VQT

Do a search on SC400 forum. I think your problem is a clogged filter at the bottom of the resevoir. Don't quote me, I remember reading something about taking the resevoir out and clean or punch a hole in the filter...it was talked in detail a few months back

lextek

Here is you guys problem when no leak is actually seen. There is a valve on the side of the power steering pump, it has two vacuum hoses attached to it. THIS WILL GO BAD. Unfortunately most Lexus techs do not quote it to the customer because they either do not know or they feel it is expensive and probably not needed. An entire power steering system can be replaced, this part transfered and presto, same freakin' problem.

The valve in question goes bad and the engine vacuum starts pulling the power steering fluid from the pump into the intake plenum slowly. That is why you will not see smoke from the exhaust. It will do this over time and you will have NO fluid in the pump and NO leaks seen. Scratching head. Sound familiar? It has kicked many Lexus techs in the you know what, when really they are very good.

Lextek.

toddatroos

Thanks for the info on the vacuum switch..... although this is not my problem. I definitely wouldn't have replaced the switch (for $230!) if I would have known it is unecessary. At the time, I thought this was the problem.

My problem seems to be some sort of blockage on the high-pressure side, preventing the fluid from circulating. The result is the fluid cavitates in the pump, foams up, and overflows the reservoir. I still have not received a definitive answer on what can be causing this. I recently had the car in a Toyata/Lexus speciallized shop. They said the high-pressure line going from the pump to the rack needs to be replaced. They mentioned something about a "check valve" in the line that plugs up. Has anyone out there heard of this check valve or of the line getting plugged? Could the solenoid be bad down at the rack, or possibly the pressure valve? Is there possibly an air bubble trapped in the system? I have cleaned the filter screen located at the solenoid valve, but it did not fix the problem.

My nice Lexus LS400 now smokes from the fuid spilling out of the top of the reservoir and onto the exhaust. I am forced to add fluid on a daily basis to keep the pump from burning up.

SOMEBODY HELP ME, PLEASE!!!!!!!!!!!!!!!!!!

RODDMOD

I see you have tried about everything, one would think that foaming would have to do with air getting into the system some where, who was doing the work? is it possiable that a o ring on the rack valve or a gasket not replaced with a new one? Good Luck lets us know what you find out.

toddatroos

I have tore into the power steering system again this weekend. I am now convinced the problem lies somewhere in the pressure control valve and/or the speed sensitive steering solenoid valve located down on the rack. I called the Lexus dealer and they get $600 for the solenoid or $650 for a remanufactured rack! I had to bite my tongue to keep from telling them to go to hell! I can get a reman rack with the solenoid for $300 on-line. Has anyone out there heard of this solenoid going bad? Should I just go ahead and replace the whole rack?

Thanks in advance for any advice.

VQT

Have you check with Steve Ganz or Gordon at 800-908-6968 for Lexus parts? Their price might be cheaper.

RODDMOD

You say you have cleaned the screen on the solenod that is mounted to the rack, what did you use to clean it? This screen is made of plastic and if you use a florinated cleaner this screen will melt, is has to be cleaned with nothing stronger than Alcohol, your problem may be that it is melted some and cloging the high pressure line, just a guess. Let us know the end of the story.

toddatroos

Success!

I did a few different things, and finally no noise or fluid foaming!

I replaced the o-ring on the reservoir, the three o-rings on the pressure check-valve housing, and the inner o-ring on the solenoid valve. The screen filter was once again almost completely blocked, so I cleaned this out again (with brake clean). The filter screen itself is metal in a plastic collar. Anyway, after I put it back together, filled it with fluid, everything worked fine! I made sure to only run the car for a few seconds at first to make sure it didn't suck the fluid level down too low.

I hope my experience with the Lex power steering system has helped others. It sounds like this is a common problem on the earlier generations of the LS. Thanks again to all the advice and help received on this forum. I estimate it saved me over $1500 by allowing me to do it myself. Thanks again everyone.

kreativ

My '91 LS underwent some power steering pump work at 60K (Jan. 99). Here's what the Lexus dealer service invoice lists:

Service:
Power Steering Pump Leaking - Resealed Power Steering Pump - Flush system $360

Parts:
Power Steering Gasket Kit (0444630172) $58.99
Pressure Por Gasket (4432712010) $5.99
Non-Cholr Brake Clnr (002892BC00) $5.99
A077 P/S Kit $35.99

silver400

For those of you with crapped out idle-up valves, and are interested in leaving it in place and looping it off to itself, as discussed earlier in this thread;
The stock hose is a vacume hose, too light weight to handle the heat and pressure of PS Fluid. I replaced it with a loop of thicker, higher strength hose a few days ago, and so far, so good, it has not ruptured. I may end up replacing the damn valve, but at this point, I may have solved it.