Here's what I do for an engine flush. I start with a short piece of 3/4" radiator hose, a female garden hose fitting and an on-off garden hose valve. Unhook the lower radiator hose, remove the drain plug from the engine block. Unhook the upper heater hose and hook the garden hose to the fitting on the engine. Open the garden hose valve slowly, too much pressure and you can kiss the radiator and heater core good-by. Flush until clean water comes out everywhere. If no water comes out the block drain, take a piece of baling wire and start poking it around to the back and top until it starts flowing. This blockage will keep the rear of your engine from being cooled. Then put the hose down the radiator and flush away. I would not use the cleaner unless there is a lot of visible buildup in the radiator, it will probably open up a bunch of pinhole leaks.
