Hello!Tonight, I had a major scare when I lost the brakes in my 2004 GMC Sierra 2500HD. The brake pedal started to get spongy, then went to the floor. The Driver Information Center advised to Service Brake System, and the brake system‘s Idiot Light went on. I pulled over and checked the brake fluid reservoir and found it to be more empty than full. My question . what is the likelihood that the brake fluid may have evaporated over time as opposed to a leak having developed someplace in the brake system?In advance, thank you for your advice and input!
If you have a leak, which it sounds like you do, it's a serious problem. For one, pressing the brake pedal causes the brake booster to assist you in pressurizing the brake lines using vacuum from the engine's intake manifold. With the extreme pressures running through the lines, a leak will cause your fluid to leak rapidly when you press the pedal, and it will also prevent the brakes from working when you do press the pedal for the first time, due to the fact that no pressure can build. Look for the leak, it's most likely behind one of your wheels, where there is a rubber hose. The metal brake lines generally don't leak unless they get rusted through, and that generally is not the case.
Brakes wont get spongy from just low fluid in the reservoir. If it gets really low its possible to get spongy but it does not sound like yours were that low. What is more likely is that you have a leak somewhere and besides leaking fluid its also letting air into the system which is what is making the pedal soft. Get it towed somewhere to get it fixed, unless you know exactly what the problem is its not worth the risk that they will quit completely. Also get it fixed as soon as possible. The longer there is air in the system the more damage it will do and the more stuff will have to be replaced when you decide to fix it.
the consistency of the brake fluid will not evaporate. quite sure you have a leak at any of your wheels and the fluid leaked out. therefore you lost your brake pressure. look around your tires and most likely you will find a puddle or a weep leaking down from a hose,caliper or wheel cylinder. later!
