A recent problem in our Ask a Mechanic forums involves an older vehicle with high mileage. In her 1996 Mercury Cougar with over 200,000 miles, user Katy was having a clicking noise at 45+ miles per hour. Usually just a single click, often accompanied by an engine miss or hesitation.
The Cougar itself came with a six and an eight-cylinder engine. Katy believes hers is a V8, but in either case, the problem is almost assuredly the same problem. Big Block 409 asked the key question to determine that: