This 187 Degree LS Thermostat is the go to choice for LS builds and is designed to OEM specifications, manufactured with high quality materials, and built to withstand demanding cooling system conditions.

Its the perfect match for our WA01000LS or WA01000LT -16 LS Thermostat Housing and WA01001LS-20 LS Thermostat Housing.

Includes:

• (1) 187 LS Thermostat
• (1) Gasket / Seal

Specifications

• Temperature Rating: 187 F (86 C)
• Material: Copper & Stainless Steel
• Flange Thickness:
  • 1/16 in
  • 1 mm
• Flange Diameter:
  • 2-1/8 in
  • 37 mm
• Bypass Flange Diameter: 37 mm
• Height:
  • 2-9/16 in
  • 65 mm
• Height Between Flanges: 1-13/16 in
• Jiggle Pin / Air Relief Valve: Yes
• Seal Included: Yes
• Thermostat Included: Yes

Fitment

Designed for GM LS-based engines, including but not limited to:

• LS1
• LS2
• LS3
• LS6
• LQ4 / LQ9
• LM7 / 5.3L variants

Ideal for use with -16 and -20 AN LS thermostat housings.

Note: Always verify flange diameter and height measurements before installation in custom applications.

Tech Insight

A 187 thermostat is ideal for most LS performance builds. Constructed with a dual bridge stainless steel frame, copper casing, premium wax compound actuator, and integrated air relief valve (jiggle pin), it delivers:

• Faster temperature response
• Stable operating temperature control
• Improved engine efficiency
• Reduced warm-up time
• Reliable sealing and durability

Whether you're plumbing a full custom LS swap or upgrading your cooling system, this thermostat provides consistent, predictable performance.