Hey guys,

I have a 1978 Chevy Scottsdale. First of all, my brake light is on. Please forgive me for my lack of tech terms but on my master cylinder, the rear reservoir keeps going dry after about 3 days of driving back and forth to work. No noticeable leakage. My brake petal sinks to the floor and I have to pump the brakes once or twice to get pressure. When i do get pressure it is limited, then after i stop and try to brake at the next stop sign i have no pressure again. I have disks in the front and drums in the rear. Any ideas? Please let me know if you guys need more info.

Thanks,
Jeremy

You apparently do have a fluid leak and you need to find it. Look for a wet spot at the back of the master running down the booster. If nothing there, then you need to inspect the rest of the brake system more closely.




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To add just FYI: Larger rear (closer to booster) is for the front brakes and can as Hammer said leak out the back at booster. Just know the brake fluid is definitely leaking and if wet (rainy) will wash away and traces of just where can be a pill.

This is a rust belt and brake lines rust out. Usually rears first but front right would also be common. Whatever - it need finding and fixing of course,

T

PS: The idea of brakes is you don't lose them all at once but trust me that 1/2 the system isn't 1/2 the braking power as I'm sure you've noticed! Also - fronts do most of the work as you would expect.
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Tom Greenleaf - MetroWest, Boston