L92 low hot oil pressure at idle HELP!!!!

[Jakob0327]

2007 gmc yukon denali xl, cold oil pressure is up to 50psi when starting, slowly declines until once engine is up to operating temperature, it's just above the red hash mark or a small gap above it. Just did a oil change, and I drive this thing 150 miles a day so I can't afford to have it go down. Does anyone know what it could be? I just bought a new valley pan because it looks like it's seeping a little bit and I've heard if the o rings flatten out on the oil galleys it will bleed pressure off there. When driving down the interstate at 1700-1800rpm it will be about 30psi. Not a new issue with this i just drive alot more now so it causes me alot more worries. I was told by the previous owner it's normal bc it's not below 6psi which I didn't feel right with to begin with, as my 6.0l makes 35psi hot idle with stock pump. Am I looking at the infamous pickup tube o-ring, oil pump? Or very worst case scenario with an engine? Any insight would be appreciated. I'm going to install the valley cover tomorrow in hopes it will help

 

[kbuskill]

2007 gmc yukon denali xl, cold oil pressure is up to 50psi when starting, slowly declines until once engine is up to operating temperature, it's just above the red hash mark or a small gap above it. Just did a oil change, and I drive this thing 150 miles a day so I can't afford to have it go down. Does anyone know what it could be? I just bought a new valley pan because it looks like it's seeping a little bit and I've heard if the o rings flatten out on the oil galleys it will bleed pressure off there. When driving down the interstate at 1700-1800rpm it will be about 30psi. Not a new issue with this i just drive alot more now so it causes me alot more worries. I was told by the previous owner it's normal bc it's not below 6psi which I didn't feel right with to begin with, as my 6.0l makes 35psi hot idle with stock pump. Am I looking at the infamous pickup tube o-ring, oil pump? Or very worst case scenario with an engine? Any insight would be appreciated. I'm going to install the valley cover tomorrow in hopes it will help

Hard to give a definitive answer as it could be several things. If the valley cover and new gaskets doesn't improve it my guess is it is probably the O-ring on the pickup tube.

The easiest way to diagnose this is to over fill the crank case by about 2 quarts and park the truck with the nose pointing down hill, like nosed into a ditch, and see if the low oil pressure improves. I wouldn't run the truck like this for an extended period of time but for testing purposes it won't hurt anything.

You didn't mention how many miles were on the engine, but with it being an '07, if it hasn't recently had the pick up tube O-ring replaced, then that is the most likely culprit.

 

[donjetman]

Sounds normal to me. I've had the same engine for 6+ yrs and 70k miles.

Based on age, changing the oil pump pickup tube o-ring is long overdue.

If you want higher oil presure install a high pressure spring in the oil pump
and/or
run higher viscosity oil like M1 5w-50, etc, etc.

 

[Jakob0327]

Sounds normal to me. I've had the same engine for 6+ yrs and 70k miles.

Based on age, changing the oil pump pickup tube o-ring is long overdue.

If you want higher oil presure install a high pressure spring in the oil pump
and/or
run higher viscosity oil like M1 5w-50, etc, etc.

So this isn't going to cause it to grenade?

 

[Joseph Garcia]

I believe that you should take @kbuskill 's advice and test for the pick up tube O'ring failure. My L92 goes down to about 20 psi at idle with the oil hot, and I have a new oil pump and pick up tube O'ring. Personally, I would not be comfortable with an idle oil pressure below 20 psi. On the positive side, it appears that your oil pressure is normal at higher rpm's than idle.

 

[rdezs]

I would do a crankcase overfill and point downhill as advised, just to confirm you probably are due for that o-ring.

But prior to that I would get and oil pressure sending unit relocation kit, readily available online, that put your sending unit in a more serviceable spot. (You can wire tie it up to the firewall) Once you do that, I would install a mechanical gauge in place of the OEM sending unit and verify your oil pressures. After that I would do the overfill test pointed downhill, if the mechanical gauge confirms with the gauge on your dash tells you.

You can also get an adapter to put on the end of the steel braided hose on the relocation kit, that has a place for your OEM sensor and a place to thread in a mechanical gauge. (Which you could just leave in place if you want, or thread in a plug when done) The advantage to having both at the end of the relocation kit is you can compare the two gauges in real time.

 

[the 18th letter]

Is is possible that the gauge is not accurate?

 

[rdezs]

Yes.

 

[Jakob0327]

Update after today, did the new valley pan gasket and I am afraid I might have to try the downhill test. I am curious what kind of EOP relocation kit your mentioning though! I did find a crushed O ring or 2 on the valley pan but when up to idling rpm I'm sitting with 18 19 now verified by the edge cts insight I have. I believe i have a faulty gauge as well due to my edge saying 18 19psi and my gauge sitting slightly above the red line. I think I might even try adding some 5w40 instead of they 5w30 in hopes it will make it a little higher.

 

[kbuskill]

Update after today, did the new valley pan gasket and I am afraid I might have to try the downhill test. I am curious what kind of EOP relocation kit your mentioning though! I did find a crushed O ring or 2 on the valley pan but when up to idling rpm I'm sitting with 18 19 now verified by the edge cts insight I have. I believe i have a faulty gauge as well due to my edge saying 18 19psi and my gauge sitting slightly above the red line. I think I might even try adding some 5w40 instead of they 5w30 in hopes it will make it a little higher.

I believe GM says 6 psi per 1000 rpm to float the crank. But I personally prefer more pressure.

I installed a high volume/high pressure pump in mine many years ago and I actually had to install a resistor inline with the oil pressure sensor to trick the computer into thinking I had less oil pressure because it kept setting a CEL for the oil pressure being too high/out of range.

 

[rdezs]

Keep in mind any device you plug in to read the oil pressure, is reading it off the same oil pressure sending unit your dash gauge is using. So if your dash is reading lower than your device plugged in, you probably need a new stepper motor in your instrument cluster. That's a pretty common issue in GM clusters. Rebuilt clusters with new stepper motors and LED lights are readily available and not too expensive. I have a local guy that does a mobile service and it takes him about half an hour to replace all the stepper motors for around $150.

Hopefully since you changed the valley cover, you replaced the oil pressure sending unit while you're in there?

LSX Oil Pressure Sensor Relocation Kit https://a.co/d/h30NSnG

But due to age and mileage, I would do the o-ring regardless. It's more of a maintenance item on the lS engines at this point.

 

[Jakob0327]

Keep in mind any device you plug in to read the oil pressure, is reading it off the same oil pressure sending unit your dash gauge is using. So if your dash is reading lower than your device plugged in, you probably need a new stepper motor in your instrument cluster. That's a pretty common issue in GM clusters. Rebuilt clusters with new stepper motors and LED lights are readily available and not too expensive. I have a local guy that does a mobile service and it takes him about half an hour to replace all the stepper motors for around $150.

Hopefully since you changed the valley cover, you replaced the oil pressure sending unit while you're in there?

LSX Oil Pressure Sensor Relocation Kit https://a.co/d/h30NSnG

But due to age and mileage, I would do the o-ring regardless. It's more of a maintenance item on the lS engines at this point.

I am definitely going to as well as plugging the AFM oil pressure bypass valve in the oil pan itself. I did replace the sensor as well.

 

[Charlie207]

How many miles on the engine?

 

[mickier]

I'd run some STP (thick type oil additive until you find the problem though

 

[Smulvey585]

I just changed to 15-50 Mobil 1
It’s warm weather now.
The startup psi=52
The warm running is + 30 psi

No more ticking in startup

I have a 6.2. 2014 98,000 miles with the AFM intact.

 

[Actifenpleinair]

2007 yukon Denali L92 with 277,000 miles, 5w30 synthetic, 6-7500 mile change interval, UPF63R filter, since 160,000 miles purchased w/ 6L80 rebuilt
i had lowish oil pressure at hot idle in gear, ~13psi. Internals and VVT all stock
Used my Banks Automind tuner to raise P and N idle to 700 R,D,M idle to 600, hot oil pressures of -19 psi, highway ~2000 rpm hot 30+psi. Seems to keep from low oil pressure and stalling. IDK, seems simple, what are your thoughts?
Lou

 

[Geotrash]

2007 yukon Denali L92 with 277,000 miles, 5w30 synthetic, 6-7500 mile change interval, UPF63R filter, since 160,000 miles purchased w/ 6L80 rebuilt
i had lowish oil pressure at hot idle in gear, ~13psi. Internals and VVT all stock
Used my Banks Automind tuner to raise P and N idle to 700 R,D,M idle to 600, hot oil pressures of -19 psi, highway ~2000 rpm hot 30+psi. Seems to keep from low oil pressure and stalling. IDK, seems simple, what are your thoughts?
Lou

It's a bandaid, but if it works...

The root cause is likely the oil pump pickup tube o-ring, but it's a bear to replace because you have to drop the pan. Could also be worn cam bearings, but my money is on the o-ring.

 

[rdezs]

Definitely a Band-Aid. I would also shorten your oil change intervals to no more than 4,500 miles.

I'd put my money on the pickup tube o-ring, a weak oil pressure relief valve in the oil pump.... It's probably collected it's share of crud over the miles.... And your first two cam bearings. Treated nicely, more frequent oil changes, it could last a week or it could go another hundred thousand miles

 

[j91z28d1]

2007 yukon Denali L92 with 277,000 miles, 5w30 synthetic, 6-7500 mile change interval, UPF63R filter, since 160,000 miles purchased w/ 6L80 rebuilt
i had lowish oil pressure at hot idle in gear, ~13psi. Internals and VVT all stock
Used my Banks Automind tuner to raise P and N idle to 700 R,D,M idle to 600, hot oil pressures of -19 psi, highway ~2000 rpm hot 30+psi. Seems to keep from low oil pressure and stalling. IDK, seems simple, what are your thoughts?
Lou

I like it.. it's at 277k, it owes you nothing.


you could test the o ring with the over fill with oil and face down hill and see if the pressure comes up.

 

[Campie]

Hard to give a definitive answer as it could be several things. If the valley cover and new gaskets doesn't improve it my guess is it is probably the O-ring on the pickup tube.

The easiest way to diagnose this is to over fill the crank case by about 2 quarts and park the truck with the nose pointing down hill, like nosed into a ditch, and see if the low oil pressure improves. I wouldn't run the truck like this for an extended period of time but for testing purposes it won't hurt anything.

You didn't mention how many miles were on the engine, but with it being an '07, if it hasn't recently had the pick up tube O-ring replaced, then that is the most likely culprit.

How difficult is it to replace that o-ring?