I have run across this problem before...
I suspect you have a frozen wheel cylinder piston, when the brake pedal returns, a vacuum is created, allowing air to suck past the
wheel cylinder cup seal....Check all wheel cylinders for freedom of movement....Give it a try.....


My GMC has a bad case of ship fitters disease!
GMC: Get More Cash...
1958 GMC
1956 Chevy 1500 Hydraulic Dump Truck
1952 Chevy 1700 3-Ton Firetruck

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