I recently finished replacing the PS pump, rack and pinion and alternator on my 1995 SC400 (166k miles, no power steering). I got everything back together and took it for a drive, everything was going fine for about a minute when the power steering just shuts off ....I drive around for a little and find that it keeps randomly shutting off completely and then coming back on completely...very weird

So I just got in from trying to troubleshoot/re-flush any air out of the system and it seems that it is shutting off after it drops below 500rpm's (very specific). For example, when in park and the RPM's are up, the PS is working fine..but if I put it in drive with my foot on the brake, the rpm's drop below 500 and it shuts off even if I kick on the A/C(the RPM's jump up just a few revs) it will start working again.

I thought for a second that I maybe crossed the vacuum lines that go to the PS pump/intake but I tried it both ways and the car still does the same thing.

Anyone have any idea on what could be causing this? I mean its either completely off or completely on, so it seems like a sensor/ECU thing..

BTW, Aliga helped me with some parts that I needed, great guy to do business with! Thank you!

 

Anyone have any ideas/troubleshoots?

 

well, since I'm working on some power steering problems myself - I'll chime in. Best I can figure is that the fluid is low (lesser of the two thoughts) or that the filter in the fluid reservoir is clogging up and unclogging just enough to block fuild passage for a moment here and there. This seems like the more likely of the two after reading that it seemed to happen when the RPMs were down. If there is a bunch of stuff in there clogging up the filter then high RPMs would force more fluid with more agitation into the filter area possibly unstopping it up - then with the low rpms and less fluid pumping it clogs... just a guess but it seems possible to me.

There are some flush tutorials around - such as http://www.lexls.com/tutorials/steering/ that should send you in the right direction if this is indeed the case for you. At the very least it's a bit of inexpensive preventative maintenance that you'll feel good about having done regardless


In my case - I'm trying to find out what the top hose (the thicker one) that comes out of the power steering pump and into the fluid reservoir is called, and it's part number so I can replace mine. Mine burst open right before the clamp that hold the end to the pump it's self and barfed out all the fluid all over that side of the engine bay - fun stuff.

 

sounds like it's low on fluid and/or air trapped in the rack....try cracking line lines loose at the rack and letting any air burp out, then crank it up and hold it full left for 30 seconds then full right for 30 seconds then recheck the fluid level....if the fluid is foamed up, it'll take a day or two of driving for the air to burp out.