Power steering fluid coming out the cap

[Paul G]

I get power steering fluid come out of the cap and run down the side of the pump. It is annoying to say the least. So I tried a new cap first thing and that didn't help. Replaced the pump with a reman pump from Napa less than a year ago, no help there. I read that the fluid can boil in the pump. So today I plumbed in a fluid cooler and went for a drive, fluid still came out the cap. With the engine hot and running I removed the cap and looked inside the pump, the fluid looked like it was boiling. Bubbles all inside the reservoir.

Is there better, high temp, fluid to use rather than off the shelf "power steering fluid"? I wonder if ATF+4 would be better? It is synthetic and designed for higher temp tranny duty. Come to think of it what fluid was used in the power steering back in the day? I used to use regular Dexron tranny fluid years ago, IIRC.

Or could it be a POS cap?     

[chargerbr549]

I usually run just regular Napa power steering fluid in mine, back in the day most Gm and Chrysler vehicles used power steering fluid in them but the most of the Fords used transmission fluid and it seemed the farmers used whatever hydraulic fluid they had laying around. Lol

I think the only time I ever had fluid pushing out the cap is when i overfilled the reservoir but there maybe something else going on there.

Kevin

[A383Wing]

Paul, I doubt it's yer cap....and I use just regular PS fluid or ATF in all mine....

[cudaken]

Paul, does the pump feel real hot? I am not sure what temp the fluid boils at, but sure it is well over 300 degrees. Have the pump temp read with a thermal heat gun.

I had to replaces my pump and it did stop the overflow. If your replacement pump is working right (I leaned a long time ago just because it is new does not mean it cannot be bad) then I would look for leaks on the return side of the pump and box. Could be sucking air into the fluid on the return line.

Just did a Google and found this.

Pinched Lines

    The pressure side line of a power-steering pump can sometimes become pinched. This causes pressure to back up into the reservoir and gives the appearance of boiling.

Here is a link.

http://www.ehow.com/facts_5644963_causes-power-steering-fluid-boil_.html

Good luck, and remember just because it cannot be the problem does not mean it is not the problem! Boy I leaned that the hard way! 

Ken

   

[70 sublime]

I wonder if you have an od pulley set up ??
Could the pump be geared up too much by turning too fast ?
Too big of pulley on the crank compared to the one on the pump ?

[rt green]

I wonder if the pressure relief valve is sticking.

[Cooter]

Bubbles doesn't ness. Mean boiling....I gotta feeling the fluid it Getting aireated somehow.
I've seen valving do this as well as pump.I'd be trying atf fluid as it has anti foaming agents...

[Paul G]

I'd be trying atf fluid as it has anti foaming agents...

That is where I am leaning. I found an O-ring in my pile of parts that fit under the gasket in the cap. The cap goes on much more snugly now. It was kind of loose before. 

[ws23rt]

I'm with cooter---the oil is getting air from somewhere and mixing into what you are seeing.
If the level in the pump is high enough to prevent sucking air it must be coming from the steering gear or the return line.

[rt green]

you can bleed out air in a power steering pump 3 ways. 1 let it sit overnight and hope for the best. 2 Jack the front end up so the wheels are off the ground. engine off. turn the st wheel lock to lock at least 13 times[factory Gm procedure-works]. 3 rubber stopper in top of pump with a hole drilled in it with a hose stuffed in the middle. connect to a vacuum pump. hand held or otherwise. create vacuum.  personally I use the number 2 method.

[A383Wing]

I have never had to "bleed" a Mopar pump as stated above....Fords, yes, Mopar, no

[fy469rtse]

We had a make and model of Holden motor car here in Australia that GM could not solve , some one  in a dealership came up with an insert which prevented the aeration,  and that became a factory item, very course stainless like those old type kitchen pan scrubbers inserted in the reservoir area, don't know if it would work , but I know if you took it out, the effects would be as you stated,

[Paul G]

you can bleed out air in a power steering pump 3 ways. 1 let it sit overnight and hope for the best. 2 Jack the front end up so the wheels are off the ground. engine off. turn the st wheel lock to lock at least 13 times[factory Gm procedure-works]. 3 rubber stopper in top of pump with a hole drilled in it with a hose stuffed in the middle. connect to a vacuum pump. hand held or otherwise. create vacuum.  personally I use the number 2 method.

Going to try #2 this evening. Cant hurt. The return hoses are brand new, clamps are tight, and no leaks. I cant see how they could be sucking in air. Any better way to check other than looking for leaks?