Steering Wheel Is Hard To Turn

[VMF]

i noticed recently that like 6-8 weeks after i changed steering fluid steering wheel is really hard to turn. what is it? bad fluid? bad pump? or smth else? it used to be nice and soft and now eevn my 91 legend is more softer then ls400:(

[thewzdoc]

Did you use AFT? Some cars use something like break fluid (Not actual break fluid as this would eat everthing that wasn't metal) for the PS. The LS uses ATF. It may just be a coincidence and you've lost you PS pump or you rack is bad...leaks? Check the vacuum lines too.

[Rich Sweitzer]

When you changed the fluid what did you put in? Dexron II automatic transmission fluid, or better I hope, and not power steering fluid. Otherwise you may have damaged components in the system.

I've used Red Line D4 ATF synthetic in my LS-400's power steering unit with very satisfactory results. The stuff doesn't even warm up enough to expand to the "Full - Hot" mark when in operation.

[VMF]

i used dextron II type fluid........

fluid level is stable.......

[Rich Sweitzer]

A couple of long shots to look at . . . .

When you changed the fluid did you purge the air from the system by turning the wheel lock-to-lock several times while the engine was running? (Probably shouldn't have required that given the fact it worked ok for a while after you made the change, but you never know.)

Another possibility is a clogged filter screen in the bottom of the fluid reservoir restricting fluid flow in the system.

Also, is the system making any kind of noise, either consistantly or when turning the wheel. That can provide a clue as to the problem.

[VBdenny]

VMF, Another thing to check is to make sure that the hose that goes to the vacuum manifold isn't kinked. I think Lexus uses some kind of speed sensitve steering. The faster you goe, the harder the effort is suppose to become. Does it doe okay on the BQE, or just at slower speeds?

[UCF3]

Taking a shot in the dark, but isn't bleed the steering wheel part of the process, just like bleeding the brakes?

[VMF]

all the hoses are ok and no noises whatsoever...... and i did that thing with wheels while flushing and changing the fluid....

[mr_goodwrench_06]

Do all models use ATF? I sure hope not, but that may explain why I have a leaking hose. The previous owner used P/S fluid and it has a leak on one of the hoses, so I have been toping it up with P/S fluid as needed. Can I mix fluid? Should I get this flushed?

Thanks,

Bill

[SKperformance]

i don't know of any lexus that uses power steering fluid instead of atf

but i could be wrong

i would recommend checking the owners manual

and changing it immediatly

the 2 don't mix

[VBdenny]

I checked the owners manual and it specifies Dextron II is used in the PS unit. I would be very careful about putting in anything else because compatability becomes an issue.

[mig25]

Power steering does not need to be bled because it has a return hose, even if you did not bleed it, it would prime itself as you drive, because the air bubles would return to the reservoir. Brakes ont he other hand can not have air bubles because they do not have return lines , also air can be compressed , thus giving you a mushy feeling on the brake pedal.

I would say that you might have spilled oil on the pulley and it might be sliping , or you do no have enought fluid.

You can flush it, like I did on lmy LS400 90. I disconnected the hose on the side of the reservoir and plug it with a cap I bought at autoparts store. Then I disconneted the return hose and connected an extention hose I bought , any hose will do, then with the engine running have someone turn the steering wheel full lock back and fourth as you pour ATF in to the reservoir, make sure the extention you bought is redirected to a Milk Jug or so. Pour slowly about 2 qts of any cheap ATF, Walmart brand will do, let it run out for a seconds until it stops coming out. You are done. Refill with a good ATF (I Used Toyota ATF Type IV) and drive, check it every once in a while after a few truns.

[Rich Sweitzer]

I finally checked in my ’91 LS-400 repair manual . . .

The early LS400 does indeed have something called Progressive Power Steering that varies the effort required to control the steering, depending on the vehicle’s speed. This is accomplished using an “electronically controlled hydraulic reaction chamber” on the rack. Engine vacuum is not used in any way to control the power steering system.

The PPS system is somewhat sophisticated in that it has an ECU that monitors a speed sensor and in turn controls a solenoid valve that allows a varying degree of pump-pressurized fluid to bypass the rack assembly (the reaction chamber). If the steering suddenly became more difficult a low speeds I would check the connector and wiring to the solenoid valve on the drivers side of the rack. (You can check the continuity of the solenoid coil with an ohmmeter, it should be 6 to 11-ohms. If you do energize it directly from the battery (to listen for the “click”) only do so for a few seconds at a time as the thing can heat up and burn out. (The + terminal is on the right if you visualize from the connector end with the mounting tab down.)

By the way, Lexus recommends a preliminary check of the system starting with tire air pressure, lubrication of suspension and steering linkage, front wheel alignment, steering system joint and suspension arm ball joint, bent steering column, security of all connectors in the system and the power steering pump pressure.

Someone previously suggested using a cheap ATF to “flush” the system and then refill with Toyota type T-II fluid. I would personally be leery of using anything other than a Dexron compatible fluid in the system. Lexus specifies Dexron II in the power steering system at the same time they use T-II in the transmission. I would think that they would use the same fluid in both locations unless there was some compatibly issue. (Dexron and type T fluids have different friction characteristics.)

Lexus also recommends bleeding the system after changing the fluid. A procedure in the manual describes the process [basically turning the steering wheel to one lock (left or right) and holding it there for 2-3 seconds, then to the opposite lock and holding it for 2-3 seconds, then checking the fluid level, adding more if necessary and repeating]. They also advise checking the fluid for foaming or emulsification, both signs that the system has air in it or that the fluid level is low.

If you want to tackle more involved diagnosis of the problem post back with info request and I’ll provide additional data as needed.