Buying a used AFM 5.3, any tips?

Ben Girard · July 27, 2015

Hi,

I'm in the market for a used silverado/sierra crew cab.

My budget of max 20K puts me in 2010-2013 territory, so possibly still with powertrain warranty.

Not going to argue about AFM here, I'm planning on getting a custom tune and getting it disabled right away.

With that said the trucks I'm finding have 100-130K miles. I plan on keeping it until it dies and hope to make it 250-300K

So what would you look when you're shopping so I don't end up with AFM related issues ?

Also what preventive maintenance would you do to start from a good known history?

Thank you.

Ben

newdude · July 27, 2015

Go as new as you can. 2012-2013 seem to be near trouble free as far as oil consumption issues, etc. 2010-2013 gets you the 6 speed 6L80 transmission as well vs. the old 4L60.

KMGZ400 · July 27, 2015

My dad has a 2013 5.3 with about 35 and it doesn't burn a drop! Just like any other problem, it gets blown out of proportion on the forum.

Ben Girard · July 27, 2015

In my price range it'd be a 2010-11. I don't want pre 09 because of the 4 speed.

@KMG400 Thanks, that's true too ... I can work on just about everything on a vehicle but really would hate rebuilding an engine in a truck I just dropped 20K on !

I am also looking at used LBZ or LMM. I'll post pics of whatever I get when I get it in a couple weeks.

2017SierraSLT · July 28, 2015

A friend has a 2010 5.3 with 110k AFM active. NO oil consumption or other drive line maladies.

Ben Girard · July 29, 2015

Glad to hear there are some good ones out there ! Thanks !

Ben Girard · July 31, 2015

I found trucks in my price range with 75-90K on the clock for 2011 models so still under warranty.

Now let's assume the truck burns oil. I get a tune, disable it. Are all my problems gone ? or do I need to go in for warranty work for this :

Bulletin #10-06-01-008I

And then get it tuned off and start with a good base?

2017SierraSLT · August 1, 2015

I found trucks in my price range with 75-90K on the clock for 2011 models so still under warranty.

Now let's assume the truck burns oil. I get a tune, disable it. Are all my problems gone ? or do I need to go in for warranty work for this :

Bulletin #10-06-01-008I

And then get it tuned off and start with a good base?

If they are currently burning oil, the rings are too carboned up to effectively clean them without taking the engine apart. If the engine is ok, then disabling AFM will prevent the rings from getting stuck.

Ben Girard · August 1, 2015

Sounds good !

The truck would still be under warranty and the problem would be taken care of if needed.

One more question.I've been researching for two days about PCV mod as to keep oil out of the intake. Why do people don't just reroute out it to somewhere under the frame instead of expensive catch/filter cans?

Is crank pressure that much of an issue.

I've always owned diesels and rerouted them in the open ...

2017SierraSLT · August 1, 2015

Sounds good !

The truck would still be under warranty and the problem would be taken care of if needed.

One more question.I've been researching for two days about PCV mod as to keep oil out of the intake. Why do people don't just reroute out it to somewhere under the frame instead of expensive catch/filter cans?

Is crank pressure that much of an issue.

I've always owned diesels and rerouted them in the open ...

Cars/light trucks prior to 1963 used road draft tubes, which all crankcase emissions went onto the ground and into the atmosphere. Roads were more oily and harmful HC emissions went into the air. PCV routed those liquids/vapors into the intake to be burned. This eventually leads to excessive carbon deposits. The catch can eliminates the oily liquids from being ingested into the engine preventing those harmful carbon deposits over time. It would violate the law if the PCV was disabled and the fumes went into the atmosphere.

Ben Girard · August 1, 2015

Thanks for your reply and I do understand that. So it's solely emissions related?

No crankcase pressure story behind it?

I do see some catch/filter cans in a closed loop going for 2-300 dollars which is crazy for what it actually is.

2017SierraSLT · August 2, 2015

Yes, PCV was emissions related.

The catch cans are pricey. I bought an Elite Engineering can, and it was $169 shipped. I have picked up 14 oz. of oily, watery liquid from it.

Ben Girard · August 6, 2015

Well I just put a deposit on a 2008 SLT LMM sierra, so I'll stay in my beloved world of diesel

I should be picking it up in a a week or two.

I'll post pics once I have it !

TonyMazz · August 9, 2015

Hello - I just bought a 2012 5.3 Silverado crew cab with 32k on the clock....dealer informed me that 5.3's after 2011 or newer have the corrected valve cover and oil pan splash deflector installed..... so far mine has not burned any oil after 2k of my own miles.....I am burning M1 5w-30....idles smooth runs good....I'd say go after the newer the better.....you should be fine.

GhostWriter · October 13, 2015

Hello, Everyone

Wanted to share something that might be interesting to some of you.

I bought a used Z-71 Avalanche with 65K on the odometer in 2012. At around 90K, it started to use a little oil - around 1/2 quart every 2000 miles.

The vehicle was still under warranty, so I wasn't ready to tune-out AFM. Instead, I began reading everything I could find about AFM & oil consumption.

What I found remarkable was the amount of anecdotal evidence pointing to the original valve cover PCV baffle design as the main culprit. Since there is a significant cost to turning off AFM, I decided to remove my L/H valve cover for a look see @ 95K.

The baffle was pretty caked-up, so I ordered a cover with the new design for around $110. As many of you already know, the old baffle had a drain hole which was positioned directly above one of the drain holes in the head. In some engines, an excessive amount of oil was sucked into the intake. The new design moves the baffle drain hole away from the head drain hole.

Closing in on 2000 miles since the swap, and it doesn't appear to have used any oil. Since I had done my homework, this didn't surprise me.

What surprised me was how my mileage increased from 14.5 miles to the gallon, to just over 16 MPG. Obviously, my 5.3 wasn't breathing very well.

Knowing what I know now, my first order of business for a pre '11 GMT900 5.3 would be to replace the valve cover. If the rings haven't already started to stick, there may be hope for the engines that are pre-disposed to oil consumption.

Thanks for listening, & have a nice day.