I have a 1999 VW Jetta TDI (diesel). Recently (just over the past couple weeks) my brakes have begun doing something weird: they usually act just fine, but randomly (I can’t find a pattern) the pedal gets very hard to push. The brakes still grab, but the amount of pressure I have to use is at least triple what I normally have to use.
The pads are relatively new (less than 20k miles) and I’m generally not very demanding on the brakes. Most of my driving is highway, but I do some city driving as well.
Any idea?
IMHO, the brake booster is intermittently failing, causing the hard pedal. How does your TDI brake booster work, since diesels don’t produce vacuum? Does it work with hydraulic pressure? Does the TDI use an auxillary vacuum pump? However the booster gets power is probably the part that is failing.