Master cylinder leakage

same problem installed one of these View attachment 1715791775 seems to works so far some were installed on max wedge cars// I believe //but my exhaust manifold is right under my MC // my infrared thermometer showed a significant temp reduction///cooking your seals most likely
Don't think that's it. Last one bench bled, left pressurized for 18 hours with tie raps, no leaks, installed on car. Leaks at spare port. 1/4 pipe plug. No leak at brake line. Perplexed.