hydroboost diagnosis test
I have been having a problem with my brakes here lately and i am in the process of taking it in for a diagnosis.The problem is the brakes doesnt seem to have the stopping power they should have and th...
Forum Discussion
darsben wrote:
hydroboost is for the power on the power brakes.
Brake fluid an entirely different system. No interconnect. You can change brake fluid without worrying about the hydroboost
True about the fluid changes, but if it's a HYDROboost, it's a hydraulic booster driven by the Power Steering Pump. Not a vacuum booster driven by manifold vacuum. I've heard an OP claim that PS fluid escaped the hydroboost and got into the brake fluid, but it's hard for me to picture how that could happen. Back of Brake Master Cylinder bolts to Front of Hydroboost and they're both built to retain their respective fluids.
From Joe's previous posts, this Thor Pinnacle is a Class A, on Chevrolet P30 "narrow" motorhome chassis with disc front, dual rear drum brakes.
Might be hard to repeatedly "get pedal" with the engine off since the hydroboost's reserve pressure will go away. Just PRESS the brake pedal if you bleed brakes with engine running. Hydroboost produces WAY more pressure than Vacuum Boost.
We had an OP with problems bleeding brakes on a Ford based Class C that had Hydroboost. It was actually an ABS problem but he decided to replace the Master Cylinder while the system was open. He reported that he had better pedal with the new cylinder than he'd been getting before he started all the brake work.
Again, just for me, with suspicious behavior and a 20+YOA master cylinder, I'd change it, bleed everything, adjust the rears, see what it does. Master Cylinders seem to price around $50.
Quick check on 1992 P30 with 7.4/454 engine shows a reman hydroboost $175, looks like this?
Just for me, even if it is not getting full boost, there's a master cylinder problem (or a brake/brake line leak) IF the Brake Warning Light is coming on.
