Sometimes when I brake I hear a thump that I can hear, and feel through the brake. I have a Suzuki SX4, automatic transmission. It doesn't matter if I brake quickly or slowly and it is just one "thump" that lasts a second. My mechanic said I need to have timing valve cover replaced, said I have a leak. He hasn't retrned my calls where I wanted to ask about the thumping noise. The mechanic does not know about the thump yet, may not have felt it since it is sometimes. thanks for any answers.