Low Oil Pressure ,Next Step

[strutaeng]

"It's probably your bearing clearances then." I agree and yes I still have the AFM stuff

I ask because I thought the AFM required higher oil pressure to work properly? I'm only familiar with the Gen III, not much on the Gen IV+.

I ran the 4.3 in my 99 Silverado for 10,000 miles with low oil pressure before I retired the engine. It had about 5 psi at summer hot idle checked with a mechanical guage when I started getting low oil pressure. My dash guage was below zero and the check gauges light came on at stoplights. I switched to 50 grade oil and pressure improved to around 8 psi and I kept running because I didn't have the money for another vehicle or engine then. I never got any knocking and engine still ran fine when I pulled it.

I did teardown the engine because I was curious. Rod, main and camshaft bearings had heavy wear. Measured 4-5 thousands clearance on main and rods. The pump was actually the one with minimal wear.

So except for the AFM lifter actuation (or however they work?), the engine may still run good with that oil pressure for a while if you don't have any knocking.

Next step: What are your capabilities mechanically, knowledge is and budget? Tools, time and space? That will dictate if you rebuild it yourself, have someone rebuild it, junkyard swap, crate engine, etc.

 

[Hoeston]

Hows she running now?

 

[Hoeston]

I recently changed my oil pressure sensor and the filter.
The check engine light had come on and oil pressure gauge stuck at max 80. 3 codes for the sensor failure.
Prior to changing the sensor/filter the gauge would idle around 30-35 when warm, closer to 40 when cold.
Now, after changing them, the gauge looks like 23-27 when warm, 36-40 cold.

Been wondering if this is the start of losing pressure

 

[Dustin Jackson]

@Hoeston Those sensors aren't calibrated for scientific accuracy so there will be variations between what the sensor reads, especially if going with non-factory oil pressure sensor

 

[j91z28d1]

I'd have to look it up again but the factory manual calls out low oil pressure something like 7psi hot idle. if you're at 20psi up to temp and idling at 600rpm you're doing better than most.

edit* plus all the dash gauges are kinda general. you really need a scanner to read the oil pressure as closely as you're trying to.

the water temp on the gauge center can be as much as 20deg different too and still show middle dash.

 

[2014PPV]

Hows she running now?

It's still going but the oil pressure is low—20 on startup and 12 after warmup ( 10-30w with Lucus.) Im not sure what route to go at this point. I have a low milage 4.7 from a 2005 but Im not sure how difficult, or costly the swap would be. It would be over my head so I would have to farm it out.

Hows she running now?

 

[Trey Hardy]

It's still going but the oil pressure is low—20 on startup and 12 after warmup ( 10-30w with Lucus.) Im not sure what route to go at this point. I have a low milage 4.7 from a 2005 but Im not sure how difficult, or costly the swap would be. It would be over my head so I would have to farm it out.

Do you hear any lifter tapping? If not it’s probably just a faulty sensor a possible solution for a more accurate reading is to add a mechanical oil pressure gage separate form the one on the gauge cluster for a more accurate reading possibly? Idk just throwing it out there I went through 3 sensors on my Tahoe and finally got sick of changing screens and or sensors when the last one went out I said f it and if I don’t hear no tapping I’m gunna send that biotch

 

[West 1]

Is the engine quiet as it runs? If it runs quiet, keep good oil in it and enjoy it till it wears out. I would consider using regular oil, not synthetic, I know all the synthetic advantages but one they do not talk about is synthetic will flow more or leak more as the engine runs. It is thinner when hot and will pass through holes that regular oil will not. So it is very good but not for all things. Petroleum based might raise your pressure up a tad. I would also switch to a 10-40 to help plug your internal leaks. If it starts and runs quietly keep running it, you might get another 75,000 miles before something fails.

 

[Charlie207]

Worn cam bearings, and leaking AFM/VLOM o-ring seals will lower pressure.