Really hard break pedal 93 f250 7.3 idi

[mustangmatt89]

So I have a 93 f250 7.3 idi. Over the winter I got an extremely hard break pedal. I figured it was just the booster since I saw the master cylinder leaking on it a little so I replaced both. I still had the hard pedal. Also my heating vents don't change until I get up in rpms driving and that is when I usually have one push with the power brakes, and then I am back to manual. What pressure should these things be operating at? I am thinking it is my vacuum pump. I hook a vacuum gauge to it and I have 5 ibs at idle, and close to 10 ibs if I rev the engine a little. Any suggestions?

Also this is the first time I've posted on here in a while. I posted a lot when I was redoing my truck a few years ago. This is an awesome forum!! Glad it is still here!!

 

[Bashby]

Either a bad vacuum pump or a vacuum leak. Probably the pump

 

[mustangmatt89]

Thanks for the reply, I am pretty sure it is the pump but wanted to see what others thought about it. When I pull one of the hoses off I can usually here it drop in pressure. Also my gauge only ready 5 ibs and I thought that was really low while it was running.

 

[mu2bdriver]

Also my gauge only ready 5 ibs and I thought that was really low while it was running.

5" is essentially zero. At sea level at idle you should be pulling at least ~21" and usually more.

 

[blacksmoke94]

I'm actually going completely through my brakes right now and it definitely sounds like the pump or a horrific leak. Check around on prices as I found them anywhere from $93 to over $600 ( a misprint I hope ). Be sure to get a good puller for the pulley. I was told I needed the power steering pump puller from the local auto parts store and it didn't work on mine. I had to run it to the local shop and give them beer money to take it off. You need to reuse your old pulley or get one from the dealer. I looked all over and could not find an aftermarket. Dealer wanted $37 I think it was. Not bad from a dealer. Be sure to check all lines and the distribution body for cracks that sits on the fender well just below the master cylinder.