H3nleY Posted April 8 Report Share Posted April 8 Hey all! So here's my sitch. New master cylinder, only fluid comes out from all four corners when bleeding, no air. Have adjusted all four drums and wheels slightly drag when jacked up. If I press the brake pedal with the truck running, the RPMs will drop and near or fully stall the engine. The brakes only actuate near the floor but the pedal always comes back up and never drops. Do these symptoms point to a bad brake booster or check valve? Or does it sound more like a vacuum leak in the booster hose? I'd like to know exactly what to look for when I go back out to work on the truck. Thanks y'all! Quote Link to comment
datzenmike Posted April 8 Report Share Posted April 8 Pull the brake booster hose off the booster and seal it or have someone hold their thumb on it. If it still stalls then there is a problem in the hose. If it's ok then the booster is leaking. 1 Quote Link to comment
H3nleY Posted April 8 Author Report Share Posted April 8 3 minutes ago, datzenmike said: Pull the brake booster hose off the booster and seal it or have someone hold their thumb on it. If it still stalls then there is a problem in the hose. If it's ok then the booster is leaking. Just to clarify, seal the hose once it's off the booster, correct? Quote Link to comment
datzenmike Posted April 8 Report Share Posted April 8 Yes close off the open end of the hose. This removes the booster. If the engine runs then the vacuum leak is probably the booster. If still bad you know it isn't the booster and must be in the two hose lengths and the one way valve, possibly the hse clamps. Is this truck an automatic? Quote Link to comment
H3nleY Posted April 8 Author Report Share Posted April 8 4 hours ago, datzenmike said: Yes close off the open end of the hose. This removes the booster. If the engine runs then the vacuum leak is probably the booster. If still bad you know it isn't the booster and must be in the two hose lengths and the one way valve, possibly the hse clamps. Is this truck an automatic? Nah, it's a 4-speed manual Quote Link to comment
datzenmike Posted April 8 Report Share Posted April 8 Just asking because automatics have a small vacuum line to the transmission modulator valve. Quote Link to comment
H3nleY Posted April 17 Author Report Share Posted April 17 In case anyone is dealing with this too, my issue was my brake booster. It must not have been holding vacuum anymore but once I put another one in, the issue was fixed! 1 Quote Link to comment
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