i have a 2007 yukon denali 6.2 liter , i keep getting low oil pressure , i replaced oil pressure sensor , oil pick up tube and o ring, new oil pump new oil and filter truck runs good 40 pounds of oil pressure on start up when cold. at operating temp oil pressure starts to drop i put on mechanical gage at the oil pressure sensor oil pressure is about 9psi HELP!!!!

 

Time for some bearings and rebuild

 

motor makes no noise cold or hot only 130k

 

motor makes no noise cold or hot only has 130k

 

That's pretty low miles for these engines, but unfortunately, I'll also say bearings are worn. How long have you owned the truck? Do you know the maintenance history on it?

I had a 4.3 Vortec on my 99 Silverado that pretty much did the same. I had about 7 psi at hot idle when checking with a mechanical gauge. By then, the check gauges message was popping up in the message center. I was at 250k, so didn't make sense to mess with it anymore. I changed to the heaviest weight oil available (40 weight IIRC and pressure increased to 10 psi at idle), and ran it for another 10k miles. Engine never made noises.

I eventually pulled the engine and tore it down. Main and rod bearing clearances were around 4.5 to 5 thousands. About double of what a healthy motor should be.

 

i noticed i have a very small oil leak coming from the top in the back of the motor it looks like the person before me has had the center AFM plate off under the intake.
looks like thats where the oil leak is coming from. i can see a terrible RTV job. i just bought the truck could this possibly cause low oil pressure if that gasket is ruined or leaking?

 

Not too likely to be the source of the low pressure, unless it's leaking really bad. I could be wrong on that. It's the valley cover that's leaking? Maybe the little AFM towers are leaking internally if they did the AFM delete? I'm not familiar with the AFM engines.
Did the seller tell you about the low oil pressure?

 

So if it were me i would pull the Valley cover and make sure all the o rings are in place.. That is a bad place for a oil leak internally.

If you cant find the o rings just buy a $9 A37 bearing. Cut the cage and use the roller bearings to press into the towers. ONLY DO this if you already have DOD Disabled in the tune.

9psi is ok for idle tho, just not great cause the oil flow is going somewhere. Every low oil pressure 6.2 ive been in had worn bearings and a simple rebuild with a new oil pump brought it back to life.
Alum 6.2s are terrible about loosing oil pressure for some reason. I think its 5psi minimum pressure at hot idle so your close.

Ive gone in there and put 10355 oil pumps with a shimmed spring to get oil pressure back at idle to prolong the inevitable. Some were able to drive them a couple months with 20w50 oil till we could get them another engine and freshen it up to swap in.