Does the Ford Expedition have a timing belt or chain?

Generally speaking, the Ford Expedition's engine will typically have a timing chain under the cover, though there are a few notable exceptions over the past few decades that have used timing belts instead. In order to be more accurate, You'll need to be more specific with Your model year and engine size. There's a very large chance, however, that You have a timing chain. Chains are often preferable to belts, since they have an estimated lifetime of 250,000 to 300,000 miles. Still, You shouldn't slouch on the maintenance because their replacement costs can greatly exceed that of their counterpart belts; sometimes running as much as $3,000 or more, depending on the damage that the failure caused.