Sounds more like a sticky caliper getting way too hot.
No, there isn't supposed to be a knotted line in there, I'd guess it is distorted from the heat.
You will need to check out all the plastic vac lines in the area, get the brakes checked (you may have a "one-way-valve" in the brake line from separated lining -- works fine to transmit pressure to the caliper, but won't let go!
Replace anything damaged by heat, and you will need to get the fender repainted -- if the paint is discolored, bet on it failing soon. Get the bottom side undercoated at the same time to prevent rust.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!