First year ownership and 5K miles 2011 Yukon Denali

[MWD_CTSV]

I'm looking at my recent NC safety emissions report and it is 5K miles (219K) since I had it inspected last year at 214K miles. I actually had to get a 10-day tag and pay a fine to take it for inspection because it was 2.5 months from when I bought it and past due for inspection.

I'm not really a truck person, although I have owned a 1974 Bronco for 30 years, but all others are uni-body. Well ok, not the Factory Five, but it isn't a truck.

The GMT900 platform has really grown on me. At nearly 220K miles, it really surprises me how young it really feels, and how the platform feels like a 500K mile design (with maintenance). It still is a truck, but it drives well, cruises well, has good power, holds lots of passengers with plenty of space, tows well, and is well a huge amount of carrying capacity. I moved kids into a college dorm and a college apartment last summer with one trip each, and there was room left over. We took an exchange student, my wife, 3 of my kids and 5 bikes on a long weekend through the VA/NC/TN mountains and everyone was comfortable.



Maintenance replacements (not necessarily needed but preventative lets say):

Engine/Trans:
-GM radiator
-GM transmission cooler hoses
-GM oil cooler hoses
-AC Delco water pump
-GM Coolant hoses
-GM heater hoses & plastic Ts
-GM valve springs
-BTR trunnion bearing upgrade
-Plugs & wires
-Passenger coils
-Intake/Exhaust gaskets
-AFM/DOD delete
-OSC PVC oil separator
-Passenger motor mount H3 upgrade
-Denso O2 sensors
-6L80 rebuild
-Injector cleaning

Suspension:
-GM rear Z55 air shocks
-Dorman rear air pump
-Front Sway bar links

Upgrades:
-Black Grille
-LED headlights plus Diode Dynamics LED switchback turn signals
-Rear Brake/Backup LED bulbs
-3DS floor mats
-2022 PPV 6 piston front brakes (awesome)

Realistically only the valvesprings and rear shocks/air pump were the only true failures needing some attention, but I get a little carried away.

 

[MWD_CTSV]

So a little backstory....

My friend is looking for a used truck to replace his tired 2003 Ford F150 with something safer, but not too new that he is afraid for his 15 year old to drive it to school. Late 2022, he brings me a 2013 Silverado from the Northeast. Aside from the rust, I am pretty impressed overall with the platform. At $20K, I tell him he can do better, so I am scouring the internet for owner listed Silverados. I see a 2011 Yukon Denali pop up on Facebook with 214K miles for $6K, listed as a mechanics special that has a failed lifter that has an estimated replacement cost of about $2.5K. So I do the research into the AFM/DOD lifter colllapse problem, and put it on the back burner. Well 2 weeks later the listing is still up, so curiosity gets the best of me and I arrange to go take a look. My friend has already found a local NC owned 2015 F150 for $15k, so he is happy, but this Denali is still on my mind. The vehicle has good bones so to speak, and nothing seems to be wrong other than the missing cylinder, so I tell them they should fix it since it would be better to invest a small amount in an otherwise good vehicle. But they have already bought another Yukon, so I think for a minute and offer them $5K, which they are happy with.

I bring it home and order the crazed performance lifter tool and DOD delete ring full prepared to try and unlock a stuck lifter without removing the heads. I am fully ok with removing the heads and replacing the lifters, but the idea of unsticking a lifter to have a potentially longer operational life without DOD for pennies, really intrigues me for some reason. There was active misfires on several cylinders as well as misfire codes plus an open circuit code for injector #2. So I start digging in with the ignition parts off and the intake removed, fully ready to unstick a lifter.

After I pull the valve covers, I find this:


I'm sure you can all spot the problem. A $4 valve spring. The previous owner was quoted $2400 to fix the problem. The open circuit on the injector was not a wiring problem, but just a diagnostic removal of the connector during previous troubleshooting. I guess it is also partly a miracle the spring broke on the lower section and didn't allow valve to piston contact. Crazily, I actually drove it about 15 miles home at low speed.

So long story short, the original lifters are still there. New valvesprings and a good injector cleaning and the engine runs like a champ.

 

[j91z28d1]

did you leave the afm active or deactivate?


I can't help be be curious how same go 200k working and some sick at 100k and others eat non afm lifters. I get that oil plays a role, but the previous owners don't sound like car guys changing oil every 3k.

it's such a mystery to me. I just hope mine is more on the 200k side haha

 

[Trey Hardy]

So a little backstory....

My friend is looking for a used truck to replace his tired 2003 Ford F150 with something safer, but not too new that he is afraid for his 15 year old to drive it to school. Late 2022, he brings me a 2013 Silverado from the Northeast. Aside from the rust, I am pretty impressed overall with the platform. At $20K, I tell him he can do better, so I am scouring the internet for owner listed Silverados. I see a 2011 Yukon Denali pop up on Facebook with 214K miles for $6K, listed as a mechanics special that has a failed lifter that has an estimated replacement cost of about $2.5K. So I do the research into the AFM/DOD lifter colllapse problem, and put it on the back burner. Well 2 weeks later the listing is still up, so curiosity gets the best of me and I arrange to go take a look. My friend has already found a local NC owned 2015 F150 for $15k, so he is happy, but this Denali is still on my mind. The vehicle has good bones so to speak, and nothing seems to be wrong other than the missing cylinder, so I tell them they should fix it since it would be better to invest a small amount in an otherwise good vehicle. But they have already bought another Yukon, so I think for a minute and offer them $5K, which they are happy with.

I bring it home and order the crazed performance lifter tool and DOD delete ring full prepared to try and unlock a stuck lifter without removing the heads. I am fully ok with removing the heads and replacing the lifters, but the idea of unsticking a lifter to have a potentially longer operational life without DOD for pennies, really intrigues me for some reason. There was active misfires on several cylinders as well as misfire codes plus an open circuit code for injector #2. So I start digging in with the ignition parts off and the intake removed, fully ready to unstick a lifter.

After I pull the valve covers, I find this:

View attachment 423493
I'm sure you can all spot the problem. A $4 valve spring. The previous owner was quoted $2400 to fix the problem. The open circuit on the injector was not a wiring problem, but just a diagnostic removal of the connector during previous troubleshooting. I guess it is also partly a miracle the spring broke on the lower section and didn't allow valve to piston contact. Crazily, I actually drove it about 15 miles home at low speed.

So long story short, the original lifters are still there. New valvesprings and a good injector cleaning and the engine runs like a champ.

Hell yea! I unstuck my lifters twice with marvel mystery oil my engine in the Tahoe is at 400,000 now

 

[MWD_CTSV]

did you leave the afm active or deactivate?


I can't help be be curious how same go 200k working and some sick at 100k and others eat non afm lifters. I get that oil plays a role, but the previous owners don't sound like car guys changing oil every 3k.

it's such a mystery to me. I just hope mine is more on the 200k side haha

I deactivated AFM in the computer and I inserted a blocking ring into the manifold to block oil pressure to the solenoids.

The window sticker showed this was sold through a local dealer. It was also sold as CPO around 100K miles, so it was clearly well maintained and the CPO purchase included an add-on for x number of oil changes. There were also receipts for synthetic oil changes in the glove box.

The owner I purchased it from had only had it less than a year, but they did say the previous owner had given them an oil pan gasket and suggested they replace it, which they did. I'm pretty sure this one had regular oil changes, which makes a huge difference. The cam lobes that I could see with the intake off looked very clean.

 

[j91z28d1]

I deactivated AFM in the computer and I inserted a blocking ring into the manifold to block oil pressure to the solenoids.

The window sticker showed this was sold through a local dealer. It was also sold as CPO around 100K miles, so it was clearly well maintained and the CPO purchase included an add-on for x number of oil changes. There were also receipts for synthetic oil changes in the glove box.

The owner I purchased it from had only had it less than a year, but they did say the previous owner had given them an oil pan gasket and suggested they replace it, which they did. I'm pretty sure this one had regular oil changes, which makes a huge difference. The cam lobes that I could see with the intake off looked very clean.

nice, I did the same mod to mine at 135kish. at 155 now. the car fax showed oil. changes ever 10k or so early in its life. unless they changed it in between and it was registered but it looks super clean inside. I just didn't want to take a chance. I also don't want to take to apart for a full delete haha.

looks like you got a deal. very cool

 

[petethepug]

That really sucks the previous owner got hosed by their shop. That shop probably ordered a new valve spring and spray paint for new looking heads that were never intended to be pulled.

The GMT900 are really predictable and owners tend to not maintain them. That’s a testament to their longevity because they tolerate the lack of maintenance and get sold on when they break. Kinda like you ran into

 

[MWD_CTSV]

That really sucks the previous owner got hosed by their shop. That shop probably ordered a new valve spring and spray paint for new looking heads that were never intended to be pulled.

The GMT900 are really predictable and owners tend to not maintain them. That’s a testament to their longevity because they tolerate the lack of maintenance and get sold on when they break. Kinda like you ran into

That is very true. I think the increased reliability can breed a lack of concern for maintenance. I also feel like some of these computerized maintenance minders imply that 8,000 miles is ok for oil change and maybe some will just think the yellow/orange light is more like a suggestion. It also makes it hard to determine true value for a used one.

I don't really blame the shop for quoting lifter replacement. It was a believable possibility to me, and I would probably give a quote for the most costly probably as well. Of course, if a shop charged for new lifters and simply replaced a valve spring and spray painted the heads, that would be very sad.

 

[adventurenali92]

Dang!!! you scored a really great deal on a nice truck and really bulletproofed it! I’d love to be able to do the same with a GMT900 soon! Nice work and thanks for sharing the journey with it! Really clean truck!

 

[Rwmullis79]

did you leave the afm active or deactivate?


I can't help be be curious how same go 200k working and some sick at 100k and others eat non afm lifters. I get that oil plays a role, but the previous owners don't sound like car guys changing oil every 3k.

it's such a mystery to me. I just hope mine is more on the 200k side haha

I’m about to roll over 240k in my 2011 Tahoe and my AFM is still active. One of the lucky ones I guess.