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Oil pressure dropping to less than 20

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Old 11-14-2013, 10:49 PM
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Default Oil pressure dropping to less than 20

Time for a new oil pump? Dang thing is running at just over 40 until it gets hot, then it drops to 20 at cruise. Come to idle and the pressure is a little over 15.

I have a new pump on the way, is there something else I should be looking for/at?

The old girl has 223 on the clock.
Old 11-15-2013, 05:42 AM
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Your within spec. What is your idle rpm? What is pressure at 2000rpm? What is engine temperature? What type of oil + filter? It does not sound like you have a problem.
Old 11-15-2013, 06:11 AM
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I'd verify the actual pressure with a mechanical gauge before proceeding.

I'm curious also about what brand of oil filter you're currently using.

Pull the wire off the oil sender. Is it oily in there?
Old 11-15-2013, 09:47 AM
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Pull the oil sender off and run a zip tie or pipe cleaner through it. Gunk builds up in there giving you an incorrect reading because as the oil gets hotter and thins out, it looses its ability.to push through the gunk to get to the OPSU. THEN check it with a, mechanical guage.

Odds are, your fine. Min oil pressure spec is 13psi according to the FSM and many other sources. Mine has been running at that for 2 years with no problem. But still do what i said before. Be careful not to mess up the OPSU when removing it to do the pipe cleaner or ziptie, the littlest bump messes them up. I have big hands and i already wrecked 3 when changing my oil
Old 11-15-2013, 11:24 PM
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I believe that the sending unit is accurate.

I replaced it because I didn't like the reading. and it is reading basically the same. Also, I had that leak around the oil filter adapter and leaked half of my oil out over two weeks. When I went around a corner, the needle hit "zero" and the valves started clattering. Despite replacing the o-rings, the oil pressure does the same 'fade" as the engine hits operating temp.

No clatter, but I suspect a stuck/worn pressure bypass.

Oil is 10/30 like always. Filter is new. Oil is new. this pressure issue is also new.

ETA: The engine runs at 210 always. No oil around the sender, nor under the cap.

Last edited by rangermonroe; 11-15-2013 at 11:27 PM.
Old 11-16-2013, 04:50 AM
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Originally Posted by Ye Ol' Cherokee
the oil gets hotter and thins out, it looses its ability.to push through the gunk to get to the OPSU. l
I gotta say no. My oil, thin, or thick pushes through when ever I want.

Go to Rotilla 15-40 with a Napa gold, same as Wix) filter, and don't worry about the gauge.

OK, you didn't fill out your info. If you are in Ice, North Dakota that might not be the correct oil.

Last edited by DFlintstone; 11-16-2013 at 05:01 AM.
Old 11-16-2013, 05:00 AM
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Originally Posted by bigbadon
Your within spec. What is your idle rpm? What is pressure at 2000rpm? What is engine temperature? What type of oil + filter? It does not sound like you have a problem.
Old 11-16-2013, 05:07 AM
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Originally Posted by cruiser54
Pull the wire off the oil sender. Is it oily in there?
I'd listen to Cruiser and fill out my info.
Old 11-16-2013, 09:22 AM
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What BRAND of oil filter? This only started since an oil change?
Old 11-17-2013, 06:14 PM
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No, it didn't start with an oil change.

I have replaced the OPSU as I suspected that it might be the culprit. It reads the same as the old one.

The oil leak around the adapter started at the last oil change, but has been rectified.

The pressure was running steady at 40+/- 5 and then started the wild swinging.

It drops to "gauge" zero after the engine is warm at idle, but hits about 25psig while running.

Despite reading "zero" there is no valve clatter.
Old 11-17-2013, 06:22 PM
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Since Cruiser has already asked a couple of time and You won't answer the simple question I figured I would give it a try... What brand of filter are you using? Since a crappy filter can make a big difference on your pressure reading. Also have you tried to clean it the hole for the oil sending unit. I'm not talking about on the sending unit but the hole in the block.
Old 11-17-2013, 06:40 PM
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Originally Posted by RTorrez1
Since Cruiser has already asked a couple of time and You won't answer the simple question I figured I would give it a try... What brand of filter are you using? Since a crappy filter can make a big difference on your pressure reading. Also have you tried to clean it the hole for the oil sending unit. I'm not talking about on the sending unit but the hole in the block.
Mr. Torrez: Thanks for noticing. Not addressing the oil filter issue and not diagnosing using a mechanical gauge, we are in a conumdrum, aren't we?
Old 11-17-2013, 06:50 PM
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Originally Posted by cruiser54
Mr. Torrez: Thanks for noticing. Not addressing the oil filter issue and not diagnosing using a mechanical gauge, we are in a conumdrum, aren't we?
We sure are!
So many people wanting help but they want to keep things to them self. The small thing like a filter can make a big differance and they can seem to understand that. Or they don't want to verify the pressure. They would rather start throwing parts at it then they wonder why they can't fix it.
Old 11-17-2013, 06:53 PM
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Originally Posted by RTorrez1
We sure are!
So many people wanting help but they want to keep things to them self. The small thing like a filter can make a big differance and they can seem to understand that. Or they don't want to verify the pressure. They would rather start throwing parts at it then they wonder why they can't fix it.
Perhaps we should focus our energies elsewhere and let those who choose to stick their heads in the sand be victims of their own devices?
Old 11-17-2013, 06:58 PM
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Originally Posted by RTorrez1
Since Cruiser has already asked a couple of time and You won't answer the simple question I figured I would give it a try... What brand of filter are you using? Since a crappy filter can make a big difference on your pressure reading. Also have you tried to clean it the hole for the oil sending unit. I'm not talking about on the sending unit but the hole in the block.

+1 AGREE. The first step in diagnosing a problem is collecting data. Without data your just another person with an opinion.


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