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2007 Yukon XL Denali low oil pressure after warming up

chealey1

By chealey1
in Ask A GM Technician

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chealey1 New Member

chealey1

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Just picked up a used 07' Yukon XL Denali 6.2 litre. There's no AFM in it. Upon starting and first 10 minutes of driving oil pressure is awesome and between 45-50 but then drops down to 6-9 while idling.It does go back up to 40+ upon driving though. I've read a bunch of forums with no definitive or exact same problem and answers. Anyone have any suggestions? Truck has 160K and all else seems fine except volt gauge also has a tendency to drop down to 13 when warmed up and then goes back up to 14. This is my 5th Yukon/Suburban and I thought I'd seen almost everything...

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

She's probably a little tired - getting close to the end of it's life. If it's not making a racket at idle, I wouldn't worry too much about it. I've run vehicles back in the day 100k+ miles with pressure like that, read off a more-accurate, aftermarket direct pressure gauge (non-electric).

 

Start running 10w30 now, and maybe 20w-50 in the summer - that'll help with the excessive clearances to slow down the bleed-off.  

 

Now since you mentioned your volt meter, this might just be a simple case of a dirty throttle body keeping your idle speed too low. That will cause everything you described - low oil pressure and voltage. Throw a scan tool on there, and compare your desired to actual engine RPM - they should be very close (within 50-100 rpm).

chealey1 New Member

chealey1

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50 minutes ago, Jsdirt said:

She's probably a little tired - getting close to the end of it's life. If it's not making a racket at idle, I wouldn't worry too much about it. I've run vehicles back in the day 100k+ miles with pressure like that, read off a more-accurate, aftermarket direct pressure gauge (non-electric).

 

Start running 10w30 now, and maybe 20w-50 in the summer - that'll help with the excessive clearances to slow down the bleed-off.  

 

Now since you mentioned your volt meter, this might just be a simple case of a dirty throttle body keeping your idle speed too low. That will cause everything you described - low oil pressure and voltage. Throw a scan tool on there, and compare your desired to actual engine RPM - they should be very close (within 50-100 rpm).

No racket at idle, quiet and smooth. I still own my 03 Suburban which I bought brand new and I have 306K on her, orig motor and trans, still runs great too... Now she may be heading towards the end but this Denali with 6.2 litre is barely broken in, it was a grocery getter and maintained meticulously. Thanks for your help, I'll clean throttle body up but I suspect a grounding issue or electrical problem too. IDK.... Thanks Again

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

Not a problem. Definitely could be an electrical issue regarding the pressure gauge as well, or a bad, or dirty sending unit, or even a bad stepper motor in the cluster. Usually engine noise will tell the tale, but if in doubt, remove the sender and install a mechanical gauge just to check to be sure. 

txab Senior Enthusiast

txab

Posted
Posted
34 minutes ago, Jsdirt said:

Not a problem. Definitely could be an electrical issue regarding the pressure gauge as well, or a bad, or dirty sending unit, or even a bad stepper motor in the cluster. Usually engine noise will tell the tale, but if in doubt, remove the sender and install a mechanical gauge just to check to be sure. 

 

Doug_Scott Senior Enthusiast

Doug_Scott

Posted
Posted

+2 or +3 never could understand it.  I have always used the formula of 10psi per 1,000 rpm for oil pressure. 

 

I recall having common gauge issues with a certain make/model that I can't recall off the top of my head, but it was giving similar issues.  It was the ground wire for the cluster.  Too low of gauge wire for the ground wire.  It was creating 1v drop.  It impacted fuel gauge in addition to the oil pressure and coolant temp. 

Don't know enough about the wiring in these vehicles to know if it's something to look at. 

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