Gates 34299 Heavy-Duty Engine Coolant Thermostat - 190°F Bottom By-Pass

The Gates 34299 Green Stripe Heavy-Duty Engine Coolant Thermostat is engineered to withstand the extreme noise, vibration, and harshness conditions found in heavy-duty truck, bus, tractor, and heavy equipment applications. Designed as a thermostat only (housing not included), this 190°F bottom by-pass thermostat features a temperature-sensitive heat motor for consistent valve response, delivering smooth performance and precise engine temperature control. With a start-to-open temperature of 190°F (88°C) and a bottom by-pass design, it provides reliable coolant flow management to protect demanding diesel and commercial engines.

Key Features:

• Heavy-gauge brass and stainless steel construction for superior corrosion resistance
• Factory-calibrated for accurate opening and closing regardless of pressure changes
• Temperature-sensitive heat motor ensures consistent valve response and precise engine cooling
• Jiggle pin (weep hole) with check valve for effective air venting — equivalent to original equipment performance
• Bottom by-pass design with sealing flange O.D. of 2.125 in., bypass flange diameter of 1.345 in., and overall height of 2.04 in.
• Start-to-open temperature: 190°F (88°C)
• Materials: stainless steel and copper

The Gates Green Stripe Heavy-Duty series is purpose-built for the rigors of commercial vehicle service. This thermostat fits 126 vehicle applications including select Freightliner and Business Class M2 models with Caterpillar C7 diesel engines (2004–2009). Thermostat only — housing, gasket, and seal are not included. California Proposition 65 Warning: Cancer and Reproductive Harm — www.P65Warnings.ca.gov.