magnum guru

The Magnum GURU Plug is a higher discharge capacity version of the standard GURU Plug. The Magnum GURU Plug is a self-operating thermostatic drain valve that responds to engine coolant temperature and will pop open and drain when coolant reaches the setpoint (35°F or 40°F). This provides almost a full 1.2in bore to rapidly drain a locomotive before freeze damage can occur.

Resetting and rearming the Magnum GURU Plug is easily accomplished by simply reheating the cartridge and utilising the slotted actuator feature with the GURU Flag and Clip tool. This feature prevents the GURU Plug from triggering open again while refilling the cooling system with cold water.


  • Drains twice as fast as the standard GURU Plug
  • Will not trip or dump while locomotive is running
  • Straight SAE threads and O-ring seals provide for easy field maintenance and testing
  • Easy installation
  • Completely mechanical, no electrical or air connections
  • Not affected by air flow or air temperature surrounding valve, releases only when cooling water reaches setpoint
  • Easy system refill
  • Models available to convert existing freeze protection
  • Slotted actuator feature prevents nuisance dumps when refilling cooling system with cold water
  • Unit automatically rearms after filling and reheating

Design features:

  • Actuator sensing surface is the only wetted part
  • Design excludes cooling water chemicals and other debris from moving parts
  • Long service life: All moving parts are stainless steel
  • Available in modified 1-1/4in NPT tee or flanged tee body styles
  • Paint mask minimises accidental paint-ins
  • Knob on cartridge for easy installation and removal even in awkward locations


  • Locomotive engine and compressor set cooling systems
  • Stand-by diesel heating circulators
  • Back-up protection in event of shutdown
  • Hot water cab heater lines
  • On-board tanks and piping