Guru DL 2.1

The GURU® DL 2.1 is the most widely used and proven locomotive freeze protection valve in the world. It may be thought of as an automatic freeze-out plug with one important difference: The stainless steel GURU® Cartridge releases itself from its body at a pre-set water temperature (35°F or 40°F), rather than being forced out by the tremendous pressure of expanding ice. This provides almost a full one inch bore to rapidly drain the typical locomotive before damage can occur.

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


  • Will not trip or dump while locomotive is running
  • Fully automatic, it never forgets to activate freeze protection
  • Completely mechanical, no electrical or air connections
  • Not affected by air flow or air temperature surrounding valve, releases only when cooling water reaches setpoint
  • Rapid draining
  • Easy system refill
  • Models available to convert existing freeze protection
  • Easily tested in field
  • 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
  • Long service life: All moving parts are stainless steel
  • Design excludes cooling water chemicals and other debris from moving parts
  • Easy maintenance
  • Several body styles available for various applications: 1-1/4 NPT, tee, and flanged tee
  • Paint mask minimizes accidental paint-ins
  • Knob on cartridge for easy installation and removal even in awkward locations
  • Choice of release temperatures: 35°F or 40°F


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