Thoughts on post AFM delete oil pressure?

[Dustin Jackson]

Since doing my AFM delete and replacing the factory oil pump with a standard oil pump my oil pressure is a little lower than it used to be, is this a concern?

Here is a cold start idle oil pressure


Here is after three hours of driving up and down mountains and then idling

 

[Foggy]

That's certainly within the "normal" range... Drive On !!!

 

[Meccanoble]

This is exactly what my car does

 

[B-train]

The trucks with AFM have a higher volume oil pump to actuate the lifters for the system. If you look at a non-Afm motor like a 2007-09 6.2L, any 4.8L, or the HD truck 6.0L you will find a different block off plate in the valley. It is completely flat and has a bunch of o-rings that seal off the oil passages that aren't used for those motors.

So, going to a normal pump will give you what you are seeing. For reference, my 2008 Denali looks the same as what you posted and it has 172k, is non-afm, and has the original pump still. Rule of thumb used to be 10 psi for every 1000 rpm, so your current pressure is very adequate.

I have personally experienced low oil pressure on a 6.2L with over 200k. Ended up being a combo of the o-rings under the valley plate being compressed and allowing oil to sneak past which lowered the pressure and a cracked o-ring on the oil pump pickup tube. I would get lifter clatter on any hot restart with the oil level full. Yikes! All ended up good after the fix. These motors are tough, so you are all good my friend!

 

[Dustin Jackson]

The trucks with AFM have a higher volume oil pump to actuate the lifters for the system. If you look at a non-Afm motor like a 2007-09 6.2L, any 4.8L, or the HD truck 6.0L you will find a different block off plate in the valley. It is completely flat and has a bunch of o-rings that seal off the oil passages that aren't used for those motors.

So, going to a normal pump will give you what you are seeing. For reference, my 2008 Denali looks the same as what you posted and it has 172k, is non-afm, and has the original pump still. Rule of thumb used to be 10 psi for every 1000 rpm, so your current pressure is very adequate.

I have personally experienced low oil pressure on a 6.2L with over 200k. Ended up being a combo of the o-rings under the valley plate being compressed and allowing oil to sneak past which lowered the pressure and a cracked o-ring on the oil pump pickup tube. I would get lifter clatter on any hot restart with the oil level full. Yikes! All ended up good after the fix. These motors are tough, so you are all good my friend!

@B-train How does that oil pressure spec work for higher RPMs? For example when I'm at 5000RPM I only have 40 PSI, or the gauge only shows 40 at least. Is that unhealthy at 5,000 rpm?

 

[B-train]

That's a good question. The only way to know is with a good calibrated manual guage and see where it goes based on rpm. Again, older reference that I worked with, but I never got into high rpm running as a regular thing.

My guess is that you are at more than 40 psi at 5k. Most idiot guages are just a buffered electrical signal given to a stepper motor.

Funny story about high rpm: I had to rent a vehicle for work to pull a trailer. The truck (tahoe) didn't like pulling in 6th gear, so it stayed between 4th and 5th defending on the freeway speed. It ran at 4k for over 1000 miles straight. Never had an oil pressure or delivery issue.

As long as you aren't hanging out all day at 5k I think you'll be fine. Plus, everything else takes more abuse at that rpm for shifting, accessories, etc. Probably best to just use the normal rpm range and save 5k for special occasions.