2005 H2 Question,
My wife was sitting in the school pick up line for over an hour idling, stop and go. All of a sudden she heard a popping sound, brake pedal went to the floor and lost power steering. I had it towed home and noticed fluid all over the drivers side under the hood. Power steering pump was empty. I refilled it and bled the air out. No leaks to be found. Let it sit about 2 days and now when it starts the brake pedal will go to the floor fairly easily and vibrates when it bottoms out. No lost fluid in steering or master cylinder. I can't figure out how it lost the power steering fluid. Pump and gearbox were recently replaced. Brake pedal has had an intermittent kick back on brake pedal application for some time with occasional abs and traction control lights coming on. Every time I bring it to a shop it doesn't duplicate the issue. I am not sure where to start. Possibly hydo boost issue, or abs module, or both. Any ideas are appreciated.

 

it does sound like a hydroboost issue kickback on the pedal is one of the symptoms of a failing hydrobooster.

 

Could I have somehow lost power steering fluid through the hydro boost?

 

Hydro boost, hoses, drivers side shock tower were all soaked with power steering fluid.

 

When the hydro-boost fails, you still have braking ability, yet end up with manual braking(no assist). When the master cylinder fails, your pedal will go to the floor, with no braking ability. Inspect your brake fluid for improper fluid contamination. If contaminated, replace master cylinder and make sure to flush the system.

 

The brake fluid is good. The brake pedal feels good after it is running for a few minutes. Only after initial start the brake pedal sinks. Bigger question would be how and where did it lose the power steering fluid? It was bone dry in the pump reservoir when initial problems started. Once I refilled and bled the steering system I cannot find any leaks. I degreased the engine compartment today and ran the truck with no leaks. I just can't send the wife driving until I figure this out. Thanks for your input but as of right now it doesn't seem to be a master cylinder issue. I know these trucks are notorious for abs module failure as well but I don't believe that would relate to power steering fluid loss either. Is there a purge valve somewhere on the hydro boost unit that I am not seeing?

 

How does the brake pedal feel when not running?
You noted brake pedal to the floor, and power steering fluid leak drivers side?
Post some pictures!

 

Brake pedal feels good with the vehicle not running as well as while running after a few minutes. It only drops when first started. When it initially had the issue it happened quickly. Something made a popping sound, the Brake pedal went down and lost power steering. I am quite sure the braking issue is directly related to the power steering fluid loss. Once I can figure out what happened with the fluid I am sure the Brake issue will be rectified. I can't see 2 problems happening at the same time but with my luck it may.

 

there are some procedures here https://www.brakeandfrontend.com/ope...ssist-systems/