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Discussion Starter · #1 ·
Just switched to synthetic oil in my '95 YJ, 2.5 Lt this week and my oil pressure has gone nuts. It goes all the way to 6 and looks like it's trying to climb higher but the gauge only goes to 6... Any ideas? The oil has been changed religiously every 6000 (or less depending on how much wheeling I did) KMs since new. When I let it idle, it drops back to 3, but as soon as I give it throttle, back up it goes... TIA

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How many km on the engine? It may be that the synth oil has freed up many of the deposits in the engine and they have plugged up the filter and or pump. Those would be my first two places to check.

Just my guess
Wes

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My XJ (95, 4.0L HO) did the same thing until I changed the pressure sensor. To check it, run the rig and take the handle end of a screwdriver and lightly rap the sensor...this of course being after you unplug the wiring to the sensor and clean it. I have a feeling that the sensor is going haywire and needs to be changed out.

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Phil M. - Kent, WA
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my gauge on my 98 4.0L does a similar thing.
had it to the dealer,they said exactly as wes
explained.they suggested cleaning the pump
screen and changing the filter.
they also said,"repeat as nessesary" so i
assume this is common?

cheers: eric

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Mine had about 82k miles on it when it went, so I figured that replacing it for a few bucks wasn't a bad idea. It worked.


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Phil M. - Kent, WA
95 XJ Sport w/Stuff
"Who cares about a list of crap, can you drive it?"
 

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Discussion Starter · #6 ·
Originally posted by Wes Rempel:
How many km on the engine? It may be that the synth oil has freed up many of the deposits in the engine and they have plugged up the filter and or pump. Those would be my first two places to check.

Just my guess
Wes

Thanks for the input, muchly appreciated! It has 107,000 KMs (I know, I know, a bit late to switch to synthetic, but figured because it always had regular changes and was flushed every year, it would be okay).

Thought about the pump, but if the pump/filter/screen was blocked wouldn't it lower the pressure? Think it's prolly the pressure sending unit. That seems to be the popular opinion on the 'net and with the guys in the club. It's not blowing oil back through anywhere, so the pressure can't be as high as it reads. I'll swap it out on Monday when the dealer opens and I can get the part (Crappy Tire doesn't stock it...). Again, thanks guys!



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Seriously, it's a PUSH strap...
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Before you jump to any conclusions, find a mechanical oil pressure guage and find out for sure where your pressure is. ( 3 on a Jeep guage is about 25psi on a mech. guage)

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My YJ did the same thing. We changed the pressure sending unit and it fixed the problem.

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Leanne
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Speaking of Oil Pressure.

What are considered to be nominal pressures for cold/warm and idle/1500RPM oil pressure on the canadian guage? (3 being the middle)

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The manual says it should not hit the red in the upper or lower bounds. Gotta love the manual.

I find mine is a little less than 3 when just sitting idling and gets up to the next bar or so past 3 when I am woking the engine.
I think the YJ gauges were designed to have the needle point almost straight up when in the regular operating range.

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I compared the oil pressure gauge and found that the 3 is equal to 50 P.S.I. My gauge goes up to 5.4 which is like 80 lbs. Normal idle pressure is about 3 (45-50 lbs)in my 4.0 L. (192,000 kms) make the old girl work and it'll climb to about the 4 line, or what I guess to be about 60-65 P.S.I.
Buddy of mine has a YJ 4.0 L carb model, 212,000 kms and his oil pressure maxs right out, if it reads right hes got like 90-100 P.S.I !!!High is good.... but in moderation eh ;o)
Originally posted by Chris Epp:
Speaking of Oil Pressure.

What are considered to be nominal pressures for cold/warm and idle/1500RPM oil pressure on the canadian guage? (3 being the middle)

 

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Where did you get the comparison from? I just checked my service manual, and from the pictures, straight up (on a 94 YJ) is 3 for canadian, or 40PSI for US. The 3 must be in BAR (3 BAR is 44PSI) so that sounds about right.

According to the Service Manual, 40PSI is the MINIMUM for 1500RPM and 65PSI is the maximum (after that a relief valve is supposed to bypass the extra pressure).

So, if your at 1500 RPM, you should be at 3 or over...

Originally posted by murph992:
I compared the oil pressure gauge and found that the 3 is equal to 50 P.S.I. My gauge goes up to 5.4 which is like 80 lbs. Normal idle pressure is about 3 (45-50 lbs)in my 4.0 L. (192,000 kms) make the old girl work and it'll climb to about the 4 line, or what I guess to be about 60-65 P.S.I.
Buddy of mine has a YJ 4.0 L carb model, 212,000 kms and his oil pressure maxs right out, if it reads right hes got like 90-100 P.S.I !!!High is good.... but in moderation eh ;o)


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'94 YJ
 
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