Hi, I have an e36 325i with an s50 engine which I'm preparing as a drift car. After playing with the car at high rpms, I heard a pop from the engine bay. I immediately turned the car off and gave it a visual inspection. There was no liquids leaking and the car still had oil and coolant. A few days later, I let the car idle for a bit to see if I could find the problem but the car stayed at proper temperature. Another few days past and I decided to take it out. After a few blocks, the car started overheating again. Thinking it was the water pump, I took it off today but the impeller was still intact.. Any ideas what could be causing the overheating? There was no white smoke out of the tailpipes when the pop happened. I filled the coolant not too long before taking the car out before the incident. Could I have overfilled it and improperly bled the system? Any help would be greatly appreciated.