Fiat: 500 F, L and R (1965-75) • 500 Giardiniera (1960-77) • 126 (1972-87)
cylinder head
Carbon Monoxide (CO) Safety Screw
The air-cooled Fiat models 500 and 126 use the cooling air directly for heating. To prevent passengers from being poisoned with carbon monoxide unnoticed in the event of a defect in the cylinder head gasket, a duct directs the contaminated air out through a hollow screw with a whistling sound. This vent screw has a double function as a fastening element for the thermostat housing. Unfortunately, in many cars the hollow screw is replaced with a standard M8 bolt. In the event of damage to the cylinder head gasket, this is life-threatening for the driver and passengers!
Make sure that your vehicle is fitted with the original CO safety screw.