i citrus flush mine with the thermostat off the engine and drive around a few blocks or so with the heator on or just unplug the monovalve electrical pin on top. then after the flush i rinse it with the engine at idle and revving the engine a couple of times or so with plain hose tap water, still without the thermostat and the heater still on. with the engine off, let the radiator drain and, reinstall the thermostat with the gasket and put the radiator plug back. fill with 60% g-05 and 40% distilled drinking water through the hose by the oil filter housing between the cylinder head and firewall on driver side until fluid level reaches the expansion tank. (why 60/40 mix? it's just my idea to compensate and make up fo the plain untouched water that sits at the bottom of the block without g-05.) then, reconnect the hose to the firewall, good and tight, check for leaks and you're done. then also, don't forget to plug back the monovalve electrical connection.

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'85 300D Turbo - CA Version