(T) Punto brakes suddently binding

Punto 60SX 1996. When driving brake pedal suddently gets very hard (like there are no vacuum assistance) and the front brakes binds and gets very hot. Then I can just leave the car for a while and everything is okay again. This comes and go with no real pattern and I cannot figure out the root cause. Can anyone help?

Thanks

I think the most likely cause is the valve within the vacuum servo. My theory is that it is sticking open, so the engine cannot provide sufficient vacuum due to the leak, leading to the hard pedal pressure. And, if this valve is slightly open, it will put slight pressure on the master cylinder, leading to binding of the brakes.

Thanks for your quick reply :-) Is there a way to analyze/determine this before buying a new vacuum servo unit?

I suppose the only way to tes this would be to disconnect the vacuum supply hose from the servo, and drive around carefully for a bit to see if the binding happens (clearly the stiff pedal will be evident at all times). This is best done on a private bit of road.

Thanks again. I'll try this out one of the next days, and let you know the result.

Try this too

With the engine & Ignition off, apply braking pressure to the brake pedal & hold the pedal in that position, then start the engine & the pedal should sink slightly.

If it does the servo is working, if not the servo is not functioning correctly.