Description

Oil Pressure Switch – tapered thread, engine lubrication circuit.

Screws into the oil gallery – at the pump, the filter housing or the oil cooler depending on application – and monitors gallery pressure. The contacts close at low pressure to earth the warning lamp circuit and open once the pump lifts pressure past the switching threshold, so the lamp illuminates with the ignition and extinguishes shortly after the engine fires. A failed switch shows as a lamp that stays lit despite healthy oil pressure, or one that never illuminates at all.

This is the tapered-thread version: it seals on the thread form itself rather than against a separate washer, so a thread sealant suitable for oil galleries is used on fitting and the switch is tightened to the specified torque – overtightening a tapered thread is what splits an alloy housing.

A weeping switch drips oil down the side of the block, so it is worth ruling out before condemning a gasket.