Power steering pump is leaking and am going to replace it. What is a good procedure to flush the system if the hoses and cylinder are sound?

 

This procedure describes how to “flush” old power steering fluid from your steering system and replace it with new fluid. (I always recommend that you refill with genuine General Motors power steering fluid.) This procedure works for all power steering systems (i.e. Corvette valve and adapter, integral power steering gears, and power rack and pinion steering gears.)

GETTING THE OLD FLUID OUT
Jack the front end up so that the wheels are off the ground but free to move from full lock to full lock. Suck as much fluid out of the pump reservoir as you can. Remove the return hose from the reservoir spout. Cover the spout with tape or use a rubber stopper to avoid spilling more fluid. Direct the return hose into a pan or bottle. If the hose is very old, you may find that the rubber cracks when you try to redirect it.

DO NOT start the engine. Have someone rotate the steering wheel full lock to full lock. This should "pump" fluid out of the return hose. After a few revolutions you should start getting air and oil out of the hose.

You have to remember that now that you have pumped most of that old oil out of the system, there will be lots of air that has entered the system in its place. For the most part you should have expelled nearly all of the original fluid. If you want to do a super job, add some GM power steering fluid to the pump reservoir and use the full lock to full lock procedure to work this fluid through the system as a flush.

REFILLING THE SYSTEM
Remove the tape or stopper from the reservoir spout. Reattach the return hose. Fill the reservoir with GM power steering fluid. Now use the full lock to full lock procedure to begin pumping fluid out of the reservoir and into the rest of the steering system. You will find that you will need to refill the reservoir several times since fluid will be "pumped" through the system and air will be coming up into the pump reservoir in large bubbles. You may need to rotate the steering wheel a couple dozen times to replace the air with power steering fluid.

When the level in the reservoir stops going down and air bubbles stop showing up in the reservoir, install the reservoir cap. Now you can drop the front end down and start the engine. Rotate the steering wheel full lock to full lock a couple times. (Do not hold the steering wheel at full lock for more that just a couple seconds each time.)

Recheck the fluid level and refill as needed. Check for leaks and then go for a short 10 mile drive. You should be ready to go!

JIM

 

Why do you recommend to DO NOT start the engine? Taking care that there is fluid all the time in the reservoir would be faster, right?

 

The pump will defuse the remaining air giving you thousands of tiny bubbles that will need to dissipate before driving.
The tiny bubbles will be throughout the entire system, not just the reservoir. Just turning the wheel lock to lock will not do that.

 

With the front wheels off the ground, you can easily rotate your steering wheel full lock to full lock. The assist cylinder (Corvette power steering) or the integral power gear (all other GM cars and trucks with power steering) will act as a pump and move the hydraulic fluid throughout your power steering circuit. It will also push large air bubbles through the system until the air bubble(s) reach the pump where they will rise to the surface of the fluid in the reservoir and back to atmosphere.

If you start your engine, those large air bubbles pass through the pumping section of the power steering pump and get whipped into a froth with millions of very tiny bubbles. You now have power steering fluid that is compressible. This causes much pumping noise, and prevents you from obtaining full assist pressure.

If you start your engine with lots of air in the system, it usually takes a day or two for the small air bubbles to naturally work their way back to the pump reservoir.

Jim

 

My way isn't perfect but it worked for me. I was able to replace all my fluid and im pretty sure I got rid of all the old fluid.


1. Go on a long drive
2. Blow the return line about 45 minutes away with out realizing it
3. Keep driving it home and wonder why the steering feels stiff about
1/4mile from the house
4. pull into the driveway and check the fluid
5. Replace the missing fluid
6. Start the car, turn the wheel and make a puddle in your driveway
7. Go order new hoses
8. Replace and refill
9. repeat step 6, do not make a puddle
10. Go for a ride, do not repeat step 2.

 

The power steering pump does not like to be spun dry. You are fortunate that the cam and plates inside the pump haven't seized and the driveshaft bushing isn't scored. Obviously, you know have a fresh supply of power steering fluid since all the original (or old) fluid was expelled on your 45 minute ride home.

BTW, I have always recommended filling or refilling your system with genuine GM power steering fluid (GM 89020661) for a 32 fl oz container. Your system should take 21 fl oz if if it is empty. It is the only power steering fluid that is specifically designed to operate with the Saginaw line of power steering pumps.
Jim

 

I definitely got lucky with that little fiasco. That was a couple hundred miles ago and still no leaks and it works fine. So I am truly lucky.

Thanks for the info

 

This is one of the best posts I've ever read anywhere! So funny!

 

I forgot about that...i need to save it...it made me laugh too!!