Had my heater core replaced 2 yrs ago in my little S10 Chevy Blazer along with a new readiator, fan belt, all new coolant hoses and new u-joints in the rear drive shaft. Cost me $2000.00. Well this summer I flushed out the cooling system since it had turned the coolant rusty. Well we took it on a long trip one day and the pump developed a leak and the engine ran hotter than normal. Anyway we made it home but the overheating caused a lot of rust to break loose and of course it clogged up the heater core. I decided to soak the core with some Coke A Cola. It sure broke it loose. I also took the heater hoses off and beat them on the concrete floor. A lot of rust was stuck to the walls of the hoses like cholesterol. I've ordered a strainer to put inline of the supply hose to the heater core to prevent this from happening again.