I just replaced all 4 rotors and pads and I think that my master cylinder is in need of replacement. When I brake hard/panick brake it seems to almost loose pressure after a second or two on the pedal. I have replaced the hydro boost and power steering pump about a year and a half ago so I think they should be good. I took my truck to a shop to see what it would cost to have them replace the master cylinder.

The tech hopped in the truck and stepped on the brakes and tried to turn the wheels and he could only turn the wheels about 1/2 -3/4 turn on the steering wheel and it would lock up. As soon as you let the brake off it turns fine. I told him I had replaced the hydro boost and power steering pump and he suspects that the steering box is the cause of the locking of the wheel when on the brake. He said there is some kind of valve in the steering box that could be causing it to lock up.

Does this sound like a possible cause for this? Has anyone else seen this problem before and know what fixed it?

I was planning on replacing the steering box or adjusting it because it has some play in it. I was hoping I could get away with just adjusting it for now.

Thanks for any and all help on this.

 

Turning the wheel while stopped is almost a total no go on my truck and I think it's that way for all of us.

 

Thanks for the input, that is why I posted to see if this is a normal thing when on the brakes you can't turn the wheel stop to stop. I don't ever remember if my truck was able to do it or not. I am normally rolling and not fully locked up on the brakes when turning.

 

I cant turn while stopped, and i have a feeling my steering box is original - it's pretty loose. Do you know how to adjust the steering box? It's really easy, there are a few OK videos on youtube.

 

So it sounds like this is a fairly common thing not being able to turn the steering while on the brakes.

I have done some research on how to tighten the steering box but might look at you tube also.

 

It is pretty hard on your steering linkage, pump and gear to turn the wheels while stopped anyway, especially with 1K lbs of engine on top. Just hearing the pump complain is evidence enough. I have a habit of never turning the wheels without moving, even if it is just a little creep.

 

It's really easy, there are a few OK videos

 

Ford engineers obviously decided that it was ok to load up a marginal power steering pump with the responsibility of also providing braking assist. All diesel super duties with stock pumps will protest when much is asked of them. You are not alone.
Larry