Brake problem

About 3 weeks ago my brake light was coming on intermittently. I checked the brake fluid level and it was down toward the "min" level, so I just top it off and figured I'd keep an eye on it. We'll today the level was back down to "min" so I topped it off and checked for leaks, tracking from the brake cylinders back to the source. No leaks detected.

When I press on the brake pedal with the truck running I hear a whoosh coming from the brake booster area. I've noticed the brake pedal has gotten gradually softer and lower over time. Im thinking the master cylinder has leaked into the brake booster and f-Ed it up.

Am I thinking right on this? Could there be something else I need to look at.

 

Did you blow a Brake line maybe ? First thought

 

master cylinder and or brake booster bladder is ruptured and thats where your brake fluid is.

 

No brake fluid seen anywhere, tracing lines from each wheel back.

 

Look down where the pedal goes through the firewall, er I mean bulkhead.

 

Exactly what I was thinking. Is there a way to confirm this? I ran the engine, press down the pedal, then tuned the engine off and the pedal continued to sink (I believe that indicates a bad booster). It seemed okay on the other tests..don't have a gauge for a vacuum test.

 

Didn't, seen any fluid inside the cab...I'll see what I can see up the firewall.

 

it should get solid when you pump the brakes and the vehicle is not running...if it doesnt build up then you have a leak. What happens a lot of times is the master cylinder leaks then the bladder weakens from the fluid and then it leaks.

 

If your pedal sinks, it's bypassing and more than likely leaking which in turn will take the vacuum diaphragm with it.

 

Thanks for the input, everyone. Pretty much confirms what I suspected.




I guess I'm gonna replace the MC and booster. Anybody have a good parts source?