Big Blue: 2005 GMC Yukon Denali

[Jake]

Mileage: 142,500

The truck did great on the Road Atlanta trip. Right about 1,300 miles and didn't skip a beat. Managed 12.x mpg throughout the journey, which I was happy with given how hilly parts of that drive can be.

It threw a CEL as we were filling up to leave NoVA (really). My Bluetooth OBD II adapter wouldn't connect to the ECU so I said "screw it" and we did the trip with the light on. Did some reading once I got home and I guess all cheap Chinese Bluetooth adapters are not created equal, and some of the worst offenders have a hard time with Ford and GM ECUs. No idea what makes one $20 adapter better than other $20 adapters, but the one to have is by "BAFX" and is $23.

That showed up this morning so I pulled the code - P0499 which is for the evap canister "vent solenoid". I cleared it and am going to see if it comes back before bothering to order anything. When I initially saw the CEL light up, I checked the gas cap and it was a bit loose (had just filled up) so maybe that's what set it off.

In other news, time to fix more shit! I got the ol' girl through the track season and now it's time to fix a few little things that I've been ignoring.

• Valley pan gasket - it's leaking oil down the back of the motor. DIY looks like a simple enough job, actually.
  
• Intake manifold gaskets and knock sensors/harness - since they come off for the valley pan, do 'em.
  
• Center diff/transfer case/whatever (AWD) is leaking a teeny bit. Enough to make me uncomfortable but not panicked. Going to have a friend (full-time Toyota tech, loves side work, is not Jason) do this one.
  
• Trans fluid drain/fill - it was done 40k ago and with so much towing... might as well.
  
• Rear brake pads/rotors have a few months left, but should be done before my next tow
  
• Brake fluid is this disgusting, vile color and may be from 2005. Doing this one ASAP.

So, not all bad... just little stuff to take care of. The GMT800 trucks are notorious for rusting brake lines, so I checked mine yesterday - just follow 'em along the frame rail. A bit of surface rust on mine, but nothing worrisome, so that's good.

Still love this leaky, rattly old GMC. No plans to sell it anytime soon.

[Jake]

Mileage: 142,800

I decided that I'd take advantage of the oddly nice weather to attempt a few fixes on the Denali before winter really sets in.

First up, while "working from home" last week, was the evap system "vent valve solenoid." I had a code for it and it's $20 from Amazon for an AC Delco replacement. The part is clipped on to the charcoal canister, located above the rear diff and axle. Two bolts let the canister swing down, which gives you plenty of access to the solenoid.

The entire internet warned me about the plastic tube that you have to disconnect and "OMG you will break the clips, make sure you have spare rubber hose and clamps to replace it!!" Well, if you take more of a James May approach vs. Jeremy Clarkson, you can remove the tube and use it again. It's just some plastic clips that need a gentle touch to remove. I used a small pick and some patience and it worked.

The offender:



I cleared the CEL and it came back after a few ignition cycles. Some Googling reveals a second Evap solenoid thing near the throttle body. It's similarly cheap, and people claim that often the truck will throw the code for one when really the other is bad. So, I guess I'll do that eventually.

Next up - the valley pan of doom.

I say that only because this was an intimidating job until I started on it. I had helped Joey work on Lauren's E39 540i as her valley pan gasket was leaking a few years ago. We had to remove all sorts of crap to get at the valley cover, and it still leaked when we were done. So, that was the "experience" I was going in with.

Really though, it wasn't bad. I found a great DIY that showed how to replace the knock sensors, which is 95% of the job.

Basically... remove airbox and throttle body. Drain and unclip fuel line. Unplug injectors (by far the biggest pain-in-the-ass of this entire job). Unplug some other stuff. Unbolt the intake manifold and remove it.



The knock sensors are under these styrofoam-y covers. Pull those up with a small pick, unclip the harness and then unbolt the knock sensors with a 22mm deep socket. Admire the copious amounts of sludgey shit on the valley cover as you do so, perhaps from a leaky valley cover gasket.



Now unbolt the valley cover and carefully (again, use a pick and/or flathead screwdriver... carefully) pry the cover up. It'll probably be stuck due to aforementioned sludge. You may have to find a stepstool to achieve proper leverage when removing the cover:



Odd thing - when I unbolted the valley cover, about half of the bolts holding it down weren't even finger tight! The torque spec is low - something like 10 in-lb - but I didn't even have to use a wrench to unbolt them. Maybe that's why it was leaky.

Death Valley:



Old gasket and nasty valley cover. I cleaned the cover up with Brakekleen and used a new Victor Reinz gasket.



Put everything back together (valley cover bolts are effectively "snug" torque, knock sensors are 15 ft-lb which is also "snug" and so is the manifold. Be careful.), reconnect the various electrical connections and vacuum lines you pulled, and start 'er up.

I'm now facing a fun quirk - the drive to work this morning was my test drive - when the motor warms up, it gets a bit of a bouncy idle (varies by 200 rpm ish) and the dash lights pulse. Kind of seems like an odd vacuum leak, so I need to check the hoses I pulled. Fortunately, I only pulled a few of them so I'm hoping I can find it easily enough.

[Jake]

Found the "quirk" in the form of a vacuum line that must have pulled itself off when I was getting everything back lined up:



Truck idles fine now.

Still leaks a fuckload of oil. Argh. I looked underneath it last night and am kind of wondering if the shop that told me my valley pan was "catastrophically leaking" when in fact it was kind of a seep, actually did the work they said they did. They claimed to have replaced the oil filter plate gasket, but looking at the truck, it's super wet right there and farther up the motor looks pretty dry.

[HAULN-SS]

I always have to use a step-ladder to work on the F250..pain in the ass, and hard to get any leverage on anything. Ground work sucks too, because my jacks are all maxed out to get the tires off the ground. Bah.

[RawrImAMonster]

The victor reinz valve cover gasket I just put into my M3 leaks too. I even took it apart a second time cleaning the shit out of everything and using RTV along the bottom where it leaked, didn't help. I'm going to replace it with an OE one eventually. After doing some reading, I found this was a fairly common issue with this brand, at least on my car.

[Jake]

The victor reinz valve cover gasket I just put into my M3 leaks too. I even took it apart a second time cleaning the shit out of everything and using RTV along the bottom where it leaked, didn't help. I'm going to replace it with an OE one eventually. After doing some reading, I found this was a fairly common issue with this brand, at least on my car.

Oh, this leak doesn't actually appear to be coming from the valley pan. I did this work trusting that a shop's diagnosis was correct... and I am not so sure now. The leak is lower than the valley pan/valve covers from what I can tell.

VR has always been good for me, I've used their valve cover gaskets on BMWs for years. I did go with an Elring head gasket on the M3 versus VR as I heard better things about Elring for that application.

[Jake]

One Year of Denali

Well, it's been a year of ownership as of today. I've put 18k miles on the big blue beast which surprises me a bit, but I suppose when you have something that is exceptionally good at towing and going on road trips, it lends itself to many miles of just that.

Ownership costs have been somewhat significant, in part due to things failing and in part due to maintenance needing performed.

The "Expected" Stuff

• Tires, set of 4
  
• Front brake pads/rotors
  
• A few oil changes

The "Ugh This Is Getting Expensive" Stuff

• Tie rods
  
• Steering box
  
• Hydroboost lines
  
• Hydroboost master cylinder
  
• Valve cover gaskets
  
• Valley pan gasket
  
• Intake manifold gaskets
  
• Knock sensors + harness

Overall, even though it's been a bit of a pain to own at times, it's still far cheaper than owning a brand new truck equipped to a similar standard. I did (*gulp*) tally up the cost of maintenance for the first year, and it was pretty staggering.

I'm really unsure of what I want to do with this truck. It's still leaking oil (which I need to have addressed regardless), the transmission fluid should be drained/filled, the transfer case is seeping a little, and I'm super concerned with the brake lines, which are known to rust from the inside out, and then *kabloom* you have no brakes.

Between the (small) loan I have on the Denali and the averaged monthly maintenance cost... I could be rolling around in a 2012ish F-150. That wouldn't leak stuff and wouldn't blow out a brake line in a panic stop.

So... my thought is to have the oil leak fixed and trans fluid done. And from there, I truly am not sure what I want to do.

Evap CEL Update
If anyone recalls (or cares) I replaced the evap canister/solenoid at the rear of the truck, in an effort to rid myself of the P0499 code. The code came back after a few ignition cycles, so I replaced the purge vent solenoid under-hood, as some folks said it could be that solenoid throwing the same code. That also didn't work, and someone on the Yukon forum suggested looking at wiring where it plugs into the solenoids. That got me thinking...

When I took it to Road Atlanta in early December, my trailer had some wiring that was grounding out against the frame and blowing the truck's fuse for the trailer running lights. I blew through a few spare fuses as I was diagnosing that wiring and ran out of legit spares... so I thought it was so kind of GM to leave fuses in the box for options my truck doesn't have.

The first two fuses I pulled to use on that circuit were for L/HID and R/HID as the Denalis don't have HID headlights.

The third and final fuse? 4WS, because the Denali never got 4 Wheel Steering/Quadrasteer.

Well, the post about wiring got me thinking - this evap stuff has to be on a fused circuit, which one is it? Fifteen seconds on Google got me the answer.

I guess someone at GM decided that the evap system and Quadrasteer could share a circuit, and that it was smarter to label the circuit with the rare option vs. the standard emissions system.

So... I'll be putting a new 15A fuse in the 4WS spot and that ought to, you know, let the evap solenoid do it's thing.

[WRXtranceformed]

Wow that is interesting to hear about the cost of ownership, I guess that is the conundrum with an older vehicle especially one you are towing with and driving a lot. It sounds like you are figuring out what you want to do with it, which direction are you leaning? Is it holding its value well? It would be nice to find a vehicle under warranty if you can find one to tow with and basically net out what you are spending on this one now.

[Jake]

Wow that is interesting to hear about the cost of ownership, I guess that is the conundrum with an older vehicle especially one you are towing with and driving a lot. It sounds like you are figuring out what you want to do with it, which direction are you leaning? Is it holding its value well? It would be nice to find a vehicle under warranty if you can find one to tow with and basically net out what you are spending on this one now.

Yeah, I mean, it's about what I expected for "first year" type of stuff. Everything I've done to it this year should not need re-doing for 2016 or 2017.

The driveline is all very solid. I think the smartest thing to do financially, since it seems like I'm "over the hump" of getting it sorted, is to drive it for another year and try to amortize the costs of 2015 a bit. And I do really just like it. It's a good size, drives well, has a good interior layout, etc.

That said, if the transmission starts flaring between shifts or anything else "telling" starts happening, it'll be traded ASAP. I've put "big money" into it in 2015 and don't want to do that for a second year.

Value-wise, it's holding it well enough that I could sell it and not feel bad, if it came to that.

[HAULN-SS]

I think you must have miscalculated, or you got really ripped off if this is anywhere near the cost of a 7+year newer F150. Unless you're talking about a work truck edition or something similar.

[Jake]

I think you must have miscalculated, or you got really ripped off if this is anywhere near the cost of a 7+year newer F150. Unless you're talking about a work truck edition or something similar.

You can be driving a lot of truck for $500/month. Not brand new, but a 2012 Lariat with 30k miles? Sure.

Anyway. Did some thinking and decided that "the devil I know" is better than the devil I don't. Going to have the leak fixed, the transmission serviced and keep on rocking for now. A newer truck would also mean higher property tax and increased insurance cost, both of which are cheap on a GMT800.

I think summertime will be a good point to re-evaluate - give it six months and see how the truck is doing and how I'm doing financially. If it can stay reliable, I have no problems keeping it another few years as I do really like it.

[Jake]

Well.

Took the truck to "my guy Gary" and he hit me with some news that has changed my tune.

The oil leak is from three places - rear main seal, oil pan gasket, and oil cooler lines. That's a tremendously expensive set of repairs. It'll also need a transmission service (just drain/fill and new filter) which is a few hundred bucks. And even if I had all of that done, I have to worry about the front diff grenading (common on the AWD GMs) and brake lines exploding (common on all GMT800s).

I am currently in the market for a newish (2011+) F-150 or Ram 1500 and will either be selling or trading this.

[ViPER1313]

Or you can just add oil... Oil is cheap

[HAULN-SS]

That's what I was thinking. Just dump some pepper in your valve covers and faggeddaboutit

[WRXtranceformed]

Just dump some pepper in your valve covers

Is that a real thing?

[HAULN-SS]

Kind of kidding, but it's a supposedly tried and true way to stop headgasket and radiator leaks

[Jake]

It'd be different if I were just commuting in it 6 miles each way, like I do in the convertible.

For something I depend on for long drives with a trailer in tow? Eh, do it right or not at all.

[ViPER1313]

It'd be different if I were just commuting in it 6 miles each way, like I do in the convertible.

For something I depend on for long drives with a trailer in tow? Eh, do it right or not at all.

How much is it leaking? Is it leaking on anything that gets hot or just falling on the road?

[Jake]

It'd be different if I were just commuting in it 6 miles each way, like I do in the convertible.

For something I depend on for long drives with a trailer in tow? Eh, do it right or not at all.

How much is it leaking? Is it leaking on anything that gets hot or just falling on the road?

I'll take a photo of my driveway.

[D_Eclipse9916]

It'd be different if I were just commuting in it 6 miles each way, like I do in the convertible.

For something I depend on for long drives with a trailer in tow? Eh, do it right or not at all.

How much is it leaking? Is it leaking on anything that gets hot or just falling on the road?

I'll take a photo of my driveway.

Go buy a tundra you hippie. I heard they are awesome. :wink:

Sorry to hear bout your bad luck. I put all of $300-400 into my Denali over 2.5 years from I think 80-120k miles and was in immaculate shape when I sold it. Yours and Chris Davies experiences differ from mine and Simons, maybe blue cars are cursed?

Sell it, go buy a brand new truck and don't think about it. That eco-diesel Laramie Ram at $35k new is quite tempting for someone wanting to tow an open trailer or small enclosed.