P/S pump talk

[Reprise]

Thought I was going to have to replace my p/s pump (after replacing hoses / gearbox and experiencing no assist at idle speeds even after bleeding; shop stated hydroboost was 'ok' and pump was to blame, when they were doing a wheel alignment today)

However, as I was later driving the old gearbox core to FedEx, and parking in their lot, I found the assist came back (for at least 2/3 of the steering wheel travel in each direction), along with the 'expected' noise from the pump as it's creating assist.

I'd like to think that (some of) the residual air finally bled out, anything left will eventually also bleed out, and I don't actually have to replace the pump (which isn't making unusual noises, and neither is the hydroboost module). Then there's a part of me that says this might be temporary, and the pump will 'fail' again. But I think (?) the pumps are fairly reliable, provided they don't run dry. I've never, ever had one fail in any vehicle I've owned, in my entire life (and that's a lot of vehicles, with several GM products in the list.)

Planning on taking the truck for an extended trip soon; I'll be 2000 mi. away from home & at the mercy of shops for any 'big' repair while on that trip (truck is otherwise reliable... knock on wood). I'll also be pulling a trailer, so I kinda need the full range of the power assist, not just the 2/3 or so that I have now. The brake assist was affected as well, as far as 'initial' engagement, but now also seem OK.

Did I dodge a bullet, or should I plan on replacing the pump? Thoughts?
(pump looks to be OEM; about 235K on it; it's in a HD pickup w/ the 6.0L gasser)

Also, FYI, the toe was way off, as I had replaced inner / outer tie rods (and also UBJs and the pitman & idler arms), so that might have affected things somewhat (binding?) But the drive back home from the alignment didn't seem to make the (lack of) assist any better... it was probably 30 miles and a couple of drive cycles later that the assist came back and started acting like normal.

 

[Mooseman]

I have found in the past that all air takes a while to work itself out of the system with some foam in the fluid. The pump could be on its way out but there isn't really a way to know for sure. I've usually gone with the telltale noise when it's dying. I've had new/rebuilt pumps do that out of the box. ACDelco has been my go to for these pumps for a while now.

 

[littleblazer]

When the brake booster failed in the escalade mom would drive the thing screaming pump and all... that went on for a year. Every time you added fluid it shut up and stopped screaming. They're pretty hard to kill even though I've had 3 in the trailblazer I've never replaced another one in anything else. The hydroboost setups are a literal pain to bleed once they run completly dry because everything stays locked in the brake booster. The best thing I've found is to get the front of the truck up really high and just keep going lock to lock on the wheel.

In other words, so long as you didn't torch the pump that bad, it's probably still fine.

 

[Reprise]

Hmm... I guess I'll drive it over the next few days & evaluate while I'm fixing the Envoy's brakes. Checking it again last night, the 'normal' noise I'm referencing is groaning, but it's not overly loud, and only under greater assist. I'll take that as a positive sign. The only time it ran dry was on the first start after the parts replacement, and then only for about 15-30 sec. And I probably had that groaning, 'pre-parts', TBH. I just don't drive it enough to remember 'normal'. That'll change, soon.

As an aside, this thing pulls hard, even in stock (?) form... between the throttle response, the torque, and the exhaust note, it calls out like a siren's song to step on the go pedal. It's noticeably different from the first 6.0 Sierra I had, which makes me think this one might already be cammed. We'll see, next spring... promise. 🤞

The only remaining things I want to address in the engine bay for now are the knock sensor harness / connector, and maybe a set of plugs / wires. Still need to do some work in the back end, including the spare tire hoist, running the cabling for the backup cam, and (the big one) replacing the rear wheel hubs (yeah, it has them, just like a 4wd truck up front... I can't get away from them) Oh, and the muffler swap, to something quieter.

 

[littleblazer]

Hmm... I guess I'll drive it over the next few days & evaluate while I'm fixing the Envoy's brakes. Checking it again last night, the 'normal' noise I'm referencing is groaning, but it's not overly loud, and only under greater assist. I'll take that as a positive sign. The only time it ran dry was on the first start after the parts replacement, and then only for about 15-30 sec. And I probably had that groaning, 'pre-parts', TBH. I just don't drive it enough to remember 'normal'. That'll change, soon.

As an aside, this thing pulls hard, even in stock (?) form... between the throttle response, the torque, and the exhaust note, it calls out like a siren's song to step on the go pedal. It's noticeably different from the first 6.0 Sierra I had, which makes me think this one might already be cammed. We'll see, next spring... promise. 🤞

The only remaining things I want to address in the engine bay for now are the knock sensor harness / connector, and maybe a set of plugs / wires. Still need to do some work in the back end, including the spare tire hoist, running the cabling for the backup cam, and (the big one) replacing the rear wheel hubs (yeah, it has them, just like a 4wd truck up front... I can't get away from them) Oh, and the muffler swap, to something quieter.

You spelled muffler delete wrong.

 

[Reprise]

What, you're talking open pipes? Lol... that prolly wouldn't be the best thing to listen to for hours on end at highway speeds.

Of course, at 8mpg / 26 gal tank, 'hours on end' is usually <= '3'

 

[littleblazer]

As long as they're past the rear bumper open pipes don't drone or anything surprisingly. You don't have chambers to create harmonics.

The red truck is worse inside with the turbo mufflers than it was straight piped.

 

[Reprise]

No, no... I want quiet... MUFF-le...

Just to put the capper on this thread... Seems like the system worked all of the residual air out, just like Moose surmised would happen. Steering & brakes seem fine again. Yay me.

Of course, life wouldn't be complete without a little more adversity... turns out the Envoy's leak in the brake system is with the hard line in the rear, not the flex hose in the front. And GM's part # for the replacement is the 16ft roll of tubing. Looks like I *am* going to learn how to flare!