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About alvocado

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  1. 2011 GMC Yukon: I've replaced my PS pump twice in the past month with new AC Delco, OEM units and the second pump is still noisy. I've flushed the system completely, used Valvoline PS fluid, replaced the pressure and return lines, used new seals on the lines at the reservoir and steering rack, and bled the system at least 5 times. The pump still whines especially when turning. There is no sign of air in the reservoir (bubbles or foaming) nor any sign of fluid leaking. Are these made in China pumps that unreliable or am I missing something? There could be air pulling into the system at one of the hose connections without a visible fluid leak but I would think that would result in air bubbles in the fluid. Any thoughts are appreciated. I dread the idea of pulling this a third time and dealing with the inconvenient Rockauto return process.
  2. Since the GM part is $7 for one o-ring, I found a suitable substitute from a Harbor Freight HNBR o-ring assortment set for those who need to replace this seal. Here are the specs: GM part: 7.65mm ID x 1.63mm thickness (0.301 in x 0.0642 in) Standard HNBR #A011: 5/16" ID x 1/6" thick (0.3125 in x .0625 in) You can buy the 205 piece set for the cost of the single GM part.
  3. I removed the pads, cleaned the caliper bracket and shims, lubed the shim surface and pad ears and reinstalled. No change.
  4. The slide pins looked identical to me and made no noise when manually moving the caliper with the piston compressed to allow some movement while mounted. I've removed, cleaned and lubricated the pins twice with no change. The sound appears to be coming from the caliper body when I listen with my ear next to the system. In my experience, failure to clean and lubricate the pad mounting surface on the caliper bracket would only cause squeal due to pad vibration. The brakes were bled last summer but I may bleed this corner to make sure fluid is flowing through the caliper properly. There are no unusual marks on the rotor or pulling due to uneven braking.
  5. My driver's side rear brake on my '11 Yukon is making a creaky noise when activated and I'm out of ideas on the cause. I cleaned and lubricated both guide pins but it didn't help. Both pins slide as expected and don't make noise when moved manually. I pulled the caliper again today and inspected and cleaned the piston. The piston seals look fine with no leaking, bulges, etc. The piston surface cleaned up with brake cleaner and depressed easily prior to removal with a c-clamp. There aren't many moving parts so I'm out of ideas other than the entire caliper may be bad. Here's a video with the tire off, truck on stands and my son depressing the pedal fully to the floor. It sounds like an old bed spring. Any ideas are appreciated.
  6. I replaced the P/S pump and hoses on my '11 Yukon and the Gates pressure hose did not come with a new oring for connecting at the back of the pump. I reluctantly reused the OEM oring but it is not sealing. Does anyone know the spec for this oring, size and material or if it's possible to source just the o-ring? Searching has not turned up any information. I have an NBR o-ring assortment if the material is compatible with P/S fluid.
  7. To clarify, the "creaking" noise from the original post is not from the pads or rotors as it happens while parked and depressing the brake pedal. Brake squeal when applying the brakes to stop or slow down is a result of the pads vibrating which does not necessarily indicate the brakes aren't working correctly. If your brakes are in good working order and you get squealing when applying, it's either due to the material (harder pad composites), product design (no or inadequate backing material on the pads), or shims (caliper surface not properly cleaned and lubricated when installed).
  8. All heater hoses and connections are dry. I did notice that the engine mount directly above the stained area on the steering rack also has the same dried residue so any fluid leaking appears to be coming from directly above the mount. I can't see anything above the mount due to the exhaust manifold and shields.
  9. I did check the A/C drain and it's very unlikely to be the cause. The tube is located far enough away and I couldn't see a way for condensate to work it's way over to this area of the steering rack. Another thought after posting is the heater core or heater lines since those are at the firewall. I'll inspect those today.
  10. 2011 GMC Yukon 5.3L, 135k miles. I have a mysterious, intermittent leak that I can't trace and am looking for some help. I first noticed some dried, brownish dust on the garage floor which looked like a dried fluid. It was powdery and didn't leave a residue. This happened twice over the summer. While changing the oil, I noticed similar colored residue on the steering rack and adjacent transmission cooler lines (see pic.) The picture shows the rack near the boot on the passenger side of the truck. I can't see any fluid or residue above the rack. I checked the head gasket and the front half is dry; I could only see the front half due to the exhaust manifold blocking the view from above and I couldn't get a mirror on the back portion. Some other notes: I'm not losing any coolant. The level is constant in the reservoir I've had a strange popping noise at cruising speed for the past year that has been elusive. It doesn't vary with RPM and is random. It sound like something flapping under the track. It may be unrelated but I'm noting in the event it's exhaust related or something that could happen with a manifold or head gasket issue. The truck seems to be a bit louder than usual at highway speeds under hard acceleration Any help is appreciated.
  11. AC Delco makes a clutch kit. Search for part number here: https://parts-catalog.acdelco.com/catalog/catalog_search.php
  12. Try tpmsdirect.com. I bought a set in the spring for a 2008 Audi A6 and they had OEM supplier sensors at a great price. Here's a link to the '07 GMC Sierra options including a set of four for $105. The owner was great at answering questions over the phone and confirming fitment. https://www.tpmsdirect.com/GMC_Sierra_TPMS_s/509.htm
  13. The brakes on fullsize GM trucks last a long time which is great with one downside: you don't regularly service the components since you aren't changing out pads very often. Here's a picture of my rear caliper guide pins showing the factory lube is mostly gone and what remains is hard and worthless. I pulled these today to clean and lube with correct caliper guide pin grease (used Permatex green brake lube). When swapping my front setup to a PowerStop z36 kit yesterday, one of the front guide pins was rusted near the head and had no grease remaining. That was likely an issue with the guide pin boot letting in moisture combined with no lube so all were replaced with the new boots from the PowerStop kit. It takes about 30 mins to maintain the guide pins per axle and inspect the boots and I recommend doing it at least every couple of years if you aren't changing brakes. This resolved my rear squeak issue.
  14. People underestimate the importance of the right tires for the usage situation. Winter tires aren't just for snow. They are made with rubber compounds that remain more pliable at cold temps. All seasons do a reasonable job across a range but don't expect them to perform well in anything more than a dusting or extremely cold temps. Wider tires also perform worse than narrower tires in snow. I put winter tires on an AWD Audi and it drives like a tank in heavy snow and significantly out performs my 4WD Yukon with all season tires.
  15. Oil pressure sensor locations from Alldata for my 2011 Yukon, 5.3L. Both are at the rear of the engine and the filter screen sits inside the hole under the pressure sensor. For those running frequent oil changes, you may consider sending off your oil for analysis (Blackstone Labs, etc.). Other than an 800 mile break-in change, I run 15,000 mile OCI with Mobil1 EP and Mobil1 filters. I've never had an issue, don't consume any oil between changes, and the oil tests fine. Current odo is 124,000 miles. The only repair in 8 years was a warranty seal replacement on my midshaft differential.
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