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Old 10-17-2017, 01:00 PM   #1
LBJ
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2004 Vortec 5.3 Oil Pressure Sending Unit?

I suspect my oil pressure sending unit may be going crazy, so want to replace it. First, since I don't have any service manuals, I need to know where the unit is.

It's a 5.3 LS style (Vortec) gas engine in a 2004 Silverado 1500 4WD.

Anyone got a photo? Or link to a shop manual?

Thanks, LBJ
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Old 10-17-2017, 01:46 PM   #2
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

right at the back of the intake manifold where its located on a smallblock...this is a ls3 but they're all in the same location that I've seen on LS...
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Old 10-17-2017, 05:34 PM   #3
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

Good photo. Kinda have to crawl over the engine to get to it though. Ha. Many thanks. LBJ

Will a regular deep socket fit over that? Hate to buy a special socket for that one thing.
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Old 10-17-2017, 07:38 PM   #4
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

I used a socket to get mine out but I don't remember the size
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Old 10-17-2017, 09:03 PM   #5
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

1-1/16" socket, Your lucking a standard socket will fit '03/'04/'05/'06 truck sending units as earlier & newer require specialty sockets! Now it may require a thin wall chrome as a impact socket may not clear the valley cover (Gen 3 engines are different than the Gen 4 shown in the pic).
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Old 10-26-2017, 02:29 PM   #6
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

I got the new part and socket and looked at the engine. Wow, I couldn't get my right hand in past the harness and some other tube in the way. In fact, I can barely see the top of the harness to the oil pressure sensor. If I could get past the things in the way, I might be able to feel my way down to remove the wiring and change it out. right now, guess I'll have to stay with the one that's in the block.
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Old 10-27-2017, 03:35 PM   #7
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

make sure the area is free of oil & debris -that might fall in sending unit hole ! ive seen instances where something has fallen in hole !!
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Old 10-27-2017, 05:40 PM   #8
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

I have looked at the unit every which way, and cannot get to it without removing some of the cables, harnesses, etc, that are in the way. I also looked at the PVC valve and tried to remove it - it acts like it was installed with a hydraulic ram! I even tried using pliers to pull it out of the seat. Nothing doing.
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Old 10-28-2017, 12:00 AM   #9
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

LBJ, I believe that once you remove the sender look down inside the hole and i think there is a small screen that gets varnished/plugged up, but gm sell a new one. This screen issue can make a perfectly working sender indicate wrong because oil pressure gets blocked/plugged.
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Old 10-28-2017, 08:36 AM   #10
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

Unfortunately, I cannot get to the pressure sensor to remove it (much less see it) without some fairly complicated disassembly of fuel lines and wiring harnesses etc. Guess I'll have to live with the sensor that's in there now. Just not a major problem at this point. Thanks for the tip though.
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Old 10-28-2017, 10:26 AM   #11
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

Not sure if I understood it correctly but I seem to recall reading where someone converted the oil cooler block off plate to install a sending unit.
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Old 10-28-2017, 12:12 PM   #12
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

Not sure where the oil cooling block-off is either. I have purposely left this engine alone for 13 years other than change the oil and filters. Been running fine till now so I hated to mess with perfection. Ha

A couple of pics. You can see the fuel line and several other lines in the way. Pretty tough to get behind the engine. That big hump at the end of the intake manifold doesn't help any. On the passenger side, I tried a reach around and no way there either. I suppose I could start taking the fuel line apart and getting it out of the way, but don't want to open a can of worms on the fuel injection system.
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Old 10-28-2017, 03:46 PM   #13
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

It's more feeling than seeing. You can get to it without unhooking any fuel lines or harnesses. The only thing you need to unplug is the electrical connector at the sending unit. Then slip the socket on. Then an extension. Then a ratchet. You'll mostly be working from the drivers side.
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Old 10-28-2017, 03:50 PM   #14
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

There is not a pcv valve on your engine either. There is a fixed orifice in the valve cover. Take the pcv valve back and return it.
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Old 10-28-2017, 05:28 PM   #15
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

Cannot even get my hand down there to "feel" my way thru. Just no way - too much crap in the way. Haven't bought a PCV valve yet, just checking to see if it needed replacing. Ha
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Old 10-28-2017, 05:29 PM   #16
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

i had an 05 5.3 k1500. i took plastic cover off top of engine and laid a sleeping bag on top of engine. i crawled on top of engine with 3/8 ratchet 5 inch extension and socket.i looked down and saw oil sending unit and 2 minutes later i had it changed. old money.
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Old 10-28-2017, 05:50 PM   #17
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

mine had one on it ...looks like this...its right above the oil filter. ..
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Old 10-28-2017, 06:31 PM   #18
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

Try to go beside the drivers side of the intake manifold. I have large hands and can feel them.
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Old 10-28-2017, 08:23 PM   #19
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

I've been right on top of the driver's side of the engine. Just cannot get my hand thru the mess of lines, much less hold a ratchet. Everything's pretty solid on all those cables and such. If I knew what would happen if I disconnected the fuel line, that would be cool. But, I don't want to get a fuel feed problem started. You know, introducing air into the line. I know very little about fuel injection systems, owned all carbed cast iron engines up till now except for 2 C5 Corvettes (99 and 01). Never had to mess with them at all.
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Old 10-28-2017, 08:28 PM   #20
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

pulling the fuel line will cause no issues..just use the tool
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Old 10-28-2017, 08:49 PM   #21
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

And depressurize the fuel system. Remove the fuel cap and the fuel pump relay. Attempt to start the truck. Crank it a few more times. Use a rag to catch fuel when you unhook the line. Like previously stated, use the fuel line disconnect tool.
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Old 10-29-2017, 07:13 PM   #22
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

Is the fuel line disconnect tool something that is widely available? Like Auto Zone or O'Reillys? I'll do a search.
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Old 10-29-2017, 07:25 PM   #23
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

yep...our local oreillys has them in their loanatool section...comes in a set with different sizes

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Old 10-29-2017, 07:34 PM   #24
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

OK, good. I just watched a You Tube video on how to do the job. Just never worked on these LS/Vortec engines yet. Ha. I may be able to get to the sensor with that fuel line pulled out of the way. Glad it's not that tough to do. Thanks all!
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Old 10-30-2017, 06:51 PM   #25
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Re: 2004 Vortec 5.3 Oil Pressure Sending Unit?

Good news, I changed out the oil pressure sensor. Bad news is it didn't change anything! ha. Still hits 70PSI when the engine is cold while accelerating and stays between 40-50 PSI in normal driving. Oh well, at least I got the job done. The fuel line disconnect tool worked fine. Was able to get the old sensor out by feel mostly, and get it all put back together successfully. Thanks to all the help here, I appreciate it. I did order a code reader from Rock Auto to see if any more codes have been set. It will be here in a few days.
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