with out draining my coolant system? I have a new radiator, waterpump and hoses original heater core. My coolant temp dropped 30 degrees with a radiator install, thinking that a clean heatercore might help. Currently running at 200 degrees. I don't want to drain my coolant system because it is full of new coolant.

 

Disconnect the hoses for the heater core at the engine. (you will lose some coolant.... I used corks to prevent too much loss. )

Back flush the heater core, add some CLR, or Limeaway, or similar product. Let it sit for the suggested period of time for whatever product you use. Flush the core again in both directions...... hook it all back up, top off the cooling system.

 

cool beans

 

You can use something like this to minimize any loss.