It's AFM week.

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Had 2 more trucks come in with AFM issues after I fixed the 2008 Silverado for a good customer on the cheap. A lot of things seem to come in Three's at repair shops.

1st one is another LMG 5.3L 2008 Silverado that was also missing on #4, It's getting a full AFM delete with a LQ4/LQ9 Camshaft, GM Performance "Bowtie" Lifters, 3-Bolt Cam Gear, LS2 Timing Chain, LS2 Timing Chain Damper, Melling HV-SP Oil Pump, L92 Valley Cover, ARP Exhaust manifold bolts, Along with plugging the AFM relief valve in the Oil Pan.

2nd one is a 2011 GMC Yukon Denali XL with a L9H 6.2L, Cylinder #7 Intake Lifter deactivates soon as the engine is started....But seems to be locked in the activated position when barring the engine by hand, In fact the Rocker actuates well 'til it get's oil pressure.
This is just another failure mode to add to the collection of AFM Lifter failure modes......
The Lifter has a internal oil leak between the "Lash" chamber that's fed oil at all times & the "Deactivation" chamber that's only suppose to get oil pressure when the cylinder is deactivated.
I tried to sell a full AFM delete using a L92 Camshaft, But the customer has cash flow issues, This one is getting the Lifters replaced on Bank 1 only with low mileage used ones I have laying around. Tried to sell Tuning the AFM out at cost but they wouldn't even go for that.
Unfortunately....This one is going to have a Workmanship ONLY warranty as I can't stand behind used parts.
I am going to replace the 2 outboard exhaust manifold bolts with ARP's for free just to mitigate them shearing off.

Not to be confused when BOTH Rockers on a AFM Cylinder Deactivating when not commanded to.....That's classic symptoms of a VLOM Control Solenoid stuck open.

Pic of the 2008 LMG torn down, Ready to pull the Camshaft....
02ElQPO.jpg



Video of the 2011 L9H #7 AFM Intake Lifter Deactivating itself......
 
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OVERKILL

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#5 piston is close to the top of the bore....You're seeing the piston crown reflection on the cylinder wall.
OK, that assumes I got my SBC cylinder numbering correct, lol. The visible piston top in what I would refer to as #1 is quite ashen in colour, as is #6, while #2 and #5, where I assume I am seeing bore, has some amber hue to it:

02ElQPO.jpeg
 

OVERKILL

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I changed my post because I saw what you saw :), You can now see the difference after I cleaned everything up.

Yep, looks a lot better! Does look like there MIGHT be a bit of a varnish ring around the top though? Is this one of the cylinders where the AFM was buggered?
 

clinebarger

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Always change the Cam Thrust Plate as it seals the 2 oil galleys that run along the Cam Bore...The seal has a tendency to leak causing low oil pressure at hot idle.

I eliminate the Spring Loaded Timing Chain Tensioner as they're failure prone, This requires use of a Gen III/Early Gen IV Timing Chain. The LS2 Timing Chain Damper isn't necessarily required but reduces Chain Harmonics prolonging Chain life.

Using a Gen III 3-Bolt Cam requires use of a 3-Bolt Timing Gear.

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clinebarger

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Yep, looks a lot better! Does look like there MIGHT be a bit of a varnish ring around the top though? Is this one of the cylinders where the AFM was buggered?

Neither #2 or #5 are deactivated cylinders, AFM cylinders are #1, #4, #6, & #7.

I got all the piston off TDC so I could clean the decks as the pistons sit proud when at TDC....#5 is pretty close to the top in this photo.
#2 does look a little darker but I think that's something to do with my Camera & my underhood work light causing shadows.
The bore condition looked pretty even in real life.
I do a leakdown on all cylinders before removing the heads cause the last thing I want is to do this twice! The were pretty uniform!

All the cylinders have a strip of carbon at the top of the bores, This is normal on a engine with 50,000 miles much less a 200,000 mile one like this.

oKZwMr8.jpg

kaydBKY.jpg
 

OVERKILL

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Neither #2 or #5 are deactivated cylinders, AFM cylinders are #1, #4, #6, & #7.

I got all the piston off TDC so I could clean the decks as the pistons sit proud when at TDC....#5 is pretty close to the top in this photo.
#2 does look a little darker but I think that's something to do with my Camera & my underhood work light causing shadows.
The bore condition looked pretty even in real life.
I do a leakdown on all cylinders before removing the heads cause the last thing I want is to do this twice! The were pretty uniform!

All the cylinders have a strip of carbon at the top of the bores, This is normal on a engine with 50,000 miles much less a 200,000 mile one like this.

oKZwMr8.jpg

kaydBKY.jpg
Yep, no worries, I know the ring at the top is normal, it just looked a bit more "band-ish" in the earlier pic, but your closeup shows I was just seeing the piston top.

Yes, #2 does look slightly discoloured, which is interesting but inconsequential given your test results.
 

clinebarger

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GM Performance "Bowtie" Lifters, Yes.....They are expensive at near $400 for the set, But they are the BEST lifters for this engine in my opinion.
Soaked them in some 10w30 Synthetic oil before installing them with new Guide Trays.

Nobody local had GM OE 5.3L specific Head Gaskets, 5.3L/5.7L "hybrid" gaskets were readily available.....But I don't care for enlarged I.D. reducing Quench. Fel-Pro Perma-Torque gaskets had the correct bore opening so that's what I used.

This engine had @15 PSI of oil pressure at hot idle, To shore this up, I'm running a High Volume Melling Oil Pump, There IS a cheaper one that doesn't have the Black Anodized coating.....But, Again....None were in stock locally.
Swapped the Red high pressure spring for the Standard Pressure Blue one.

vaQ7Stf.jpg

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totVUBx.jpg

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clinebarger

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I did check the AFM Solenoid Screen/Thimble Filter before settling on a HV oil pump. This filter can clog up causing low oil pressure gauge readings.
I also visually checked the Cam Bearings with a Bore Scope....They're in surprisingly good shape for the mileage.

This filter does not go back in.

Didn't mention that this thing reeks of frustration with all the parts that have been shotgunned in.....Coils, Plug Wires, Injector on #4, Intake Gaskets, 7 of the plugs are new Delcos.....#4 has a NGK Iridium plug in it.
All the while it had very audible Lifter Tick!


9M2TbYx.jpg
 

clinebarger

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Update on the 2011 Denali Yukon XL, The #7 Intake Lifter was spinning in it's bore from a broken Lifter Guide Tray. Thankfully....The Camshaft is no worse for wear & was able to swap the 8 Lifters & the 2 Trays on that bank out for low mileage used ones.

Actually.....I had my "new hire" 2 year apprentice mechanic do the work on this one. Very proud of him for taking instruction & NOT complaining about working on a Saturday. He doesn't know he made $300 today.
 
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Update on the 2011 Denali Yukon XL, The #7 Intake Lifter was spinning in it's bore from a broken Lifter Guide Tray. Thankfully....The Camshaft is no worse for wear & was able to swap the 8 Lifters & the 2 Trays on that bank out for low mileage used ones.

Actually.....I had my "new hire" 2 year apprentice mechanic do the work on this one. Very proud of him for taking instruction & NOT complaining about working on a Saturday. He doesn't know he made $300 today.
He is lucky to have you for a teacher.
 
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I did check the AFM Solenoid Screen/Thimble Filter before settling on a HV oil pump. This filter can clog up causing low oil pressure gauge readings.
I also visually checked the Cam Bearings with a Bore Scope....They're in surprisingly good shape for the mileage.

This filter does not go back in.

Didn't mention that this thing reeks of frustration with all the parts that have been shotgunned in.....Coils, Plug Wires, Injector on #4, Intake Gaskets, 7 of the plugs are new Delcos.....#4 has a NGK Iridium plug in it.
All the while it had very audible Lifter Tick!


9M2TbYx.jpg
Is this the screen mounted at the top rear of the engine?
 
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