Calorstat TH5111.75J Engine Coolant Thermostat

Engine Coolant Thermostat for BMW Applications

Calorstat TH5111.75J is a standard engine coolant thermostat built for precise temperature control in BMW cooling systems. It opens at 167.0°F and includes an O-ring seal for a direct-fit service replacement on supported BMW 325i, 535i, 735i, and related models.

Key Features

• Standard engine coolant thermostat for cooling system temperature regulation
• Start to open temperature: 167.0°F
• Gasket or seal included with rubber O-ring seal
• Sealing flange outside diameter: 2.63 in.
• Valve-seat diameter: 67.0 mm
• By-pass valve diameter: 35.0 mm
• Calorstat TH5111.75J part number for catalog matching and service lookup

Detailed Description

This Calorstat thermostat is specified for BMW cooling system service where stable coolant flow and temperature control are required. The TH5111.75J uses a standard design with an included rubber O-ring seal, a 1 in. height between flanges, and measured dimensions that support accurate housing fitment. Vernet is an OE supplier to BMW, and this thermostat is listed for a wide range of BMW inline-six applications including the 325i, 535i, 735i, 735iL, 325is, 325iX, 525i, 635CSi, 528e, 535is, 325e, and 325es.

This part cross-references Motorad 273-167 for the same application. The TH5111.75J is also referenced against part numbers 4235.75 and VT226.75 for catalog comparison.

What It Helps Address

• Engine running too cool or too warm due to thermostat wear
• Delayed coolant circulation during warm-up
• Temperature fluctuation in BMW cooling systems
• Coolant seepage at the thermostat seal area
• Service replacement for aging thermostat housings and seals

Installation Notes and Tips

Verify housing dimensions, bypass valve diameter, and valve-seat diameter before installation. Replace the thermostat with the included O-ring seal during service, and inspect the mating surfaces for corrosion, debris, or old seal material. Confirm the application by year, make, and model before ordering; this part is listed for 1982-1993 BMW 325e, 325es, 325i, 325is, 325iX, 525i, 528e, 535i, 535is, 635CSi, 735i, and 735iL applications.

Quality Assurance

Calorstat and Vernet are established names in engine cooling components, and Vernet is identified as an OE supplier to BMW for this application family. Part number TH5111.75J is cataloged to OE-style specifications for BMW thermostat service.