With the engine running, vehicle not moving and medium pressure the brake pedal will go all the way to the floor. When driving brake performance is good, stops well and ABS will come on.
Dealer says pedal going all the way down is normal, related to hydro-boost system.
I am concerned - how can pedal go all the way down if there is not something wrong with the master cylinder?
"Reno" schrieb im Newsbeitrag news:Xns9ABA96412B963REGS@24.66.94.159...
Have your checked break fluid level? I haven't driven the Hummer yet, but this is signification for air in the system.
Regards,
Ralf
Yes, you can force the pedal to go all the way to the floor. You can do that in most any vehicle with highly boosted power brakes but it is a pretty stupid thing to do as you will end up blowing the seals or hoses out eventually.
Steve B.
So let me get this straight..brake pedal goes to the floor with the vehicle running, so what do you do, you DRIVE THE THING? What state are you in? What city? I don't want to be driving anywhere near your street-legal road tank.
And thanks for confirming only idiots buy hummers..how's your gas mileage BTW?
Chris
No hummer here, but I have a 3500 dually pickup with hydroboost and it definitely doesn't behave as you describe. Pedal behavior at idle is pretty much the same as at speed, and it will not go all the way to the floor unless there is air in the system.
I'd test drive a hummer at a different dealer or two to confirm that it's not a design "feature" on that vehicle, and if the others behave properly then I'd pressure the original dealer to fix it and / or contact GM direct.
The only difference with hydroboost is the source of the assist pressure. In a vacuum system it is vacuum on the diaphragm and atmospheric pressure on the other that give you the assist. In a hydroboost it uses the hydraulic pressure from the power steering system. The rest of the brakes are the same.
How about this. With the engine OFF what does the pedal do when you step on it? You say that the ABS comes on. What are the road conditions when it comes on?
Try it tomorrow and see how far you can push the brake pedal. We had a fleet of astrovans and you could push them all to the floor with the engine idling if you wanted to. The vans all stopped normally with normal pedal travel but you could push the pedal on down to the floor if you tried to. These were all new vans. I think this is what the OP is doing, but I could be wrong.
Steve B.
Nope, no difference in pedal behavior between idle and moving. The pedal does not travel more than about half way under any sane amount of applied pressure.
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