Price: Contact us for purchase info: (877) 379-8258

SKU: 35°F: 487-04-88 40°F: 487-04-87

Product Description

GURU® DL 2.1-35
GURU® DL 2.1-40

Click here for GURU® DL2.1 product sheet
Click here for GURU® DL 2.1 Installation and Maintenance Instructions
Click Here for GURU® Cap color table

Standard setpoint temperature of 35°F or 40°F


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


The GURU® DL2.1 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 Actuator sensing surface is the only wetted part

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

GURU® DL2.1 valves are covered by a one-year warranty