Air build up in power steering

[Sergey]

Hello,
first off, this is not diesel specifc question. By asking here since your expert opinion and enormous coverage are highly valuable.

Here is the background. A couple year ago I replaced power steering pump on my 85 F250 with new, from RockAuto. Not the cheapest, not the most expensive. At the same time high pressure hose was replaced with new. In addition low pressure hose was replaced with new, from local auto parts store (sold by foot). Everything was cleaned, new power steering fluid, bled the hydraulic system.
Worked great since then, but until recently....
Noticed that power steering fluid level dropped. No obvious place of leak. But the low pressure hose is wet on its entire length, a bit wetness on power steering reservoir back and side. Seal is dry. A little bit wet on top of frame where steering box is mounted, but box seals are dry.
And the strange observation: every time I open power steering lid (on a warm or hot engine, to check and to top off) there is a pshhhht sound and momentary push. It certainly seems that there is compressed air in power steering reservoir.
Why would it ? Anyone ween something similar, maybe even on another vehicle ?

Thank you
Sergey

 

[rreegg]

Why would it ?

Good question. If the level is dropping and there's wetness I'd assume there's a leak somewhere.
In theory some air could get through the leak, there’s moisture in air, and maybe it heats up and expands and creates some pressure. Even when opening an oil cap there’ll be steam or whatever coming out. Not sure the operating temp of the fluid but it must get at least warm.
No expert here just spitballing.
I’d maybe try to monitor/observe fluid levels with the engine off, with the engine idling (not steering or driving), and with the engine operating (and using steering) and see if it changes under any of the above then go from there.

It’d be great to set up a camera or something to view the area while driving but..

Good luck am sure others on here know wat more than me

 

[The_Josh_Bear]

Maybe we have different PS styles, but for mine it's not a sealed system. There is a bleeder hole on the fill cap.
Sounds to me like your fill cap is not venting and the hot pump/fluid expands the air and so it builds a little pressure. Pressurized fluid will always try to leak out of something, usually the LP hose, but as you know there are many possibilities.

Easiest thing to do: get automotive dye and add to PS fluid after cleaning everything real nice. Then use a black light(UV) to shine all over and it should be easy to find the leak once it starts leaking again.

 

[Sergey]

Maybe we have different PS styles, but for mine it's not a sealed system. There is a bleeder hole on the fill cap.
Sounds to me like your fill cap is not venting and the hot pump/fluid expands the air and so it builds a little pressure. Pressurized fluid will always try to leak out of something, usually the LP hose, but as you know there are many possibilities.

Thank you for the idea.

Your explanation makes sense to me.
I was looking elsewhere but not in power steering reservoir cap ! I guess I'll start with replacing it, and check for that bleed hole in existing one.

 

[Noiseydiesel]

The return line is simply clamped on and is wet the entire length of the hose.
Loose/damaged clamp? Wrong style hose? Is it rated for ATF? Could it be possible the oil is leaking through the hose?

 

[Old Goat]

I buy the wrong type hose is used...maybe

Not power steering, but almost 10 yrs ago I blew the heater Core
late one night. Picked up a new one at Auto Zone, along with the
squeeky blower, and new heater hose from Engine to heater Core.

A few years later I noticed the Hose being wet the full length. Not
dripping but just wet. The coolant was coming through the rubber.
Bought new Gates Hose and never hand another problem.
Was done with Auto Zone.......

So just maybe the same issue with your power steering hose?


Goat

 

[Sergey]

Interesting Goat so the rubber hose can bleed through ... hmmm ... never thought of that. Anyhow, I stopped by at local auto parts store, o'reilys or whatever is now after schucks auto, and check their power steering hose.
Two options : 2 ft precut China made. Look soft and smooth but seems to be kinked inside clear plastic box.
Second option is what they sell by the foot. But it looks different than what bought several years ago. Unknown origin, and hose is stiff by feeling, and its outer surface is like goose skin. It certainly won't kink, but due to its rigid feeling will the clamp squeeze it enough.
Neither hose looks nor feels something I can trust right away.
Will check what is available online, since I need ps reservoir new cap anyway.

 

[Sergey]

A few years later I noticed the Hose being wet the full length. Not
dripping but just wet. The coolant was coming through the rubber.

As second thought, you do describe it almost like what I see. No particular spot, but hose is wet. No drips. Although, given the fan wind, any drips would be blown away momentarily. Wetness won't.
And, only after several years. Exactly.
Will replace the hose, just to eliminate one factor.

 

[Old Goat]

That was a first and only time I ever saw a hose do that.
I haven`t had it do it since.

As far as Power Steering hose, so far haven`t worked on
on that system...yet...so no advice on it, or what hose to use.


Goat

 

[Rdnck84_03]

It is expensive but O'Reilly carries a rubber hose that is rated for atf. I don't remember what it is called but is made by Gates and it looks like fuel hose that is red and much stiffer.

James

 

[IDIBRONCO]

It is expensive but O'Reilly carries a rubber hose that is rated for atf. I don't remember what it is called but is made by Gates and it looks like fuel hose that is red and much stiffer.

James

Years ago, I bought some of that from Auto Zone. I think I used it on my 1984 Mustang.

 

[tbowker]

I don't remember what it is called but is made by Gates

It's called Gates barricade hose. It's a bit more pricey but it's good stuff. I got mine on Amazon.