Super man Brakes.

[trail mule]

The brakes on my wagoneer feel very hard. I almost need to stand on the pedal and push down with my hands just to be able to sort of stop. When I press on the brakes I hear a hissing sound and my rpms go up. I checked for leaks and there are no leaks. I also bled the brakes and they are good but it is still really tough to stop. What is causing this problem?

[JeepsAndGuns]

Your brake booster is bad. The hiss when you push down on the pedal and the rpms going up is the vaccume leaking past the boosters insides.

[orangecherokee]

check the vaccum line to the booster.

[Chevelleguy]

Your brake booster is bad. The hiss when you push down on the pedal and the rpms going up is the vacuum leaking past the boosters insides.

X2

[bowtieman55]

Your brake booster is bad. The hiss when you push down on the pedal and the rpms going up is the vaccume leaking past the boosters insides.

x3

[Stuka]

That or you don't have power brakes at all. Non-Power brakes were available up until '75.

And if your RPM go up when the booster leaks, it means you are running way to rich ;)