Power steering fluid in P/S, Ok to flush and change to ATF?

[triumph406]

Hi All,

I'm changing out the steering gear on my 2001 7.3.

The previuos owners reciepts show he had the power steering pump changed, and the mechanic used power steering fluid according to the receipt.

If I do a complete flush and change to Mercon V will there be a problem, or should I just keep on using poer steering fluid??

Thanks in advance for any help!

[PolarBear]

ATF is what is supposed to be used in the power steering system. If you do a flush then I don't think there would be a problem.

[99PSD-White]

It wont hurt anything. I did the same and asked my buddies dad which is a mechanic, and he said its fine.

[triumph406]

Thanks guys!!

I did a complete flush of the system by putting some 3/8 id vinyl tubing on the hydroboost return line. It took 3 quarts to flush the system and fill it up. I gotta say it was a complete PITA to get the air out of the system!!!

I changed the PS fluid to Mobol 1 synthetic, I thinking I might have been better off just using normal (non-syn) Mercon V, I'm hoping I haven't created any compatibility issues by changing the PS fluid to MerconV

Thanks again!

[mas360]

It would be nice if you describe in details of your flush procedure. I'd like to flush mine.

Thanks

[triumph406]

Originally Posted by mas360

It would be nice if you describe in details of your flush procedure. I'd like to flush mine.

Thanks

It's pretty simple. On the hydroboost unit there's a low pressure return line, that's clamped with a spring clamp. Take the clamp off, and then pull the hose off.

Next use 3/8id vinyl hose, slip one end over the nipple on the hydroboost unit, and put the other end in a container.

Start the engine, with it idling, pump the brake pedal a few times. Stop the engine, fill the power steering pump resevoir and repeat. You also need to raise the front of the truck off the ground, and cycle the steering lock to lock to circulate fresh fluid. When you pump the brake pedal, you'll get probably 3 oz's of fluid come out at a time. Be very carefull you don't run the pump dry, as you'll then have to get the air out.

Keep pumping the pedal, and refilling the resevoir until you get fresh fluid come out of the hose. It takes about 15-30 minutes to do. I would get the tubing from ACE hardware. Good luck!

[mas360]

Is the brake system connected to the power steering somehow?

Wouldn't it be faster to suction out the old fluid in the power steering reservoir first and fill it up with new fluid before starting the procedure?

I have not looked at it but I guess there has to be two lines between the cooler and the pump resevoir. How do you tell which line is the low pressure return line?

[nine54]

The low pressure line he's talking about goes into the top of the master cylinder. Take a look under your hood, its the only rubber hose that comes off the top of the master cylinder just behind the brake fluid reservoir. Power steering pump provides fluid for the power brake assist.

[triumph406]

Originally Posted by mas360

Is the brake system connected to the power steering somehow?

Wouldn't it be faster to suction out the old fluid in the power steering reservoir first and fill it up with new fluid before starting the procedure?

I have not looked at it but I guess there has to be two lines between the cooler and the pump resevoir. How do you tell which line is the low pressure return line?

The power steering pump supplies the hydraulic pressure req'd by the hydroboost unit. The hydroboost unit is the unit that provides the braking assist. By using the hydroboost return line you can quickly (relatively speaking) change the fluid.

The other method is removing the fluid from the resevoir using a turkey baster, and putting clean fluid in. I think the bleeding from hydroboost unit is faster, and a more complete method of changing the fluid.

[mas360]

Thanks for the lesson. I learn a little bit everyday....)