I'm not expert but if its all 4 brakes getting hot you'd think it has to point to something at the 'master' end of the setup i.e. master cylinder, brake pedal or something before the 4-way hydraulic split. Is it possible to observe the actuating rod for the master cylinder piston to check if it is ...

It sounds like your brake calipers could do with overhauling. Maybe the pistons are sticking and/or the sliders have seized. I've had it happen to me when a boot has split and let water in.
Brakes got sorted a couple of weeks ago,fitted second hand master cylinder from nipon spares derby,thanks ...

Having had my Bongo for 3 months - I have noticed on occasion that the brake pedal position has altered. In recent weeks I have felt that the brakes have been binding but then releasing again the other day I noticed that all 4 brake discs were piping hot. Has anyone experienced this sort of problem ...