Purchased a 2007 Yukon XL, now to make it reliable!

that is an amazing amount of carbon build up and very even. (maybe it's more oil then hard carbon?) I'm kinda impressed haha. I've actually seen old Ford 300ci carbon knock with less build up. that's where the build up hits the head and sounds like rod knock or something.

Cylinder walls look OK and if it's running smooth, it must be OK. I do think I'd do the cleaning donjetman did plus add the 30$ catch can.

is this a flex fuel truck? if so and you have some local. e85 would probably clean those up in a few tanks. or atleast it would be a excellent test of it.

I feel like the plugs look pretty good after seeing the tops of the pistons. good you changed them but they hung in there.

donjetman said:

And check the GM service bulletin out:
https://f01.justanswer.com/ebrock63...il+Consumption,+MIL+ON,+Engine+Runs+Rough.pdf

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This is amazing, thank you!

j91z28d1 said:

that is an amazing amount of carbon build up and very even. (maybe it's more oil then hard carbon?) I'm kinda impressed haha. I've actually seen old Ford 300ci carbon knock with less build up. that's where the build up hits the head and sounds like rod knock or something.

Cylinder walls look OK and if it's running smooth, it must be OK. I do think I'd do the cleaning donjetman did plus add the 30$ catch can.

is this a flex fuel truck? if so and you have some local. e85 would probably clean those up in a few tanks. or atleast it would be a excellent test of it.

I feel like the plugs look pretty good after seeing the tops of the pistons. good you changed them but they hung in there.

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The cleaning being the new valve cover? Yes, it's on my list to get swapped.

It's hard to find e85, if not impossible. 91 octane is much more popular around here and that is most commonly carried. I just googled and it's like 180 miles away to find e85. I will check though next time I go into town.

Yeah those plugs were toast, probably the OEM ones is my guess.

YukonGold12 said:

The cleaning being the new valve cover? Yes, it's on my list to get swapped.

It's hard to find e85, if not impossible. 91 octane is much more popular around here and that is most commonly carried. I just googled and it's like 180 miles away to find e85. I will check though next time I go into town.

Yeah those plugs were toast, probably the OEM ones is my guess.

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Because of the original poorly designed driver side valve cover, my piston rings had stuck. I changed the valve cover to GM# 12570427, did the piston/combustion chamber soak, cleaned the ole crusty plugs, reinstalled them, and ran them another 40k miles. See post #1 and #19 here:
https://www.tahoeyukonforum.com/threads/sparkies-no-beno.108579/

I still have a catch can installed but it only catches 1-2 oz per 5000 miles. Before the valve cover change it caught 1 oz per 100 miles.

@YukonGold12
Techron fuel additive is effective stuff (WalMart, etc).

Alright, just took this beast to the Tetons/West Yellowstone. A total of about 600 mile trip for us. I am following up with some details and also some issues that I noticed on my trip and hopefully I can pick y'alls brains on some solutions.

@OR VietVet, for the first tank I used the Techron additive.
436 miles, got 16.6 MPG.
I was able to get e85 at a place out of state, this tank got me about 18.8 for 180 miles.

I haven't noticed any idling improvements, nor power just yet, but I am trying to pay more attention. I have noticed that I can feel the engine a good amount in the steering wheel. This might be just a non-issue and just not me being used to driving a v8.

Some issues I picked up on.

1. When braking down mountain passes. I get some vibration in the front. Feels like rotors, but as these were just changed, maybe something else? Maybe I got bad rotors. It feels like rotors though. I will need to get in there and check, maybe I need to check the pads to see if they are wearing correctly in the front?

2. When braking for a longer duration, typically seen coming to a complete stop and while the HVAC is on. The blower motor in the middle/passenger side of the dash makes noises. Almost grinding or like the bearings are bad. Might need to be replaced, but it's strange that it only happens when I am braking....

3. There is some interference, whining noises coming from passenger rear speaker. You can hear the whining when I accelerate/decelerate, and even some interference from the blinker at times. Turning the car off and on resolves the problem. It randomly occurs.

4. My mirrors are possessed . Basically, when I get into the truck or when I unlock it. The driver mirror goes crazy and attempts to adjust for some reason and just sits there whining, but the mirror doesn't move. These mirrors probably could be replaced.

Overall, this was a great trip and this thing is a beast. It didn't leave us stranded and just kept going. It holds a crazy amount of stuff which makes it super simple to get out and go camping.

Picture of everything loaded, bikes and everything!

for the rotors, what rotors did you go with and what break in procedure? there's something where the pad can deposit its material on the rotors and feel like it warped even if it's not. while I kinda write it off as an irrelevant theory since you can't undeposit it, so either you cut the rotors or replace them anyways. so it's basically the same thing, but it would explain why new ones feel that way when you haven't actually put enough heat in them to do damage. they say proper break in can avoid it, but honestly I've seen brakes do enough weird things, I just don't know anymore haha.


mirror i can only guess it's trying to move to a driver preset and since it's broken it can't get there. driver 1 and 2 can be set to different adjustments. when I hit unlock it moves to my settings if remote 2 was driving last.

rotors are likely warped some, sometimes it can go away on it's own depends on how you drive and/or how much material is on them. one way to check is to run your fingers across the surface of the rotors (not while they are hot) lol and see if it feels smooth or if they have ridges.

when traveling on extended downgrades I usually kick on tow mode, this allows the transmission to help slow you down and helps maintain speed/gear and therefore the brakes are not used as much and do not get heated up, versus riding the brake pedal all the time.

the blower motor can be checked fairly easily, just pull the cover off under the glove box, then it's 1 bolt and lift a clip up and the motor twist's and comes right out. The "fan" part should be firmly attached to the motor stem and it should not have any play at all. should just spin quietly by hand but not spin loose it will have a little drag.

the whining noise could be the radio or amp getting funky if the problem goes away with a key cycle

mirrors? does your yukon have memory buttons? like 1/2 on the door panel? if so it could be the mirror motor is out of whack and it's trying to go the set memory position but can't

j91z28d1 said:

for the rotors, what rotors did you go with and what break in procedure? there's something where the pad can deposit its material on the rotors and feel like it warped even if it's not. while I kinda write it off as an irrelevant theory since you can't undeposit it, so either you cut the rotors or replace them anyways. so it's basically the same thing, but it would explain why new ones feel that way when you haven't actually put enough heat in them to do damage. they say proper break in can avoid it, but honestly I've seen brakes do enough weird things, I just don't know anymore haha.


mirror i can only guess it's trying to move to a driver preset and since it's broken it can't get there. driver 1 and 2 can be set to different adjustments. when I hit unlock it moves to my settings if remote 2 was driving last.

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I went with the powerstop kit from Rock Auto. I have it listed on my spreadsheet here https://docs.google.com/spreadsheets/d/1GWTJEK0uzQ7C8TjYdxdeBgpUfOwHbz_1gknCLeX2QUc/pubhtml

The break in procedure I followed was in the kit itself. It was
30 stops from 30mph, with 30 seconds in between, I performed this for the front and the rear.

Doubeleive said:

rotors are likely warped some, sometimes it can go away on it's own depends on how you drive and/or how much material is on them. one way to check is to run your fingers across the surface of the rotors (not while they are hot) lol and see if it feels smooth or if they have ridges.

when traveling on extended downgrades I usually kick on tow mode, this allows the transmission to help slow you down and helps maintain speed/gear and therefore the brakes are not used as much and do not get heated up, versus riding the brake pedal all the time.

the blower motor can be checked fairly easily, just pull the cover off under the glove box, then it's 1 bolt and lift a clip up and the motor twist's and comes right out. The "fan" part should be firmly attached to the motor stem and it should not have any play at all. should just spin quietly by hand but not spin loose it will have a little drag.

the whining noise could be the radio or amp getting funky if the problem goes away with a key cycle

mirrors? does your yukon have memory buttons? like 1/2 on the door panel? if so it could be the mirror motor is out of whack and it's trying to go the set memory position but can't

Click to expand...

Yes, I will take off the wheels here today or tomorrow and check with my finger. I've already learned not to do that while they are hot!

I will take a look at the blower motor.


The whining certinally does go away if you cycle the key. It randomly shows up. Would that be a grounding problem as a good place to start?

Yes, but I am already realizing I think that the mirrors need to be replaced. The motors in them to move the mirrors just aren't working. The fold in feature also only works on the driver side. I've seen that these gears get stripped out and I believe they probably are for the interior housing as well. I will end up just getting new mirrors.