1990/09/01 Caterpillar

When replacing fluid level switches, temperature switches, temperature senders, etc. which are casegrounded through the pipe threads (single wire output) DO NOT use teflon tape to seal the threads. Use pipe sealant such as 5P3413 Pipe Sealant, which contains teflon, to seal liquids and gases up to 149 °C (300°F). This only applies to pipe thread type devices. It does not apply to O-ring type devices which need no sealant.

Teflon tape may insulate the electrical connection between the switch (sender) threads and the block or tank causing the device to work incorrectly. In hydraulic applications, teflon tape can also become lodged in valves causing incorrect operation of hydraulic components.