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Post by Off_Road_Teacher on May 4, 2015 11:05:59 GMT -6
I bought an xj this past Saturday and it didn't appear to have any serious issues. The check engine light was on (evap leak- fixed it) and oil pressure gauge was reading 80. So I drove it home and picked up a cheap oil pressure switch from autozone to check it out. Put it in and at cold idle it was a tad above 40 but came down to about 25 after it got warmer. Decided to drive down the street and back, once I got back it dropped to 0 and it would rise each time I hit the gas. I took out the oil pressure switch and put in the old one.
Has anyone ever heard of this?
I'm thinking I need an actual mechanical gauge to give me a proper reading
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Post by Weezul on May 4, 2015 11:19:39 GMT -6
The OEM oil pressure gauge is just a dummy switch. It doesn't give accurate readings. Mine does what yours is doing all the time.
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Post by mike on May 4, 2015 11:20:40 GMT -6
I guess you've checked to be sure it's full.
In the old Chevys that would happen when the pickup tube fell off the oil pump but I think the 4.0 it's bolted in.
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Post by Off_Road_Teacher on May 4, 2015 11:25:42 GMT -6
Yeah I changed the oil yesterday and changed out that switch. I believe it's bolted on
Thats crazy though...
On the tj it was always a tad above 40 and never moved, this one is all over the place.
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Post by mike on May 4, 2015 11:47:02 GMT -6
The only way to know for sure is to put a mechanical gauge in it.
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Post by BEN on May 4, 2015 12:00:43 GMT -6
Put a real gauge on it even if it's just temp
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Post by Off_Road_Teacher on May 4, 2015 12:52:56 GMT -6
Ok thanks
I'll check it after school
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Post by Off_Road_Teacher on May 4, 2015 15:12:54 GMT -6
Well autozone sucks lol
We don't carry the oil pressure tool anymore
Bought the little mechanical gauge and got it all set up. Cranked it up and it read at 14 psi, never went below that but when given gas it rose to 30-35
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Post by 06blackmax on May 4, 2015 17:09:40 GMT -6
The factory guage in my YJ reads off the scale when cold then down to about 80 when at temp. The manual guage I installed for break in shown about 60 cold and 40 at temp.
14psi is not real good at idle, sounds like there's some bearing clearance issues going on. I think the guy you bought it from knew this and had real thick oil in it for the sale and you changed it out for the proper weight and now it shows low.
You can drop them pan and spin in new bearings and a new oil pump and not have to pull the engine. If the compression checks out and you have no blow by that might be an inexpensive alternative.
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Post by jeffreylane on May 4, 2015 17:31:40 GMT -6
MJL's was doing that in her old motor. Oil pump pickup was full of sludge when I dropped the pan. Popped in a new pump and primes it and pressure went back up to where it needed to be.
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Post by Off_Road_Teacher on May 4, 2015 17:48:20 GMT -6
MJL's was doing that in her old motor. Oil pump pickup was full of sludge when I dropped the pan. Popped in a new pump and primes it and pressure went back up to where it needed to be. Yeah I'll look into a new pump, what all has to be removed to drop that oil pan? I didn't really look and see if it's just like the wrangler Thanks |
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Just remember...we give them back in 10 months 
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