Hi guys,
first of all I just want to say how much I appreciate this forum and thank you for all the great info!

I know there are a lot of power steering threads but honestly I think I read all of them and nothing solved my problem.
The car is a 2003 M/T 350Z.

The power steering was ok over the years, I didn't have any issues until now when it went from no problem to completley stiff in 2 days.

What I did:
- The power steering pump was removed and rebuilt using Gates rebuild kit. Everything was cleaned, all the seales changed and lubricated and all the bolts torqued after service manual. (images attached of the opened pump)
- The power steering fluid was flushed 2 times as well as I could and changed to Motul ATF VI which is compatible. I didn't notice any debris when flushing.
- The belt was changed to a new Gates belt and tightened properly (actually both belts were changed).
- I bleeded the system at least 10-12 times in every way I could find (lock to lock with wheels down, with the front suspended, with the engine off, with engine on, using vacuum pump, without vacuum pump, holding in lock positions, not holding in lock positions etc.).
- The fluid is not foamy and there are no bubbles at all in the liquid when doing the bleed procedure or after.
- When leaving the vacuum pump on the reservoir with a vacuum of 18 inHg (0.6 bar) for more then 10 minutes, the vacuum doesn't drop at all.
- The fluid level in the reservoir doesn't drop at all.
- I inspected all the hoses and lines as well as I could to not be bent or to leak and nothing.
- The pump doesn't leak.
- The rack doesn't seem to leak either.
- The reservoir is filled to Cold Max all the time.
- Tyre pressure is ok (OEM sizes).
- Car is not lowered.
- Belt is not slipping.
- Rpm doesn't drop when turning the wheel (power steering pressure sensor was changed 1-2 years ago).
- There are no errors that I could read.
- Pulleys seem to be alined.
- At idle there are no sounds.

One thing I did that shouldn't affect this, I removed the idler pulley (used a spacer for the power steering pump mounting braket and a shorter 1 inch belt).

Everything with the car works great except the power steering which is as stiff as it could be.

Different observations:
- The pump whines moderatley but only when turning the wheel at high rpms.
- If the engine is off and the car is lifted, when you move the wheel from lock to lock you can hear a loud squishing sound from the rack (I even stayed under the car to be sure it's the rack). Is there air in the rack or is it normal?
- I'm not 100% sure when it does this, but either at cold start or after I applied vacuum several times, when I start the car I have good working power steering for the first 20-30 seconds (in this period I turn the wheel a lot). This happened several times.
- The power steering works only if I rev the engine to 2000-2500 rpm but at this point the pump whines. Of course I have no problem when steering in motion. Cold start keeps the idle at around 1100 rpm.

One last strange but important thing to mention when applying vacuum to the power steering reservoir (engine off):
- if the car is lifted then the vacuum doesn't change no matter if I turn the wheel lock to lock or hold it to lock positions
- when the car isn't lifted, if i turn the wheel to RIGHT lock and hold it there - nothing happens
- when the car isn't lifted, if i turn the wheel to LEFT lock (driver side) and hold it there - the vacuum drops instantly and the reservoir acts like either large bubbles or a flow of liquid suddenly rushed in. I first considered that there is air trapped in the steering rack on the drivers side (I don't know if this is possible) and tried to apply vacuum and then turn the wheel to lock to remove the air more then 50-70 times but I abandoned the idea because the fluid level wasn't dropping at all and the sudden vacuum drop was the same as the first time I did it.

Everything I did didn't improve the power steering at all. The only thing that changed was the fact that I now sometimes have the first 20-30 seconds of power steering after starting the car.

Thank you for having the patience to read everything, any suggestions are appreciated!

 

Have you checked for a pinched power steering line?
If the lines look ok you may want to disconnect both ends on both lines using low pressure air to blow them out. Possible blockage from seal material. Lastly there may be a clog in the rack itself and may be time to rebuild/replace it. Honestly i think you will have to do the latter.

 

Thanks a lot for your input!
I don't think it's a pinched power line. I checked them as good as I could, plus there is no leaking or vacuum pressure dropping when I apply vacuum with the hand pump.

Checking for blocked lines is something I'm thinking of checking first. Which one should I start with? The low pressure one from the reservoir to the pump? I understand that if this one isn't ok the pump can go "hungry" when opperating and whine like it does.
I'm curios, if this is the case, what could have blocked them so fast.

Regarding blocked lines, when the car is on the ground (engine off) and you turn and hold the wheel to lock, how much should the fluid level grow in the reservoir? For me, it only grows if vacuum is applied (in this case I have to remove fluid).

I hope it's not the rack but I'm also thinking that it could be the problem. I'll wait to see if anyone else has any other ideas.
Thanks again!

 

I have the same problem, have you fixed it yet? Power steering suddenly died after having clutch replaced. Mechanic said he doesn't know what went wrong. Maybe a bad mechanic? Not too sure but power steering pump is still running strong with no leaks and no whines. I'm thinking its the rack. Have u replaced the rack yet? Thank you