Re: Riser and exchanger Cleaning
If this is for a 470, then as far as the riser (exhaust elbow in the 470) goes it is filled with antifreeze, and you only need to be concerned with the water exiting the heat exchanger and flowing into the exhaust. Remove the exhaust hoses and check it. You need to make sure that the passageway is clear of any obstructions, and that the water flows freely. For the heat exchanger the book recommends removing the endcaps and cleaning the tubes with a brush, then blowing them out with air. By FAR the best thing you can do is keep the impeller in good shape. If you want to flush the engine, use automotive flush.