E450 MH Brakes

[29BMinnie]

I've been through so much with my E450 brake system lately that I can't remember how they used to feel or act, so I'm asking for other E450 users input to refresh my recollection.

Before I ask, I'll yield some background information. The MH is a 2005 Winnebago Minnie 29B on a E450 Super Duty chassis. The front brakes have been replaced and rotors turned, the rear brakes checked and the system bled. The brake pedal is firm with the engine off, but when I start the engine the pedal becomes soft with the transmission in park or any gear. Depressing the brake pedal while the engine is running also produces a hissing noise, probably from the power assist unit. This unit does not use a vacuum booster. It has a hydro booster that runs off of the transmission. When descending a hill while in drive, there is little or no hissing noise when the brakes are applied. When using engine braking, the hissing noise appears when the brakes are applied. The coach seems to stop alright, but I'd be concerned if I had to brake real hard or panic stop.

Question: For all you other E450 chassis owners - is this how your coach works?

[theoldwizard]

What year, what engine ?

Are you certain about the hydro booster ? The only ones I know of ran off of the power steering pump.

If you had a vacuum booster, I would say your pedal feel and hissing noises were Identical to my E150.

[29BMinnie]

The MH is a 2005 with a gas V10. You're right, the hydro booster does run off of the power steering pump. My bad.

What I don't like about the pedal feel is that it can go almost to the firewall. Never seems to firm up unless the engine isn't running.