They are for bleeding the master cylinder. Do it as part of the normal brake bleeding process to purge any air left there. Often gets missed and is often the cause of spongey peddle
This is an older thread, you may not receive a response, and could
be reviving an old thread. Please consider creating a new thread.
Volkswagen Mark IV Forum
A forum community dedicated to Volkswagen Mark 4 owners and enthusiasts in the UK. Come join the discussion about performance, modifications, classifieds, troubleshooting, maintenance, and more for the Golf, Bora, Jetta, Touran, and Scirocco!