What wrench is required to change thermostat on 1991 Ford F150?

A 1991 Ford F-150 typically requires a socket wrench, most commonly a 7/16 inch or 9/16 inch to remove the thermostat housing bolts. However, this can vary slightly depending on the engine.

It's crucial to verify which size is needed for your specific truck's engine. Consult your owner's manual or a repair manual specific to your year, make, and model F-150 for definitive information. You might also find this information online through forums dedicated to Ford F-150s.

Simply assuming one size could lead to stripping a bolt or using the wrong tool. Always double-check before starting the job.