How To: Power Steering Flush on F250

Flushing the power steering on a 7.3 is pretty easy. It is very similar on 6.0, 5.4 and 6.8 trucks, but not identical.

The basic principal is make the system flow fluid out, while you simultaneously replace the fluid, eventually being left with only new fluid in the system. The power steering system in a 7.3 works in conjunction with the power brakes, or "hydoboost."

First a little bit of basic mechanical reasoning. A pump creates flow, which if restricted by available volume, will create pressure. Imagine a water pump. If the water simply poured out the outlet it would be moving at a rate of # gallons per minute. But if you put a pipe on the end, all of a sudden the flow is restricted, creating pressure. That is basically how a hydroboost system works. It takes the pressure from the power steering pump. This is done on the diesels because diesel motors do not create their own vacuum, which is what powers brakes on a gas motor.

The power steering system does not use power steering fluid; instead you will be using Mercon V automatic transmission fluid. This sounds strange I know, but ATF is a better hydraulic fluid than power steering fluid, making it the better choice when combined with the hydroboost system.

Do not be confused about brake fluid. Brake fluid is the fluid that actually squeezes the beaks together, and the 7.3 also has brake fluid. This will need changing periodically as well.