Calorstat TH5111.71J Engine Coolant Thermostat

Engine Coolant Thermostat for BMW 325i and 535i

Calorstat TH5111.71J is a standard engine coolant thermostat built for precise temperature control in classic BMW cooling systems. With a 160.0°F opening temperature and included O-ring seal, it supports stable coolant flow for applications such as the BMW 325i, 535i, and 735i.

Key Features

• Standard engine coolant thermostat for belt and cooling system service
• Starts to open at 160.0°F / 71°C
• Includes gasket or seal with rubber O-ring seal type
• Sealing flange outside diameter: 2.63 in.
• Valve-seat diameter: 67.0 mm
• By-pass valve diameter: 35.0 mm
• Calorstat TH5111.71J cross-references Gates 12254 and Motorad 247-160 for the same application

Detailed Description

Calorstat TH5111.71J is an engine coolant thermostat for BMW cooling system maintenance where a 71°C / 160°F opening temperature is specified. It is listed for a wide range of BMW applications, including 1987-1993 BMW 325i, 1985-1993 BMW 535i, 1985-1992 BMW 735i, and 1988-1992 BMW 735iL. The thermostat uses a standard design with an included rubber O-ring seal to support a proper seal at the housing interface. Additional fitment includes 1987-1991 BMW 325is, 1988-1991 BMW 325iX, 1989-1990 BMW 525i, 1985-1989 BMW 635CSi, 1987-1988 BMW 528e, 1982-1983 BMW 528e, 1988 BMW 535is, 1984-1987 BMW 325e, 1986-1987 BMW 325es, and 1983-1984 BMW 533i. The part number TH5111.71J is also referenced in interchange listings for OE-style replacement matching the same cooling system application.

Common Issues This Part Can Address

• Engine running too cool because the thermostat opens at the wrong temperature
• Delayed coolant circulation after warm-up
• Temperature fluctuation caused by a worn thermostat element
• Coolant seepage at the thermostat seal surface
• Cooling system service on BMW 3 Series, 5 Series, 6 Series, and 7 Series models

Installation Notes and Tips

Verify the housing style, sealing flange diameter, and opening temperature before installation. Clean the thermostat housing mating surfaces thoroughly and inspect the O-ring seat for corrosion or debris. Confirm the bypass valve and valve-seat dimensions match the original part specification for your BMW application. This thermostat is listed for N/A position fitment, so use the vehicle’s cooling system layout and service manual to confirm correct placement.

Quality Assurance

Calorstat cooling components are specified for temperature-controlled engine operation and accurate fitment by application. Use the confirmed BMW fitment data and the TH5111.71J part number to match the correct thermostat for your vehicle.