I have a 1995 f-350 crewcab with 7.3 turbo powerstroke diesel with 225,000 miles on it in very good condition. I recently drove thru approx 16" of water about 6 times. Now the brakes are acting like there is no power to the power brakes, very hard to push down the pedal. Once I reach 65 mph and up they feel fine and work good but when I slow down pedal gets very hard to push down again. I've never had any brake issues in the past. I've replaced brake pads when necessary and the rotors once. I've done routine maintenance to it. Replaced glow plugs once and had transmission rebuilt twice. Other than that is is stock.
I'm thinking vacuum line to booster leak or vacuum pump going bad. Any other ideas. I'm going to check it out this afternoon. I've worked on my vehicles all my life. Just looking for additional input before I start on it.

 

Welcome to the site,

I'd be suspect of the vacuum pump.

 

The Vac pump is easy to check. It is located on the passenger fender. When you move the vent control **** do you get a corresponding movement of the damper in the air handling duct?
When you first turn the ignition to on (wait to start illuminates) do you hear the vac pump running for 10-15 seconds?
You have a significant symptom so the spolution will be direct.
Eric

 

ahh shucks,
"spolution"
Now thats a new one!! Solution is what I meant.
Eric

 

Jump'n ahead a few years Eric.

Those Ol 7.3's had belt driven vac pumps..

 

Oh goodness, yes of course. My apologies and thank Hay for the correction.
Regards,
Eric