The $27 infrared thermometer saved my butt on a 6.0 Power Stroke
Back when we had paper repair orders and no scan tool for everything, you learned to feel heat with your hand. I picked up a cheap $27 infrared thermometer at a tool tent in Louisville a while back, mostly as a toy, but it caught a sticking thermostat on a customer's 6.0 Power Stroke before it turned into a head gasket job. Now the young guys laugh at it until I point it at an exhaust manifold and show them which cylinder is cold. What is your go-to cheap tool that ended up earning its keep?