AFM

[Chert_Detective]

I don't buy the whole, "GM fixed this around 2010" spiel. In my opinion, it is a flawed design and I will never own an AFM truck. The two trucks in my sig do not have AFM. If I have to, I'll get a Ram or Super Duty before I get AFM.

That being said, what I've seen and read is that it will act up most likely from 75k-100k miles, with collapsed lifter(s). If the engine makes it to 100k-125k with no issues, you got a good one.

Once, when I was looking to buy, I saw a used 08 Avalanche for sale with 96k miles that had just had the engine replaced. That, I would have bought. And then immediately disabled the AFM.

If I was to end up with an AFM vehicle I would delete it. It would be a good excuse for a nice cam.

Purposely bought my '08 for this exact reason. Bought it with 147k miles in 2017, no AFM, good service history, etc. About 185k-ish I got "the tap". Showed up, never went away never got worse. Around 190 I decided I wanted to keep it and dump the money I did into it and have a fun bada$$ daily vs spending the money on something new, boring, and depreciating. So I started gathering parts.

Upon tear down, only one lifter was bad but was on its way to being completely toast and wiping the cam. And this was the #7 piston, couldn't tell you when it happened, engine never gave me any signs.

 

[Rocket Man]

Purposely bought my '08 for this exact reason. Bought it with 147k miles in 2017, no AFM, good service history, etc. About 185k-ish I got "the tap". Showed up, never went away never got worse. Around 190 I decided I wanted to keep it and dump the money I did into it and have a fun bada$$ daily vs spending the money on something new, boring, and depreciating. So I started gathering parts.

Upon tear down, only one lifter was bad but was on its way to being completely toast and wiping the cam. And this was the #7 piston, couldn't tell you when it happened, engine never gave me any signs.

View attachment 259915

That’s crazy. Wonder where that piece went?

 

[swathdiver]

That’s crazy. Wonder where that piece went?

Right into a catalytic converter!

 

[Chert_Detective]

That’s crazy. Wonder where that piece went?

Right into a catalytic converter!

I can only assume, but we never found it. Combustion chamber, valves, exhaust port.. no sign of damage. No CEL, no sudden loss of mpg or oil consumption, nothing. Didn't find anything in the cat. It just... vanished. It broke and just yeeted itself on out haha. Thankfully I started the build before the lifter really went and cost me an entire engine. Pan was already off so we just pushed that piston and rod out and slapped a piston on it from a previous customers engine.

 

[Rocket Man]

Right into a catalytic converter!

Duh. But I mean it had to go out an exhaust valve so where’s the damage? Weird that he found no exit evidence.

 

[91RS]

Most of the vehicles I’ve seen with cracked ring lands still run fine. They usually come in complaining of massive oil leaks from the blow by.

 

[Just Fishing]

Oh baby.

Thinking that was caused from burning oil via the pcv and then a sticking ring or something?

 

[Chert_Detective]

Oh baby.

Thinking that was caused from burning oil via the pcv and then a sticking ring or something?

It's possible. The manifold didn't have any liquid oil in it when it was pulled though and it never smoked during a pull. Who knows, running great now on 7 used and 1 double used lol.

 

[Handyone]

What can one expect to pay for a "AFM" removal?