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Power Steering/Hydro Boost Fluid Flush


350,000 Worth and counting
Staff member
Lead Moderator
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Sandwich, Illinois
This is compliments of Heartbeat Hauler (Jeff) and I've put a bit of editing into it as well as photos .
Under the hood on the driver's side next to the fire wall up high there is a rubber return line w/ a spring clip holding it on. It's real obvious and the only one there. Put some rags under the hose and around it when you pull it off or it'll be quite a mess. I removed the clip and hose, then attached a piece of clear 3/8" tubing 6.5ft long onto the fitting using a small hose clamp. Ran the other end to a catch pan on the floor. Alternately there is a pic below of how to do a hose to an empty gallon jug. Start the truck, in park, slowly depress the brake pedal as far as you can and hold it. Then turn your steering wheel clockwise 1/4 turn, back to center, then 1/4 turn counter clockwise then back to center. Slowly release the brake and re-apply and turn steering wheel again. Continue this until you hear the pump make noise (mine took 3 iterations). Stop immediately and turn off truck. Fill the power steering reservoir with fresh power steering fluid ( I used NAPA brand which is actually valvoline $12.99 a gallon. Mar 2012 that was up to $17.99). Then repeat this procedure until you see clear fluid coming from the hose. Make sure that you put something on the hose in the catch pan to hold the end of the hose in the pan. Or drill a hole in the cap about 1/64" smaller than the tube per the picture below. Mine took a little over 3/4 of a gallon. Probably more than I needed but I wanted to get as much old stuff out as I could, and like I said, the old fluid was BLACK! Then, remove the clear hose and reattach the rubber return line. Also, make sure there is enough new fluid left over to refill the power steering pump when you're done. AND, after you refill for the final time, start the truck and move the wheel back and forth, then recheck fluid level, add if needed. All done.

Here's the clear tube hooked up and clamped. I made a mess for starters...
PS fluid1.jpg

Here is about 1/2 done
PS fluid2.jpg

The hole in the cap is about 1/64" under the tube OD
PS fluid3.jpg
Last edited:

Mad Maxx

See, what had happened was...
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Long Island, NY
Just did this method today and it worked like a charm!

Fluid that came out was a nasty Brown / Red.

Def tightened up my steering and made it feel ALOT better.


New Member
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Northern Illinois
Hi guys, looks like this thread might have a little dust on it.
Will this process work with a dry system?
I just replaced the lines, had the booster and reservoir out and cleaned up, so there is no fluid at all in the system now. Is there a different process for bleeding the air out to began with or will the described process work the same?
Thanks guys.


Well-Known Member
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Pendleton, SC
I think you have to this to burp the hydro boost and purge air. I did it installing a new hydro boost that was empty.


Well-Known Member
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Grand rapids
I used the idea of the hose going into the gallon hug. Worked great. Could see every bit of air and fluid coming out till if was a nice steady flow. Thanks for the write up. :)

Big T

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Fullerton, CA
I finally did this on my '99. Wow! Of all the stupid brake improvements I've done, this bleeding of the hydroboost made the most difference by far. Lot of air came out and bleed it until it was new clear fluid. Only concern was that after many iterations and topping off the PS reservoir, usually on the third iteration of pumping the brake and turning the wheel back and forth, I'd get fizz in the line and the reservoir was closer to full than empty. Finally called it done when the fluid was all new and took it for a drive. The ABS is not working, so I was able to lock the wheels in a step from 50 mph. Not able to do that before. So I'd call it a success.

Now I'd like to fix the ABS, but that has been the perpetual mystery.