I just was driving home from school, and there is this horrible noise. The hood of the car is slightly open, cause the PO put blocks under the hood hinges to aid in cooling before he put the new bigger rad. in. It started to rain, and all of a sudden there was this horrible noise. It sounds kinda like super loud exhaust, almost a putting noise. COULD THIS BE AN ENGINE KNOCK?!?!?! it speeds up with engine speed, but she'll start up after i turned her off (once). I towed her to our school parking lot and thats where she sit now, what should i do?! I was thinking maybe the exhaust man. cracked or something cause of cool water getting in? She does have an air cleaner, and the opening was dry, so i dont think any water could have gotten in, the oil is at a exceptable level, and i just drove her 120 miles home yesterday, please help my new baby! by the way, 350, with a 400 cam=383 chevy