I bought an 04 F150 SCrew 5.4 3V a while back. The power steering fluid level keeps dropping. I have topped off the power steering resivour at least 3 times in the last month and a half.

What's got me baffled is I can't find evidence of a leak anywhere. The hoses, the pump, or on the belt. I've crawled over & under it. I can't find anything anywhere.

Anybody got a suggestion?

 

There has to be a leak somewhere. I don't know where you park, but check for drips on the floor or put a sheet of cardboard or something under it you can check.

I have an 04 that I just had to replace all the PS lines on because they were badly rusted and weeping fluid

 

On my vehicles with fluid power steering, I use a vacuum canister to remove the fluid from the reservoir, then I refill with new fluid. Maybe once a year on the newer ones and more often on the older ones. This helps the system to last longer without leaks or corrosion. This method doesn't change all the fluid at once, but accomplishes the change as it is repeated over time.