Magnum GURU®


The Magnum GURU® Plug has a higher discharge capacity than the standard GURU® Plug. This thermostatic drain valve responds to the engine coolant temperature and will pop open to rapidly drain the system before freeze damage can occur when the coolant reaches the valve’s set point (35°F or 40°F) providing almost a full 1.2-inch bore.

Designed with 1-7/8” UN—2B Straight Threads and an O-ring, the Magnum Plug eliminates the need for Teflon tape and pipe dope, making maintenance and replacement a breeze.

Resetting and rearming the GURU® Plug is easily accomplished by simply reheating the cartridge and reinserting it into the hex nut. We recommend utilizing our GURU® Flag and Clip or GURU® Flag and Key tool during the refill process to prevent the GURU® Plug from snapping open again from the cold resupply water.

Magnum GURU® Plug

Typical Applications

The self-actuating Magnum GURU® Plug is used to prevent freeze damage in diesel locomotive engines, compressor set cooling systems, stand-by diesel heating circulators, hot water cab heater lines, and onboard tanks and piping.

Design Features

  • Exclusive self-actuating Thermoloid® blend paraffin wax actuator
  • Thermal actuator 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 1-1/4” NPT tee or flanged tee body styles
  • Straight SAE threads and O-ring seals provide easy field maintenance & testing
  • Paint mask minimizes accidental paint-ins
  • Knob on cartridge for easy installation and removal even in hard-to-reach locations


  • Self-operating – no external power source required
  • Drains twice as fast as the GURU® DL2.1
  • Will not trip or dump while the locomotive is running
  • Not affected by airflow or air temperature surrounding valve
  • Easy installation
  • Easy system refill
  • Slotted actuator feature prevents nuisance dumps when refilling the cooling system
  • Valve automatically rearms after filling and reheating
  • Optional domed anti-tamper cap eliminates ability to tamper with the valve resetting stem