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Old 03-30-2012, 07:54 AM   #1
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Default Oil Pressure Sending Unit

I have read through a bunch of previous threads, sounds like the sending unit is the culprit. Truck runs great, 5.0 engine, however the fake oil pressure gauge reades just on the right side of N of NORMAL. Sometimes it will jump up and sit right in the middle of O, and sometimes between N and O. From what I have read, this is a pretty common thing, and the gauge isnt really a gauge at all. However, its one of those things that you would like to see it back where I think it should be, just to the right of straight up and down. A new sending unit is super cheap, however the location of it looks to be a booger to get to. I am sure many of you have done this to your trucks, any suggestions that might make this easier? Does it require a "special" socket to remove the factory sending unit? Can just barely see the darn thing.. .havent tried from underneath, maybe that would be easier. Pretty sure thats what it is... just replaced my water temp sending unit, it was doing the same thing. Dont know why they ever put a "dummy gauge" in.. not much sense in that.
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Old 03-30-2012, 02:16 PM   #2
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If your truck is a 5.0L/302..........

They are cheap and very easy to remove to if you remove the oil filter. You will need a special socket to remove it or if you are handy with vice grip pliers, you may be able to get it off by using those.
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Old 03-30-2012, 03:50 PM   #3
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Just keep in mind that your sensor might not be the problem. It could be reading perfectly and your pump is just weak or the engine is worn and not providing good pressure.
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Old 03-30-2012, 03:59 PM   #4
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None of that would affect a simple on off sender. It either works it it doesn't. I'd be more incline to suspect weird electrical issues in the gauge or cluster.
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Old 03-30-2012, 05:33 PM   #5
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Quote:
Originally Posted by joshtowal View Post
Just keep in mind that your sensor might not be the problem. It could be reading perfectly and your pump is just weak or the engine is worn and not providing good pressure.
I totally agree. Take my truck engine for instance. If I was at a stop light and the engine was hot, the gauge would go down to zero pressure. As soon as I take off, the gauge would move back to the normal range. My engine ran well, but I knew it was worn out mainly because the previous owner never changed the oil and it was caked with sludge.

The fun of it, is I bought it specifically to rebuild the engine and was able to get it running well prior (minus the suspect oil pressure) to tearing it down.

I hear people say "dummy" gauge and I understand that, but I still think that it has to see a certain amount of pressure to function.
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Old 03-30-2012, 05:49 PM   #6
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That is correct,I believe the number is 7 psi but not sure. The op didn't ask about the gauge going to zero though, he asked about varying pressure indications. That's not a pressure issue on a binary sender.
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Old 03-30-2012, 10:46 PM   #7
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Sorry to argue guys, no special socket needed. Either a 27mm or a 24mm socket. It's dark and I don't feel like digging through the tool box. Like $5 at autozone. Buy your sending unit and go fit it to a 24 or 27mm socket. I'm almost 100% sure it was a 24mm. Both my 4.9 and 5.0 have had the sending units replaced in the last month and the metric socket did the trick without breaking a sweat.

EDIT!
Since I'm such a nice guy, I went and checked..........27mm 6 point socket. The alleged special socket was like $35. Screw that crap! I pissed Autozone off when I went and fitted the sending unit to one of their $5 sockets.
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Old 03-31-2012, 12:32 AM   #8
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Quote:
Originally Posted by unit505 View Post
The alleged special socket was like $35. Screw that crap! I pissed Autozone off when I went and fitted the sending unit to one of their $5 sockets.
Oh, I love it when solve your own problems right before their eyes.
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Old 03-31-2012, 12:32 AM
 
 
 
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