PS fluid bleeding does not work!

[kilou]

Thanks for the reply. No I have not done a flush of the rack prior to refitting. I have done a flush of the complete system only 15'000km ago so I don't think it was really necessary. I think I've gone from lock to lock correctly but I'll still try again. However what bothers me is that I cannot see any air bubble in the fluid reservoir. Normaly if there is still trapped air, I should see foam but I see nothing.

To bleed the system I've turned the steering wheel from lock to lock with the wheels on the floor. Now I'm a little afraid to bleed the car for too long with the vehicle on the floor because it places too much strain on the steering components. Do I really need to have the vehicle resting on its wheel to bleed the system or should I put the front end on axle stands to remove excessive strain on the steering rack while bleeding?

 

[Kestas]

If you're worried about the excessive strain and scrubbing I would just take it to a parking lot and turn from lock-to-lock while creeping along.

The flush I mentioned is recommended for new racks or if the work was very intrusive. I get the impression you did only minor work. So you should be okay without a flush.

Perhaps you're experiencing the same thing I did, in which case you'll have to be patient and let the air work itself out.

 

[kilou]

Hi,

I recently had to do some work on the steering rack and I had to take it out of the car. Now I've put everything back together, filled the PS system with new fluid and bleeded it. Now the power steering works OK but the pump makes a hissing noise when the steering is turned. I know this can come from air still trapped in the fluid but I've spent a few hours to bleed the system without any change in the noise! The fluid level in the reservoir is OK and does not drop. Moreover I have absolutely no foam forming on top of the fluid reservoir so I assume the fluid is correctly bled no?

I doubt the pump would have gone bad by coincidence just after having done the job on the PS system. Before that there was no noise coming from the pump or PS lines.

The new fluid I used is excatly the same one that was in before (Valvoline ATF DexronIID).

If there is still air in the lines, why does the bleeding not remove it efficiently? Is there anything else to do? The car has been driven now for one week without PS problem at all but I don't want the pump to fail because of trapped air.

Thanks

 

[Kestas]

First, did you flush the rack with a quart or two before buttoning everything back up? It is recommended to do this by rack rebuilders.

Did you go through the full range of steering motion, lock-to-lock? This moves the fluid through what are otherwise dead spots in the system.

If it helps any, I still had air in the PS system of an '01 Sable after doing a fluid exchange (the one where you disconnect the return line). The air worked itself out after a couple of weeks. I still don't know why air persisted in the system for so long.

 

[White 03]

I can't imagine putting the car on stands while turning wheels back and forth could hurt anything; and it might make the bubble come out.

Another thing is I have read (but not seen myself) that Ford uses vacume to bleed the power steering after working on them. I don't exactly know how it is accomplished but maybe a mighty vac could be adapted to your system.

It is just a though and I have never done it.

 

[1maniac]

IS there something stuck in the system? Debris in the fluid partially blocking the pump intake?

 

[kilou]

quote:

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Originally posted by 1maniac:
IS there something stuck in the system? Debris in the fluid partially blocking the pump intake?

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I don't think so because when I disconnected the fluid lines, I put some tape around each ends to prevent any dirt to come in. Moreover if something was stuck in the system, the steering should feel strange or maybe I may not have any PS at all, but everything works OK only the hissing sound bothers me.

Of course turning the wheel from lock to lock witzh the car on axle stands will not hurt anything but I've heard it's not efficient at removing the air bubbles because the pump does not have to work as hard as when the wheels are on the ground. It's true that the hissing noise is much more important when the bleeding is done with the vehicle on the floor than when it's on axle stands.

I'll still try to make some lock-to-lock steering to see if this noise goes away but....

Thanks

 

[TheTanSedan]

PS pumps generally have an inlet filter screen worth checking.

As to flushing I follow directions given me by a major rebuilder and start by putting the front end up on jackstands. After fluid fill, go slowly lock-to-lock, pausing momentarily at each stop. Start and stop engine often to check fluid level.

 

[Silk]

With the wheels off the ground and the engine OFF,turn the ROAD WHEELS ,NOT the steering wheel slowly lock to lock a doz times,seldom they don't bleed this way.

 

[dkcase]

quote:

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Originally posted by Silk:
With the wheels off the ground and the engine OFF,turn the ROAD WHEELS ,NOT the steering wheel slowly lock to lock a doz times,seldom they don't bleed this way.

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I posted another thread where I related that I had turned my steering lock-to-lock from the steering wheel, and it caused the fluid to oveflow at the pump reservoir.

Confused me, because i know turning lock to lock is recommended to remove air. In my case though it caused it to admit air, which I drove around with to allow to escape.

So, is the secret to turn the steering by pulling on the road wheels ? Pushes against the reverse side of the gears, or something ? Mine was a Ranger pickup, rack and pinion.

 

[Fuelrod]

Don't ignore TanSedan's advise about the filter screen inside the reservoir tank. If partially blocked, the pump will moan....