No oil pressure '04 Yukon

[Mortimer452]

Vehicle has only 127k miles. Driving home the other night glanced down at gauges and oil pressure reads zero. No other warnings lights, but gauge is at zero.

Fortunately I was like 1/4 mile from my house so I zipped into the driveway and shut it off immediately, not sure how long it had been at zero but didn't want to cause any further damage.

I am guessing maybe it's the sending unit, but want to know for sure before I go driving around any more. Oil level is fine, underbelly is dry as a bone with no evidence of leaking anywhere. Is there any way to tell for sure the sending unit is bad so I know it's safe to drive?

 

[mattbta]

The effort to swap the sending unit vs putting a mechanical gauge on the same port to check pressure is the same. Did it ever peg to the right fully? Usually that is indicative of the sending unit. Otherwise, it could be a stepper motor in the cluster.

 

[Mortimer452]

The effort to swap the sending unit vs putting a mechanical gauge on the same port to check pressure is the same. Did it ever peg to the right fully? Usually that is indicative of the sending unit. Otherwise, it could be a stepper motor in the cluster.

Thanks for the reply. Yeah it pegs to the right with all other gauges when I turn the key on, just resets to zero after start. My repair manual makes that sending unit replacement sound like an absolute PITA - removing the intake? Is it possible to replace without pulling the intake?

 

[mattbta]

Thanks for the reply. Yeah it pegs to the right with all other gauges when I turn the key on, just resets to zero after start. My repair manual makes that sending unit replacement sound like an absolute PITA - removing the intake? Is it possible to replace without pulling the intake?

If you've got scrawny arms like me and a collection of extensions/wobblers, you can do it without intake removal. Swear I've seen a thread or two on here with pics.

Did it make any _bad_ noises prior to turning it off in your driveway?

 

[JPVortex]

Yeah I'd hook a manual gauge before you freak out anymore. Doing it with the intake on is very simple. Was able to do it with my fat fingers. The hardest part by far is getting the hose for the manual gauge on which required lots of choice words. Get a 1 1/16in oil pressure sending unit socket(a regular 1 1/16 would not fit over the unit for me) then a 3/8 wobble socket, followed by a 6 inch extension then a ratchet, then you should be able to get it off.

Most manual gauges wont come with the right size threads for where the sender goes. So you'll need to order an adapter.

 

[Mortimer452]

If you've got scrawny arms like me and a collection of extensions/wobblers, you can do it without intake removal. Swear I've seen a thread or two on here with pics.

Did it make any _bad_ noises prior to turning it off in your driveway?

No I think I'm good, I was definitely paying close attention, ran just like normal. Made that mistake once in my old '85 truck, thought I could get home and it gave the screech of death in about 3 minutes

 

[Fless]

Yeah I'd hook a manual gauge before you freak out anymore.

Most manual gauges wont come with the right size threads for where the sender goes. So you'll need to order an adapter.

@Mortimer452 what does the gauge do with the key on but the engine off? (KOEO)

For a pressure gauge: M16-1.5 male to 1/8" NPT female:

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