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Toyota 4-runner power steering
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dmunsey
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Jan 10, 2008, 9:17 AM
Post #1 of 6
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Toyota 4-runner power steering
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I have a 1990 $-runner,the power steering went out on it. I replaced the pump and pully,and it still has no power steering.Also when the brake pedal is depressed you hear a loud squealing noise,the steering wheel cannot be turned .
I checked the Chilton repair manual and get conflicting info,the book says that to bleed the system raise the car and turn the wheel 3 to 4 times each way ,then start car and repeat the same procedure. A CD that came with the book says that there is a bleeder on the steering gear and to bleed it just like brakes.Cant seem to find the bleeder.
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DanD
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/ Moderator
Jan 10, 2008, 12:23 PM
Post #2 of 6
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Re: Toyota 4-runner power steering
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The bleeder screw is on the top of the steering gear; it looks a lot like a brake bleeder screw.
To bleed the system, start the engine, turn wheels lock to lock three or four times, place wheels in the strait ahead position open bleeder screw and allow fluid to flow out until all air bubbles are gone. Making sure that you do not allow the reservoir to run empty. You may need to repeat this process a number of times, allowing the system to sit in between attempts. This is to allow any of the foaming of the fluid to dissipate.
If this truck has ABS brakes you’ll also have to bleed the ABS actuator. The ABS system uses the power steering system’s pressure via the ABS actuator to control brake pressure to the wheels.
To get the air out of the actuator, the actuator’s solenoid’s relay has to be turned on and off several times in 2 or 3 second on intervals, while the engine is running and your foot is on the brake peddle.
If not done properly you’ll burn out the relay or solenoid; Toyota has a special piece of equipment to connect to the relay to turn it on & off.
I’m not sure if you’ll get away with jumpering the relay manually without doing it any damage.
As for the squealing from under the hood; is the belt tight enough?
Dan.
Canadian "EH"
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dmunsey
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Jan 10, 2008, 1:48 PM
Post #3 of 6
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Re: Toyota 4-runner power steering
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Thanks for your help,will try bleeding the unit tonight.As for the squealing it is worse when you depress the brake pedal,the belt is good and tight.Would air in the system cause the squealing and loss of power steering?
thanks again,
Dave
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DanD
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Jan 11, 2008, 1:09 AM
Post #4 of 6
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Re: Toyota 4-runner power steering
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Yea I imagine the air could be causing this considering that air compresses where liquid doesn’t?
Dan.
Canadian "EH"
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dmunsey
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Jan 12, 2008, 11:54 AM
Post #5 of 6
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Re: Toyota 4-runner power steering
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Well bleeding didnt help,had a lot of air coming out at first,but now not even any fluid coming out. Am at a loss here,any help would be greatly appreciated.
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DanD
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Jan 13, 2008, 8:47 AM
Post #6 of 6
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Re: Toyota 4-runner power steering
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These pumps are positive displacement pumps, meaning that they (if not defective) never stop pumping fluid. They use gears or vanes to squeeze fluid and force it out from between the gears or vanes; not like an impeller type pump (engine water pump) that sort of throws fluid away from the impeller. Impeller pumps are self limiting when it comes to pressure based on their design.
For example, crimp off a hose connected to a pumping impeller pump; pressure will only go to a certain point; the pump will keep turning but it can only throw the fluid so hard and circulation stops.
A gear or vane pump will keep producing more and more pressure as the hose is restricted. That’s until whatever is driving the pump stalls (stops turning) or the hose bursts.
With you saying that there’s no fluid coming out the bleeder, indicates that this pump is not pumping or fluid is bypassing the steering gear, via the ABS actuator?
Pressure is built by restricting fluid flow at the power steering gear’s flow control valve and/or the ABS actuator.
Why I’m thinking a bad pump, is that even if the flow control valve was stuck open, it wouldn’t build pressure but fluid should still be circulating.
Have a look in the reservoir’s fill hole, whether you can see any circulation (fluid movement) inside?
If this truck does have ABS, fluid flow might be bypassing the steering gear because of a bad ABS actuator, allowing fluid to pass through it easier rather then at the steering gear?
A poor man’s pressure test for the pump is too momentarily and I mean momentarily, pinch the high pressure hose off with a pair of pliers.
With the hose pinched you should see the hose swell and the sound from the pump change. This doesn’t tell you how much pressure just that the pump is still capable of producing pressure?
The proper way of testing pressure is with a gauge that has an adjustable restrictor value and hoses that can withstand the system’s maximum required pressure; in this case approximately 1070 psi.
Be careful using the first method I mentioned; burst a small hole in the line and this high pressure fluid hits you with a pin sized diameter steam of fluid. Well lets just say that your flesh is no match for it.
Here’s a picture of a universal pressure gauge; you might be able to rent one, some part suppliers may offer this service?
Dan.
Canadian "EH"
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