Ok, this is a third party question for a buddy not on the HAMB. On a 60's Dodge pickup, the pedal is spongy and when pushed fluid pushes out out around the master cylinder cap. Brake system is front disc rear drum. Front suspension/ brakes are Mustang II style- rears are stock Dodge truck 11" drums. Booster is from Pirate Jack originally for a Toyota FJ. The mount bracket matches the Dodge truck perfectly. Master cylinder is the universal Hot Rod Corvette 1" bore with the matching proportioning valve and residual valves front and rear. Every line and fitting and all the aforementioned parts are new. The system has been gravity bled, pressure bled, vacuum bled and old school two man pump the pedal bled. Help solve this mystery for us!
I've not experienced this but, fluid pushing from the master cylinder cap would lead me to believe the master cylinder is faulty.
Well it looks like has done the seemingly impossible. I've seen fluid come back out that way when the pedal was released and the piston pushed the fluid back into the reservoir and it overflowed because it was filled a bit too full. Rear brakes correctly adjusted? I've fixed too many owner worked on it and the brakes don't work right rigs that the drum brakes weren't adjusted right on. Usually because the owner doesn't want any drag on the shoes against the drums. That also causes low pedal and mushy brakes because the pistons in the wheel cylinder have to move so far to get the shoes to contact the drums.
Thanks for your reply. My buddy is a long time pro with his own shop & a million drum brake jobs under his belt. It is certainly worth checking again to make sure.
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