tomazb

Dear all,

I am new at the Forum. As a big fan of 911 for years, I decided to learn
more about daily "specifics" of our cars and not pay full Euro to the mechanics.
My present 911 is 997 Carrera S 2006.
I have no problems with the car and I am using it on weekends.
One thing appeared recently, when temperature dropped below 10 C.
Engine starts on "first key" no matter of temperature, but the steering
wheel stays "hard" - not powered for a couple of minutes. Then first it
moves to the Left side and after that on the Right direction. After once the
power is on, the steering works as usually. Even if you stop the car in the
middle of the day it works normally till you park it through the night.
We changed the belt on the steering pump already as firs step. The pump
works normal and the oil is not leaking...
As I am the second owner - the mechanic noticed on the steering "system?"
a label 1213? - it seems that the part was replaced or repaired, already.
Some 911 friends claim it should be a problem with oil valve or sensor, that
does not let the oil come into the steering chamber?
I would be happy if someone can share this experience whit me, as I am not
happy to wait minutes to leave for the ride....
Thank you for all your INFOS.....

T. Belinger

Macster

Rare.

About all I can think of is the fluid is wrong or has been contaminated. (Some years ago my Dad took his Chevy Suburban into a quicky service joint and unbeknownst to him some "tech" added oil to the brake fluid reservoir. Everything was ok for some miles until the brakes stopped working right. When the problem was found the entire braking system had to be replaced.)

If not the fluid, and I really don't think it is fluid related -- then the problem is probably with the control valve that as the driver turns the wheel admits power steering fluid under pressure to one side or the other of the rack which then provides the "power" assist as the driver turns the wheel further.

This control valve is designed that if the wheel is kept centered high pressure fluid is routed to both sides of the rack piston. When the wheel is turned one side's flow is cut off to one side of the piston (and a valve is opened that lets the fluid escape from that side as the piston moves in that direction) and the other side continues to receive high pressure fluid.

It kind of reads like the valve is not working right (to state the obvious) and for some reason the high pressure fluid is not cut off to the opposite side to which the wheel is being turned.

Regardless this valve is (probably) not a field serviceable item and that means that if this is where the problem resides the entire rack will have to be replaced.

However, there may be a shop around that rebuilds this rack and could possibly salvage the rack from your car for less than it would cost to replace it.

But before you throw a new rack at the symptom, or remove the rack to have it rebuilt -- if that is an option available to you -- you would really like to get the cause nailed down.

Could the problem reside in a power steering pump that for some reason doesn't generate the necessary hydraulic pressure from cold? Could there be a sticking open/leaking high pressure relief valve? Could the belt tension be weak enough -- at least at colder temperatures -- that the pump is not being turned at sufficient RPMs to generate the necessary high fluid pressure?

Only a trained/experienced tech I think can answer these questions.

BIG smoke

How old is the fluid? I have had power steering issues go away with a good flush, and change to clean fresh fluid.
Do follow up with your results, Newbie. And Welcome.

tomazb

Thank you for your quick replies. I agree it is rare.
If I would be a mechanic my first thing would
be to change a fluid. I will demand this. As I read
Your opinion I think it really has something to do with fluid
pressure in the system, as sistem works OK after warming up.

Keep you updated.
TB

Wayne Smith

Control valves can stick until they warm up. Macster had some interesting insights on this. Changing the fluid could assist the valves. Please do let us know the outcome.

Macster

You can change the fluid. It is a reasonable action without clear indication of what could possibly be wrong.

While the system is not intended to have its fluid changed, this doesn't mean that with a bit of work you can't change the fluid.

One way is to remove the return line at the pump and remove the belt and spin the pump in the right direction and hand pump fresh fluid through the system and out the return line. You can remove some of the old fluid before you start -- use a turkey baster -- to reduce the amount of fresh fluid you will need.

You have to be sure you catch this fluid as Pentosin is not good stuff to splash around.

You have to be sure you do not let the pump reservoir get too low that you introduce air into the system. (As there is no flush procedure there is likewise no bleed procedure.)

This technique will use a "considerable" amount of new fluid. Have enough on hand.

This technique I believe will leave some old fluid in the rack.

Another technique leaves the return line connected. You remove some of the oil fluid with a turkey baster. Then add fresh fluid and turn the pump until the contents of the reservoir is old fluid again, then remove as much of this as you can and refill with fresh fluid and repeat until you see fresh fluid coming back in the tank.

If you want to be more through after you start getting fresh fluid out the return line connect the return line and top up the power steering fluid reservoir and put the serpentine belt back on and start the engine. Check for leaks and noises and and with the engine off check the fluid level again and if everything is ok restart the engine and let the engine idle while you turn the wheel lock to lock then back to center.

Shut off the engine and when things are cool enough do the flush again. Tthis time you'll remove the fresh fluid you just added mixed with the remaining old fluid. But the result is the system including the rack now has about as fresh of fluid in it as you can get without an extraordinary amount of additional work.

Or if you prefer after the initial flush button everything up and check the fluid and then road test the car and see if the steering behavior is ok on the road and at other times then let the car sit and repeat the conditions under which the initial complaint arose and see if things are better. It may be if the symptom is fluid related that just the 1st flush with fresh fluid is sufficient.

If the symptom is gone then it was the fluid.

If the symptom is still present then you can redo the flush but frankly I think it would be a waste of good fluid. But OTOH I'd sacrifice fluid to avoid the possibility of unnecessarily replacing any of the power steering hardware.

Be sure you dispose of the old fluid properly. It is not nice fluid so you can't or shouldn't just dump it down a storm drain someplace or flush it down the toilet. Maybe where you buy the fluid can take back the old fluid.

tomazb

Thank you for very detailed information. I will keep you informed what was the issue, when solved.

TB