power steering pump whine issues

AuroraGirl · Jun 14, 2024

AuroraGirl said:
HOw long was your brake pedal applied?

GOing down a grade, you should NOT have had your foot applied to it

also did you have a cooler on for this occurance? humidity and the fact you were at 2000ft starting out will greatly affect the temperature of the fluids abilitys

Cooling is less ,heat generation is the same (same enough to not be relevant) and humidity increases means much less transfer ability. SOunds more like an air bleed situation, brake fluid possibly even. automate bleed of your brakes after flushing that brake fluid, and make sure all pads/rotors are wearing right, and that all drum shoes are adjusted to be proper and the springs are pulling them off when not applied. ANY increase in travel for brake actuation is a HUGE increase in pedal application before any meaningful braking occurs

dragging can cause heat buildup, which can make hoses hot and spongy, which makes pedal pressing less direct, which makes pump have to work harder to assist your braking and steering esp at the same time. not saying it should be worse than your old setup tho. is your old hydroboost stock, and this is an aftermarket hydroboost but not like a gmt800 retrofit right

kylenautique · Jun 14, 2024

AuroraGirl said:
also did you have a cooler on for this occurance? humidity and the fact you were at 2000ft starting out will greatly affect the temperature of the fluids abilitys

Cooling is less ,heat generation is the same (same enough to not be relevant) and humidity increases means much less transfer ability. SOunds more like an air bleed situation, brake fluid possibly even. automate bleed of your brakes after flushing that brake fluid, and make sure all pads/rotors are wearing right, and that all drum shoes are adjusted to be proper and the springs are pulling them off when not applied. ANY increase in travel for brake actuation is a HUGE increase in pedal application before any meaningful braking occurs

dragging can cause heat buildup, which can make hoses hot and spongy, which makes pedal pressing less direct, which makes pump have to work harder to assist your braking and steering esp at the same time. not saying it should be worse than your old setup tho. is your old hydroboost stock, and this is an aftermarket hydroboost but not like a gmt800 retrofit right

I'm using stock GMT400 components for the brake system. The hydroboost is for a 1998 k2500/3500 with the matching master cylinder. I have the 1 ton front calipers too. The stock low drag are not compatible with the hydroboost MC. The only thing GMT800 that is on my truck is the rear brakes. I have rear disc brakes off a 2001 Silverado 1500 using the aftermarket aluminum spacers so I can retrofit the 10 bolt backing plate directly to my 14 bolt heavy half ton rear axle. Its a very slick setup. All stock components and an excellent parking brake. The only thing that has changed is now instead of a T fitting for the Hydroboost return, I'm using a pump with two return inputs. Idk if that's the smoking gun or not. I only replaced the power steering pump a few months ago because I rebuilt the engine, and the pump felt a little tired when turning at low speeds in a parking lot. The system was working great. Using straight ATF.

I'm wondering the fluid is the issue. O'reillys power steering fluid is rated to 260deg, where as ATF is rated to 400deg. The royal purple PS fluid is also rated to 400deg. I have no idea what we are running at temp wise with hard breaking and turning, but perhaps I'm flirting wit hthat 260 deg level? It would make sense that the ATF would work better. But, the ATF may have been the reason I've been going through pumps in the first place? I couldnt tell you what fluid was in my OEM pump. Perhaps it was PS fluid? I do know that I filled it with Dex3 when I installed the hydroboost. So with the video I posted, I may have had this PS/Dex3 blend for a while? My pump still whines when its cold, which is not supposed to happen, so regardless, I'm going to replace it within the year. But, its a good candidate to mess with fluid. I'm going to flush it with royal purple and give that a try.
https://www.oreillyauto.com/detail/...-ez-power-steering-fluid-12-ounce/ryp9/maxpsf

GoToGuy · Jun 14, 2024

Brake temperature is accumulative. Even lightly braking downhill, pad temperature will continue to rise. Your 5000 lb vehicle on level surface taking x amount of brake power to stop. When going downhill slope angle x vehicle wt = can be stopping a six , seven thousand pound vehicle or more. With a proportional increase in brake temp. A very good reason for clean brake fluid, water entrapped in brake , high brake temps, the water would boil.
Foaming , as long as the level is always above the pump intake, is unlikely. Except in very high RPM uses, racing , endurance, then more likely a cavitation problem. A pressure demand system, there is no suction side. A pressure side pump output, and return side reduced pressure.
The foaming issue, without facts , or testing very unlikely.
You can compare fluids, not the tooling they operate in. A very basic pump on one side, the other a highly complex turbine with friction materials , solenoids, hydraulic functions, gear and bearing lubrication. They are not the same.
A pump that make more noise under load could be a weak pump. Is the pump off a topkick or Kodiak a better choice or are they the same as a 3500 series?

AuroraGirl · Jun 16, 2024

kylenautique said:
I'm using stock GMT400 components for the brake system. The hydroboost is for a 1998 k2500/3500 with the matching master cylinder. I have the 1 ton front calipers too. The stock low drag are not compatible with the hydroboost MC. The only thing GMT800 that is on my truck is the rear brakes. I have rear disc brakes off a 2001 Silverado 1500 using the aftermarket aluminum spacers so I can retrofit the 10 bolt backing plate directly to my 14 bolt heavy half ton rear axle. Its a very slick setup. All stock components and an excellent parking brake. The only thing that has changed is now instead of a T fitting for the Hydroboost return, I'm using a pump with two return inputs. Idk if that's the smoking gun or not. I only replaced the power steering pump a few months ago because I rebuilt the engine, and the pump felt a little tired when turning at low speeds in a parking lot. The system was working great. Using straight ATF.

I'm wondering the fluid is the issue. O'reillys power steering fluid is rated to 260deg, where as ATF is rated to 400deg. The royal purple PS fluid is also rated to 400deg. I have no idea what we are running at temp wise with hard breaking and turning, but perhaps I'm flirting wit hthat 260 deg level? It would make sense that the ATF would work better. But, the ATF may have been the reason I've been going through pumps in the first place? I couldnt tell you what fluid was in my OEM pump. Perhaps it was PS fluid? I do know that I filled it with Dex3 when I installed the hydroboost. So with the video I posted, I may have had this PS/Dex3 blend for a while? My pump still whines when its cold, which is not supposed to happen, so regardless, I'm going to replace it within the year. But, its a good candidate to mess with fluid. I'm going to flush it with royal purple and give that a try.
https://www.oreillyauto.com/detail/...-ez-power-steering-fluid-12-ounce/ryp9/maxpsf

which of the two return ports is your steering hooked up to vs the hydroboost, and i forgot if you mentioned, but do you have a vacuum bleeder? And what is the difference between gmt400 rear brakes vs gmt800 rear brakes? Like,m would the gmt400 brakes still be disc or would they be large drums?

kylenautique · Jun 17, 2024

AuroraGirl said:
which of the two return ports is your steering hooked up to vs the hydroboost, and i forgot if you mentioned, but do you have a vacuum bleeder? And what is the difference between gmt400 rear brakes vs gmt800 rear brakes? Like,m would the gmt400 brakes still be disc or would they be large drums?

On the hydroboost system, for the return ports, the hydroboost is going into the top port and the steering goes into the bottom. Originally, I had a T fitting for the hydroboost, because the original pump didn't have the extra return port. For my brakes, the rear brakes were originally drums that the stock 14 bolt heavy half ton axle came with. I believe they were 11 or 12" drums? Its a fairly simple install to upgrade to stock GMT800 rear disc brakes. Braking performance wise, its not a huge difference between the drums and the disc. Properly adjusted, the drums probably bite a little harder initially, but will fade due to heat quicker. The disc brakes feel smoother, and just don't fade as quickly. Also, they don't lock up as easy too which is a plus. It feels more refined. I used both rear brake versions with the hydroboost setup. The Hydroboost is more worth the investment over rear disc brakes if someone is looking for better brakes on these half ton trucks.

My ABS is also deleted (the unit failed) which makes the rear disc brakes setup better. The fronts are plumbed/teed together, and the rear brake pressure is controlled by a Wilwood proportioning valve. With the rear disc brakes, I leave the valve at full power, which is 1200psi

I've been running hydroboost on this truck since 2019, deleted the ABS in 2020, and converted it to disc brakes in 2021. I've put thousands and thousands of miles on this truck. Its my daily driver and family hauler. This pump issue is a new problem I've never had before.

AuroraGirl · Jun 17, 2024

You run full pressure to your rear disc? On single piston calipers? Are your fronts dual piston or single?

Also you should get the drag reduction clips for the rear pads it will help with pad wear esp on the inboard pad

When it comes to your hydro unit, did you do any pushrod adjustments

AuroraGirl · Jun 17, 2024

Just for fun you should swap your return ports and see if you have any noticeable difference in behavior.

I don’t think it will but it’s a good learning experience for us all

kylenautique · Jun 17, 2024

AuroraGirl said:
You run full pressure to your rear disc? On single piston calipers? Are your fronts dual piston or single?

Also you should get the drag reduction clips for the rear pads it will help with pad wear esp on the inboard pad

When it comes to your hydro unit, did you do any pushrod adjustments

The Wilwood proportioning valve on the rear brakes is set to max pressure but is limited to 1200psi, which is perfect for disc brakes, and with larger tires, I could probably use a different valve allowing more pressure. The rear brakes stop fantastic and never lock up. When I had the drum brakes, I kept the valve around 600psi. https://www.wilwood.com/MasterCylinders/MasterCylinderProd?itemno=260-10922

Currently, I'm using the stock GMT400 single piston rear calipers, but I plan to upgrade to the GMT800 Escalade/Denali two piston calipers soon-ish. When I did the swap, I purchased a complete 10 bolt rear end for $150 from a 2001 Silverado 1500. I took the backing plates, calipers, brakes lines, rotors and parking cables and swapped all the parts directly to my truck using the Cunningham Machine spacer. https://cunninghammachine.com/gm-14-bolt-60mm-spacer-for-nbs-rear-brake-conversion I sold the axle a few weeks later for $150. Win win! All I had to do was make a few brackets to hold the brake lines by the calipers, a mounting bracket for the parking brake cables, and that was about it. Took me a full Saturday to do the swap. I was driving it by the eveining.

AuroraGirl · Jun 19, 2024

kylenautique said:
The Wilwood proportioning valve on the rear brakes is set to max pressure but is limited to 1200psi, which is perfect for disc brakes, and with larger tires, I could probably use a different valve allowing more pressure. The rear brakes stop fantastic and never lock up. When I had the drum brakes, I kept the valve around 600psi. https://www.wilwood.com/MasterCylinders/MasterCylinderProd?itemno=260-10922

Currently, I'm using the stock GMT400 single piston rear calipers, but I plan to upgrade to the GMT800 Escalade/Denali two piston calipers soon-ish. When I did the swap, I purchased a complete 10 bolt rear end for $150 from a 2001 Silverado 1500. I took the backing plates, calipers, brakes lines, rotors and parking cables and swapped all the parts directly to my truck using the Cunningham Machine spacer. https://cunninghammachine.com/gm-14-bolt-60mm-spacer-for-nbs-rear-brake-conversion I sold the axle a few weeks later for $150. Win win! All I had to do was make a few brackets to hold the brake lines by the calipers, a mounting bracket for the parking brake cables, and that was about it. Took me a full Saturday to do the swap. I was driving it by the eveining.

So I did some research, evidently the gmt400 quick take up master cylinder is designed to be used with rear drum and as such incorporates the function of a residual pressure valve into it. Have you considered using a Gmt800 master cylinder (from the rear disc ones, not the later rear drum ones)

THe pedal feel may improve and it may also help your situation. I guess I could see maybe a sticky piston is somehow contributing to your whine but I doubt it. But consider this suggestion as an offshoot of your whine issue and just based on my preliminary searching.

And did you mean single piston rear gmt800 rear calipers, not 400?
I didnt know the escalade or denali got two piston rears. Is this only in the half tons or does it apply to the 3/4 tons?
Cables worked directly with your parking brake pedal and routed nicely? Nice.

Do you by chance have a dial indicator?

HotWheelsBurban · Jun 19, 2024

AuroraGirl said:
So I did some research, evidently the gmt400 quick take up master cylinder is designed to be used with rear drum and as such incorporates the function of a residual pressure valve into it. Have you considered using a Gmt800 master cylinder (from the rear disc ones, not the later rear drum ones)

THe pedal feel may improve and it may also help your situation. I guess I could see maybe a sticky piston is somehow contributing to your whine but I doubt it. But consider this suggestion as an offshoot of your whine issue and just based on my preliminary searching.

And did you mean single piston rear gmt800 rear calipers, not 400?
I didnt know the escalade or denali got two piston rears. Is this only in the half tons or does it apply to the 3/4 tons?
Cables worked directly with your parking brake pedal and routed nicely? Nice.

Do you by chance have a dial indicator?

My only experience with GMT 800 rear disc brakes is on the '06 Yukon XL Denali that Dad had, and it had two piston rear calipers. They seemed to be aluminum, and set in a steel bracket/frame. The caliper pins go into a sleeve; to tighten up the bolts you need to hold the sleeves with wrench. IIRC it's a 5/8" or 16mm, there are flats on the sleeve to facilitate this.

power steering pump whine issues

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