same problems hence the new pump and sending unit.  How is the pressure under normal driving conditions?  You are correct that the engines are "indestructible", however they do wear out.  I have seen some with over 200k and others that are done at 120k.  If you have decent pressure under normal driving conditions, I would switch to one of the High Mileage engine oils and drive it without worry.  I think it is functioning as designed considering the mileage.  Just be careful with it if you take it off-road.  My valvetrain clatters like crazy when idling on really steep inclines.

I am hoping my 73 Firebird project will turn out as well as my 82 Scrambler.


Offline 1FSTLS1

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Re: Any Jeep Fans?/Oil pressure prob
« Reply #5 on: August 24, 2008, 11:16:22 AM »
Oil pressure is as low as 20 while driving.  Around 1500-2000 RPM  Thinking about replacing the bearings.  I should be able to do it with the motor in the jeep
1999 Silver Z28
1981


Offline Rarebird

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Re: Any Jeep Fans?/Oil pressure prob
« Reply #6 on: August 24, 2008, 11:55:59 AM »
may be worth you while to inspect the journals very well one the mains and rods. if you have bearing wear chances are the journals are toast as well. IMO it would be insurance to change out the crank if you go that far.
Virgil...
1978 W72 w/M21 T/A   

Offline jphillips3333

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Re: Any Jeep Fans?/Oil pressure prob
« Reply #7 on: August 24, 2008, 01:47:46 PM »
I'd add 70 weight oil, perhaps a few more additives as you've done before ripping into it.

Drop the pan - is the pickup loose/skewed?  I typically have those brazed onto the oil pump before installing.

I had a 79 Z28 with a B&M blower//350 running 20 PSI @ idle.  Scared me every time I looked at it.  I drove it.  Hard.  It never failed for over 10K miles back in the day.  Then I moved to CO, left it in FL and it sold.
John

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Offline eroc022

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Re: Any Jeep Fans?/Oil pressure prob
« Reply #8 on: August 24, 2008, 04:38:14 PM »
Oil pressure is as low as 20 while driving.  Around 1500-2000 RPM  Thinking about replacing the bearings.  I should be able to do it with the motor in the jeep

honestly i would hold off doing anything till its offcially dead, oil pressure is a good thing, as long as you have pressure its showing that everything is getting oiled, when it drops to nothing and you hear it thats when you have a problem....remember its a fraction of an inch that the oil takes up in bearings and whatnot....so as long as you have a constant pressure id keep on gettin it
Eroc
Fixing the car that Restore A Muscle Car jacked up....

Offline 1FSTLS1

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Re: Any Jeep Fans?/Oil pressure prob
« Reply #9 on: August 27, 2008, 12:49:40 PM »
Well I am going to replace main and rod bearings whille im in there.  Do I need lock tight when I put the main bolts and rod bolts back on?  I also found some sludge on the pickup screen.  Clearance was good on 2 of the main bearings I have not got any farther yet.  Keep in mind the motor is still in.
1999 Silver Z28
1981


Offline eroc022

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Re: Any Jeep Fans?/Oil pressure prob
« Reply #10 on: August 27, 2008, 02:30:15 PM »
do your bearings look like there is any scarring at all? if so that means they are shot, they should be really smooth, as well as the crank should look like high polished metal...no lock tight just put the proper torque on them and you should be good.....
Eroc
Fixing the car that Restore A Muscle Car jacked up....