Home › Forums › Stay Dirty Lounge › Service and Repair Questions Answered Here › Clogged heater core be respnsible for overheating? › Re: Clogged heater core be respnsible for overheating? November 4, 2012 at 10:05 pm #474119 Patricia ShortParticipant I will stop by the parts store today to grab a block testing kit. I still don’t know where the bleeder is though. Am I going to have to drain the coolant since it so filled up in the reservoir?