Hissing noise coming from powersteering or hydroboost

[Enforced_Leo44]

Hi everyone,

I had to swap a power steering line a while back, the one that goes from the hydroboost unit to the steering gearbox, and ever since then my truck made this hissing noise when steering (here's the video for context https://youtube.com/shorts/o1cgesBDYl0?feature=share )

The steering gearbox is a 2wd gearbox (which is leaking a bit out of the front cover and sector shaft seal) because of crossover steering mod and I installed a XJ steering shaft to get rid of the rag joint slop, just wanted to write them here in case any of these 2 mods could play a role in the problem i'm having.

The hissing noise is there only when the powersteering is under load, not when it's resting regardless of the position it's resting in.

Could this be just air in the system or is this a sign that one of the components is about to go out?

 

[WWRD99]

From what I can hear, it does sound like the pump is struggling. Could be air, or there's to much load on it from turning the tires without moving forward at the same time. Not sure the width of tire or type, but some can have pretty good grab sitting on pavement. If you have air in the system the res should show bubbles or even over flow. If you didn't raise the tires off the ground after the repair to get the air out you could have burned up the pump too.

Sent from my SM-S906U using Tapatalk

 

[Enforced_Leo44]

From what I can hear, it does sound like the pump is struggling. Could be air, or there's to much load on it from turning the tires without moving forward at the same time. Not sure the width of tire or type, but some can have pretty good grab sitting on pavement. If you have air in the system the res should show bubbles or even over flow. If you didn't raise the tires off the ground after the repair to get the air out you could have burned up the pump too.

Sent from my SM-S906U using Tapatalk

When I first started hearing this noise, so after the hose replacement, I had 37x12.5s on, before replacing the hose it didn't make any noise with those same tires. Now I have some 40x13.5s on (which... definitely didn't relieve the pump or the gearbox of any strain).
I did anyway lift the front of the truck off the ground for the bleeding procedure. I'll check for bubbles in the reservoir hoping to find them, if no bubbles/signs of overflow are there, guess I'll have to start ordering a new steering gearbox and a new pump.

 

[WWRD99]

When I first started hearing this noise, so after the hose replacement, I had 37x12.5s on, before replacing the hose it didn't make any noise with those same tires. Now I have some 40x13.5s on (which... definitely didn't relieve the pump or the gearbox of any strain).
I did anyway lift the front of the truck off the ground for the bleeding procedure. I'll check for bubbles in the reservoir hoping to find them, if no bubbles/signs of overflow are there, guess I'll have to start ordering a new steering gearbox and a new pump.

Does it make the noise if you move a little forward while turning? Pumps aren't the highest output stock.

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[Enforced_Leo44]

Does it make the noise if you move a little forward while turning? Pumps aren't the highest output stock.

Sent from my SM-S906U using Tapatalk

Yes, a bit less but yes, it's still there. Left or right makes no difference
I'd say it's proportional to how much stress the system is under

 

[WWRD99]

Yes, a bit less but yes, it's still there. Left or right makes no difference
I'd say it's proportional to how much stress the system is under

Tough call with tires that big. Pump could've been on the way out then a touch of air from the new line pushed it over the edge. Possibly try some good hydraulic fluid change?

Sent from my SM-S906U using Tapatalk

 

[Enforced_Leo44]

Tough call with tires that big. Pump could've been on the way out then a touch of air from the new line pushed it over the edge. Possibly try some good hydraulic fluid change?

Sent from my SM-S906U using Tapatalk

I've read and been told to use ATF fluid, specifically Dex 3. Previous owner said he always refilled with Dex 3
Is it ok to use ATF or should I switch to PS fluid?

 

[WWRD99]

I use dexron 3 a bunch too...there is specific power steering fluid that is thicker that might take more abuse for the bigger tires. But if it's making noise now it might not do anything.

 

[Enforced_Leo44]

I use dexron 3 a bunch too...there is specific power steering fluid that is thicker that might take more abuse for the bigger tires. But if it's making noise now it might not do anything.

Got it.
As stated, I'll check for bubbles in hope of finding them.

If I remember correctly, I just have to lift the front, steer lock-to-lock and pump the brakes a couple of times, and even with the engine off that should move some bubbles to the reservoir IF there's air present, right?

 

[WWRD99]

Got it.
As stated, I'll check for bubbles in hope of finding them.

If I remember correctly, I just have to lift the front, steer lock-to-lock and pump the brakes a couple of times, and even with the engine off that should move some bubbles to the reservoir IF there's air present, right?

Yes that will work good getting the air out

Sent from my SM-S906U using Tapatalk

 

[Enforced_Leo44]

Also, forgot to add that the steering itself feels fine, as in it’s not hard or touchy, there’s some play of course but nothing to write home about.