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Unread 10-10-2009, 04:49 PM   #1
yjjustforme
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oil pressure fluctuating

hey guys i got a ?. In the morning i start the jeep and the oil pressure guage reads like 60 and everything is fine and dandy. its when i have been driving it around for a while and the engine is warmed up and its warm outside that the guage will drop to around 40 or lower while idling. do u guys think its the oil pressure sending unit? if so i should just be able to do a quick swap of the "faulty" one right. (its right above the oil filter right?). thanks in advance.
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Unread 10-10-2009, 05:26 PM   #2
tobias94yj
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mine does that too. maybe it is a problem but I attribute it to the fact that once the oil warms up it thins up some so when you drop back down to idle the oil pressure lowers
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Unread 10-10-2009, 05:44 PM   #3
DEERSLAYER94YJ
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you are correct the sending unit is right above the filter, all in all your looking at a $5 part that takes 2 min. to install, worth trying it in my opinion.
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Unread 10-10-2009, 06:47 PM   #4
wanabejeeper
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That is perfectly normal. Cold oil has a higher viscosity resulting in a higher pressure at cold start up. Once its warmed up it will drop. 40 at idle is pretty good pressure. Around 20 at idle is normal for high milage +100k.

Less then 10 at idle and you need to have a good look at your main bearings
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Unread 10-10-2009, 07:27 PM   #5
yjjustforme
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k thanks guys my odo says 183k but i have had larger sized tires for YEARS so i pretty sure its way off. also i heard its ok to run 10 40 oil in my jeep when it has that many miles.
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Unread 10-10-2009, 07:27 PM   #6
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Quote:
Originally Posted by tobias94yj View Post
mine does that too. maybe it is a problem but I attribute it to the fact that once the oil warms up it thins up some so when you drop back down to idle the oil pressure lowers
Same here.
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Unread 10-10-2009, 08:05 PM   #7
godzirra
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mine idles at about half untill i press the gas pedal then it stays at 80 but comes back down once i stop. it goes up and down depending on how much gas i give it
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Unread 10-10-2009, 08:09 PM   #8
Fhajad
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Mine sits higher while cold. But on really hot days and such, it'll idle at 20 then under load I'm always at 40.
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Unread 10-10-2009, 08:14 PM   #9
yellow2kgt
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That is normal. Once the oil is warmed up the oil pressure should drop some at idle. As long as the pressure builds along with the RPMs you are fine. One of the local engine builders told me many years ago that as long as you have about 10 psi per 1000 RPM all is good. This is coming from a Ford guy that mainly builds race engines.
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Unread 10-10-2009, 09:27 PM   #10
XsaltlifeX
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Normal, don't worry at all!! Mine does the same thing!
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Unread 10-10-2009, 10:05 PM   #11
4.7stroker
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Normal,
In 96 the Mustang changed from a "real" guage to a guage that is nothing more than an idiot light wih a needle. People wouild see the guage moving and think that there was a problem then head off to the dealer so then the dealer would have to convince the customer there was nothing wrong.

Dwayne
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Unread 10-10-2009, 10:27 PM   #12
plac
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my 93 with 70k miles idles at 65psi (cold), and normally stays at 60psi at all times.
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Unread 11-13-2010, 04:35 PM   #13
msfitnrtz
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Whew! this happened today and glad it might be normal although took a while for idle to finally level off. I will still monitor & look at changing the oil and sensor.

Love these forums!

Thank You!
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Unread 11-13-2010, 07:47 PM   #14
jay-h
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The thing to look for is a change in oil pressure behavior. All engines have their individual quirks.
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