Big Blue: 2005 GMC Yukon Denali

[Jake]

Mileage: 132,450

Rotated the tires front-to-rear over the weekend. Obvious conclusion: 20" wheels with big tires are heavy. I will need a set of tires over the summer sometime as the fronts are from 2010 and rears from 2011, both with diminishing tread.

Dropped 'er off at the local shop on the way in to work today. The "few drips of oil" overnight in the driveway have turned into "many drips of oil" overnight in the driveway. Not something I want to deal with right now (VIR coming up this weekend, moving the next) and I need this to be turn-key-no-bullshit for the next three weeks or so before I will have time to work on it myself.

I poked around when I changed the oil a few weeks ago and couldn't reach any solid conclusions. It's either the oil pan gasket, the oil pressure sender o-ring, or the oil cooler line(s) leaking. Currently awaiting a call with diagnosis (or maybe they'll just call and be like "yep all done," given I told them to just fix whatever).

She's also going to need brakes done soon. Going with some Performance Friction pads (thanks, Wonger) as I've been pleased with their .08 compound on the M3 and a street-friendly PFC pad for the Denali is $60 per axle. Typical "cheap from RockAuto" rotors will be used, and I ought to get new brake fluid in there too. That'll be a project to tackle once I get moved, though.

[Jake]

Mileage: 133,300

I've never had a truly legitimate use for this large of a C-clamp before:



Did the front brakes though, and it came in awfully handy to compress the caliper pistons. Front brakes are dual-piston which I thought was neat. I'd never worked on a multiple-piston caliper before so compressing them was interesting. Compress one and the other extends more. It was frustrating until I went back and forth a few times and got them both compressed enough to slide everything back onto the rotor.

This was my first car job in the new garage - moved to Alexandria a week ago - and while the truck does fit in there for temporary work, it's... tight.



I put Performance Friction pads and new (cheap, from RockAuto) rotors on the front. Will do rears at some point. Also need to put new brake fluid in it eventually. It stops much better now, but the pedal is still spongy at times.

Old vs New:



Awwww yiss.

[.RJ]

Use the old pads in the caliper to compress the pistons.

[Jake]

Use the old pads in the caliper to compress the pistons.

Good call.

[Senor_Taylor]

Rear disc or drums?

[Jake]

Rear disc or drums?

Four-wheel discs.

[Senor_Taylor]

LA DI DA. Look at Mr. FANCY PANTS over here with his disc brakes.

[Jake]

LA DI DA. Look at Mr. FANCY PANTS over here with his disc brakes.

Yeah man, the Denali trim level got you all the chrome, ever and rear discs.

Pedal feel still sucks. I think I need to bleed the system with new fluid.

[Jake]

Well, it's been 10k miles of ownership so I figured I'd sum up how things have gone so far.

Driving Impressions
For being a giant American land yacht, it drives better than it ought to. The Magneride and rear air ride keep it pretty composed. The ginormous V8 makes really good noises and I kind of want an intake or something for it. The transmission is dimwitted but generally does its job without much banging and clanging around. Every so often I catch it off guard and it WHUMPs its way into a gear it didn't initially expect.

Towing Impressions
Fantastic. Gearing is marginally shitty when leaving a red light - that 1st to 2nd ratio change means you really need to wind out 1st if you want to keep up with traffic - but otherwise it does well. 13ish MPG towing at 70 mph is not all bad IMO. I'm glad I got something this size vs. an X5 or Touareg. It sucks a little bit to daily drive but is very stable when towing at higher speed.

Repair Costs
It's needed new front brakes ($100 for PFC pads and RockAuto rotors) which I did myself, and valve cover gaskets ($250 parts + labor) and a steering box ($500 parts + labor) that I did not do myself, either because of laziness or a lack of time. Oil changes are done per the dashboard notification and seem to come up every 6k miles. There's a lot of room to work on things.

What's Broken
It leaks oil and power steering fluid and thus needs an oil pan gasket and, well, I gotta figure out the P/S leak. I'll do both of those repairs myself. It'll also need a set of tires by the end of summer. I'm looking at roughly $800 in tires which is less than I thought I'd be spending. The tires on it now are super old so hopefully the replacements will last an equally long time.

Oh, and the rear HVAC is stuck on "very warm" because a stupid plastic piece that controls the hot/cold blend door for the rear broke off. If I get a sudden burst of motivation and find myself with an abundance of time, I'll rip apart the HVAC box and fix it. But the front vents work fine for air conditioning, and the heat works throughout the entire cabin, so... not a priority.

In Summary
I wanted to make a Euro SUV work, badly, for my needs. Everyone managed to convince me to try a giant American pickup-based variant instead. It had nasty panel gaps when it was brand new, it has an abundance of plastichrome on every surface, literally everything rattles when you hit a pebble on the road, the drivetrain is as advanced as a #2 pencil, and I thought I'd hate this Yukon because of those things.

But, I don't. It's fantastic. I don't like the newer ones nearly as much, but I understand why you see sooo many GMT800 SUVs and pickups on the roads still. I grew up riding around in a few - several friends' parents had various Tahoes and Yukons and Suburbans - and even with all the typical "GMisms" that the platform exhibits, it somehow "works" really well.

[ScottyB]

Jake, i don't generally ever recommend putting snake-oil stuff in a car but for the P/S leak, try topping it off with Lucas power steering stop-leak.
<!-- m --><a class="postlink" href="http://lucasoil.com/products/problem-solvers-utility/lucas-power-steering-stop-leak">http://lucasoil.com/products/problem-so ... -stop-leak</a><!-- m -->

our xterra is dry-rotting/splitting at a lot of P/S hose junction due to over-tightened factory collars causing minor drip leaks. i topped the resivior off with that stuff because, hey, its better than spending $200 on new lines/hoses. sure enough, no problems since, and its not enough stop-leak in the system to make me believe i'm stressing the pump with super thick fluid. i think its got some detergents in it that make the rubber swell which also helps.

[Jake]

Over the weekend, I attempted replacement of both power steering hoses. The P/S setup on this truck is goofy because it was adopted from the diesel 1/2-ton trucks and doesn't match up with other Tahoes/Yukons. Yay Denali. Heyyy Macarena.

The power steering and power brakes work off of this system called Hydroboost, which basically uses hydraulic assist from the power steering to provide power assist for the brakes.

So, the brake booster up at the firewall is mounted to this big metal unit that is doing all of the Hydroboosting, and that lets me both turn and stop. Kinda imperative that I make it work right. There is a line that comes from the P/S pump to the Hydroboost, and another line that goes from Hydroboost to the P/S box. Both lines were leaking. New AC Delco lines from Rock Auto were $40 total. Yay, GM.

The line that goes from the Hydroboost to the steering box was pretty simple to replace. Just had to remove the air intake to get enough space for my arm + wrench.

I didn't get the other line (Hydroboost to pump) replaced, as I can't figure out how to get the old line off at the pump. It's mounted to the back of the pump, which means you can't access it from the top of the engine bay - too many hoses and brackets in the way. I can get a wrench on it from underneath the truck, but then I've got the pitman arm and other steering/subframe jank in the way, so I can't actually turn the wrench at all.

The leak is slowed down by the replacement of the one hose, but the other is definitely leaking as well. I may have to get creative. I think someone on a Yukon forum mentioned removing the front left wheel and wheel well liner, and that providing easier access.

[D_Eclipse9916]

Crow's feet if you are really in a pickle. I hate using them though.

[Jake]

I'm going to write a book and call it Creaks 'n' Leaks: The Saga of Hydroboost. It'll sell tens of copies.

So like I said, I replaced the one Hydroboost line but the other was too hard to remove at the time. The plan was to re-attempt surgery at a later date, and then naturally the line failed in a pretty catastrophic manner the night before I was going out of town. Thankfully, it wasn't a driving trip, but I was busy as hell... so I dropped the truck off at the local shop I use and asked that they replace the line. Done.

They said they cleaned up the subframe and everywhere that was sludgey from leaks, replaced the line, and "topped off" the P/S reservoir. It drove well for ~100 miles and then started making that hateful-cat-howl noise from the pump again.

Checking the fluid at the time revealed it was still full in the reservoir. The noise went away and came back again last night when I got home from trivia (naturally, super late, in the dark) and this time, the reservoir was dry. I added more fluid and that calmed it down for my drive to work today.

The cap (and P/S reservoir bracket) are both damp which to me indicates fluid spewing out of the cap. Hydroboost seems to be sensitive to air bubbles in the lines. I called the shop and they confirmed they "topped off" but did not "bleed" the system... I think it needs to be bled, badly.

Am I right in thinking that some air bubbles could cause the random loud howling, and as the air works its way out of the system, it'll gulp down more fluid? The system doesn't seem too difficult to deal with, but given it controls both my steering and brakes, I'm slightly skittish.

[navin]

I looked up some threads on Hydroboost real quick and it basically seems like you are on the right track. Bleeding it seems pretty simple:

1. Replace any hydraulic line showing external damage. Rubber hoses more than 4 years
old should be replaced. Install new seals for all disconnected fittings (as required) and
install an in-line power steering filter. Tighten all hose fittings to OE specifications.
2. Flush the entire power steering system using the vehicle manufacturers recommended
fluid. Fill pump reservoir to the proper level.
3. Disable engine to allow cranking without starting. Block wheels, put transmission in
neutral or park and set parking brake, then crank engine 5 to 10 seconds (avoid
overheating starter motor).
4. Refill pump reservoir as necessary. Repeat step 3 until level is correct.
5. Enable the engine to allow starting. Start engine and let idle. Slowly turn steering wheel
from lock to lock a number of times.
6. Turn engine off and inspect fluid level and condition. Add or remove fluid as necessary. If fluid
is foaming, wait one hour then recheck level. Repeat step 5 and 6 until fluid level is correct
and shows no sign of air. If the problem persists recheck installation and connections.

[ScottyB]

hateful-cat-howl noise from the pump again.

:lol: should have left it alone just for the amusing noises

first image that flashed through my brain


thanks internet.

[Senor_Taylor]

I looked up some threads on Hydroboost real quick and it basically seems like you are on the right track. Bleeding it seems pretty simple:

1. Replace any hydraulic line showing external damage. Rubber hoses more than 4 years
old should be replaced. Install new seals for all disconnected fittings (as required) and
install an in-line power steering filter. Tighten all hose fittings to OE specifications.
2. Flush the entire power steering system using the vehicle manufacturers recommended
fluid. Fill pump reservoir to the proper level.
3. Disable engine to allow cranking without starting. Block wheels, put transmission in
neutral or park and set parking brake, then crank engine 5 to 10 seconds (avoid
overheating starter motor).
4. Refill pump reservoir as necessary. Repeat step 3 until level is correct.
5. Enable the engine to allow starting. Start engine and let idle. Slowly turn steering wheel
from lock to lock a number of times.
6. Turn engine off and inspect fluid level and condition. Add or remove fluid as necessary. If fluid
is foaming, wait one hour then recheck level. Repeat step 5 and 6 until fluid level is correct
and shows no sign of air. If the problem persists recheck installation and connections.

1. Replace Hoses
2. Bleed system

[Jake]

Update on the Hydroboost BS: had to replace the master cylinder. That was a fun shop bill. It's finally stopped spewing fluid everywhere though, which is nice.

Need to get my tires installed this week or next as it's due for VA safety inspection and the old tires are pretty shot.

And naturally, since it's due for inspection, the horn quit working on Sunday.

It still honks when I lock the truck, or hit Panic on the remote, so my guess is that the ground wires and/or contact points between the airbag and horn ring are a little fucked up. Going to pull the airbag tonight and clean it up. Some Googlefu makes it sound like a common enough problem.

[D_Eclipse9916]

Update on the Hydroboost BS: had to replace the master cylinder. That was a fun shop bill. It's finally stopped spewing fluid everywhere though, which is nice.

Need to get my tires installed this week or next as it's due for VA safety inspection and the old tires are pretty shot.

And naturally, since it's due for inspection, the horn quit working on Sunday.

It still honks when I lock the truck, or hit Panic on the remote, so my guess is that the ground wires and/or contact points between the airbag and horn ring are a little fucked up. Going to pull the airbag tonight and clean it up. Some Googlefu makes it sound like a common enough problem.

:? I never had any of these issues on my truck. Out of almost 3 years all I did was replace oil, rear shocks at 110k and an alternator.

[Jake]

:? I never had any of these issues on my truck. Out of almost 3 years all I did was replace oil, rear shocks at 110k and an alternator.

Yours was younger at the time... I'm at 10 years and 138k miles, stuff's just going to go wrong.

[Jake]

Well, I pulled the airbag off (super easy, it's spring-clipped into the steering wheel) and one of the two ground wires for the horn was kinked just so that it wouldn't work. I un-kinked it, routed the wires a bit differently so they won't get smushed again, and it works now.