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Low oil pressure at idle- 97 TJ


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#1 fishinambition

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Posted December 01 2006 - 7:01 PM

Sometimes drops to about 10 psi at idle. Stays at 40 while driving. The pressure was chronically low until I changed my oil. Oil pump? That can't be cheap.



#2 Darth Baiter

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Posted December 01 2006 - 7:49 PM

How many miles? Main crank/connecting rod bearings worn or knocking? Gage is accurate? You're reading back pressure or resistance to flow, engines tight and pumps pumping - high resistance. You figure out the opposite. Not sure how resistance through the oil filter impacts the equation, maybe someone else can chime in cause I think it does. Do you have less of a problem with new/fresh oil? Change oil filter brands lately? Run a higher weight oil?


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#3 fishinambition

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Posted December 02 2006 - 10:25 AM

145,000 miles. I change the oil about every 30,000 miles. The last change went further. I know I'm an idiot. No knocks.



#4 sea jay

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Posted December 02 2006 - 11:06 AM

If you are serious about the 30,000 mile oil change, I think the oil probably wore itself out, losing it's lubrication abilities and thus lowering the oil pressure. You're lucky you didn't have extensive engine damage.



#5 fishinambition

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Posted December 02 2006 - 11:12 AM

I'm afraid I am serious. I noticed an immediate improvement with the new oil, but it's still not back to normal. The mechanic said the oil filter could have clogged or the oil pressure switch was bad. If not, oil pump. I think it's the oil pump. Anyone change one of these? Is this a job that I'm better off hiring someone for? I'm pretty good with wrenches, but not interestes in a serious motor teardown. Anything that can be accomplished in less than a day is fine.



#6 CHUCK BRYAN

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Posted December 02 2006 - 11:27 AM

If you are correct and the intervile has been 30,000 that only 4 to 5 times the oil has been recycled VS 48 if it was done at 3000.
I can't imagin the SLUDGE that is lying in the oil pan by now. The oil filter is not the problem its the oil ports in the block that are restricted. (its probably like my arteries).
Are you sure its 30,000 not 3000?


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#7 fishinambition

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Posted December 02 2006 - 11:32 AM

The last 6 quarts went about 45,000. How do I clear the ports? I was thinking of running high detergent oil and changing very frequently for a while.



#8 bob m

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Posted December 02 2006 - 11:57 AM

If you went 45,000 without a filter change every 3 or 4 thousand miles, I would seriously think you could have major rod or main bearing dfamage, I am presently "restoring an 88 Wrangler that has 88,000 miles( only 10,000 in the last 11 years) that was used only for plowing our factory lot and chasing around and found the rod bearings shot. This is with 3000 mile oil and filter changes. Storm crankshaft grinders in Mt Vernon. ny. said that these cranks tend to wear sooner than most. Yours being newer, I would check with a crank guy in your area before I spent money on a quick fix that is in reality not.



#9 fishinambition

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Posted December 02 2006 - 12:03 PM

The 88 had the AMC 4.2 liter. Nonetheless, it's worth looking into. Thanks.



#10 CHUCK BRYAN

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Posted December 02 2006 - 12:06 PM

I agree with Bob. You are looking at an engine, even though it is still running and not making noise, that is in need of a major overhaul.
If the Jeep is in good working order droping in a Jasper rebuilt and getting a couple more years out of it could be the way to go.
It beats spending 17,000 for a new one.


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#11 fishinambition

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Posted December 02 2006 - 12:12 PM

Quadratec has engines rebuilt by ATK for about $2,000 with the core-trade. The only condition is that the core must turn 360 degrees. I dont wanna swap a motor in the cold!



#12 Triet

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Posted December 02 2006 - 12:13 PM

Lotta Jeep boards like Seafoam added to the oil to clean out sludge, course it means another oil change 100 later. Look it up on jeepforum jeepunlimited etc. It is cheaper than replacing the engine......


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#13 fishinambition

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Posted December 02 2006 - 12:21 PM

If it was major damage, would the symptoms be constant or intermittent? Right now the fluctuations are intermittent. Since the temperature drop last night, I noticed the pressure was lower than usual, but that may be coincidence.



#14 Crash82

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Posted December 02 2006 - 1:18 PM

May I ask why you went 30,000 miles on an oil change? Even with synthetic I only go 5k on my 04 tj. If you are lucky you will be replacing an oil pump, unlucky, a motor. If i were you I would replace the oil pump now, because even if you replace the motor its unlikely to come with a new oil pump. When you were going on these long stretches without new oil did you at least check the level?



#15 fishinambition

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Posted December 02 2006 - 1:25 PM

Extreme procrastination? I did check the level. Especially when the oil light came on . Sad part is, I consider myself a "car guy". The level was kept fairly good most of the time, though.
Where is the oil pump located? I thought is was an internal part of the motor.