How do you change the timing chain in a 2003 Ford Expedition?

To change the timing chain in a 2003 Ford Expedition, first disconnect the battery and remove any components obstructing access to the engine, including the intake manifold and front cover. Next, align the timing marks on the crankshaft and camshaft, then remove the old timing chain and sprockets. Install the new timing chain, ensuring the timing marks are correctly aligned, and reassemble the engine by reversing the disassembly steps. Finally, reconnect the battery and start the engine to check for proper operation.