Brakes - pedal needs pumping - no fluid loss - ????

Took the bus out for 40 mile trip today - brake pedal spongy and needed pumping - once pumped foot hard on the pedal and its rock solid. There is no fluid loss from calipers, cylinders or the master - any ideas??? It first decent trip for a few months.

My thought was old / contaminated fluid rather than a mechanical problem - any ideas appreciated - thanks B

 

Give it some time , it will go back to normal. . Run new fluid through it all if it doesn't .

 

Rusted up front pads. My bus had this symptom. Stamping on the pedal shifted the rust eventually..
Pull the pads out both sides can be hard work !!. File the rust off the calipers where the pads were rusted in and put them back and be amazed.

 

It could be an internal leak in the master cylinder; no fluid loss but it passes the seals. Press the pedal hard, does it very slowly sink?

 

Cheers guys - will take out the front pads as a start and see what they are like, it has sat for sometime so worth a shot! Hadn't thought about internal seals, I assume if that is the case as I press the pedal I should see some disturbance in the fluid if the top is off the master?

 

No disturbance in the reservoir when the pedal is pressed down hard so I assume the seals are okay ? I'll bleed and check the pads sticking at the front and see if that does anything!!

 

air in system? old fluid? change the fluid. have you had a sticky caliper at all some point and boiled the fluid, did you check that you haven't got that issue and the fluid is boiling up. easy to tell as that wheel will be hot!

 

That's interesting, did have a warm rear wheel, the handbrake was over adjusted and rubbed when used a few weeks ago - seems to me that a flush through with new fluid is defiantly required

 

warm wouldn't do it but you never know. New fluid cant hurt!

 

Had similar on my mg last summer. Foot went to the floor, no leaks on wheels and a full m/c res !!!. But when pushing the peddle down I could hear a swish noise from the m/c, which points to seal gone in m/c. New m/c cured this but the worst part was bleeding the back brakes and on a recommendation tried 'gravity bleeding' which is easy by just puting a tube over the nipple, undoing the bleed nipple half a turn and just let the fluid flow out on its own, and keep a eye on level in m/c. Tighten up when done and 'jobs done'

 

Rear brakes need adjusting ?

 

Leak on the rear brake bias valve thingy
Mine was wheezing

 

I had this. Easy fix actually.