Oil Pressure at 80 then drops to 0

[StickerShockPDX]

2003 Yukon Denali XL 6.0

My oil pressure has been running at 80 since I got the truck about a month ago. Just recently it started to drop low and even to zero, usually after warmed up and above 50mph. I changed the oil right after this started thinking it might be a clogged filter. This didn't help and it seems to be getting worse.

I need to take a trip next week and need to solve this asap.

I was thinking maybe a clogged oil pump intake or a failing oil pump? I've done a lot of "easy" work on vehicles over time and I'm wondering if this is relatively easy to handle? Or if it might be something more serious?

It usually drops if I am in higher gears and go above 2700 rpm.

 

[Chiggy]

Go to the parts store and get a new oil pressure sending unit. It's behind and below the intake manifold by the firewall. It's easy to change with a sensor socket and a mirror. I think the sensor is about $20

 

[StickerShockPDX]

You think that might be all it is? It doesn't seem to make any odd noises and it is at the right oil level.

 

[SteveCZ28]

oil pressure switch is fairly cheap place to start. its possible yours is starting to crack and fail, as they are made of plastic

 

[StickerShockPDX]

Thank you both, it does have 229k so I will start with that. Am I right reading somewhere that it is a 27mm? Anyone think maybe Autozone has that size to lend?

 

[SteveCZ28]

im not sure on the 5.3's. i know there is a special tool required to remove the o.p.s on the ls 5.7's

 

[Chiggy]

You don't exactly need a special tool but once you see the sensor and the correct socket for it you'll understand how much easier it will be if you have one.

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[Goodinblack]

Put a gauge on it instead of throwing parts at it imo

 

[StickerShockPDX]

I've read about putting a gauge on it... where do I put it and where do I get a gauge to use?

Also, occasionally I smell a bit of burning oil. It smells clean, like if you spilled on the engine when adding oil. I see a little oil grime build up at the pan near the plug and filter. I made sure to put a new washer on the plug when I did the oil last week and I still get that little whiff once in a while. This makes me think SteveCZ28 may be right on the crack and a little oil gets out and burns? Before I changed to oil it was fairly clean but I wanted to do it myself so I knew when it was done.

 

[Chiggy]

It's a common issue for the sending unit to go out. I've changed a few. If you do spend the $20 to change it then you know it isn't the sending unit and it's either the stepper motor in the gauge or something more serious. Just don't buy the house brand at o'rileys. I got a bad one new out of the box last time.
If your oil pressure is dropping to zero on the highway or at any time really you'd already be hearing a knock or the beep of the tow truck backing up. It shouldn't be at 80psi either unless your foot is to floor at 3k+ rpm

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