This weekend is going to be ok for working on cars. I have installed my new water pump, but the radiator is not in yet (it is brand new). My block and heater core are full of oil-contaminated coolant, so I want to really douche the whole cooling system.

When I had my om617, I removed the thermostat and replaced the thermostat cover and hooked up a hose to flush the system. Then I ran the engine with Shout for about 20 minutes, then let it cool and flushed again.

Now I have this om603 - and am trying to figure out the best way to pre-wash as much as I can before installing the radiator (don't want to get it all dirty inside). If I attach the lower split radiator hose to the thermostat housing and the heater core, and connect the upper radiator hose to the block, but not the radiator, I am thinking that I can attach my garden hose to the upper radiator hose and flush fresh water through the entire system (including the heater) - am I imagining things? I'm not sure how to get the heater core clean without running the engine (it's not quite ready to start, should be ready by Sunday).

Ideas, recommendations ?