Calorstat TH1528.80J Engine Coolant Thermostat

BMW Engine Coolant Thermostat TH1528.80J

Calorstat TH1528.80J is a standard engine coolant thermostat for select BMW applications, including 1975-1978 BMW 530i, 1979-1981 BMW 528i, 1983-1984 BMW 533i, and 1985 BMW 535i. It is built with a gasket O-ring seal and opens at 176.0 degrees to help regulate coolant flow at the specified operating temperature.

Key Features

• Part number TH1528.80J for direct catalog identification
• Standard thermostat design for engine cooling system service
• Start to open temperature: 176.0 degrees
• Gasket included with rubber + paper seal material
• Valve-seat diameter: 67.0
• By-pass valve diameter: 29.0
• Sealing flange outside diameter: 2.63
• Height between flanges: 1.37
• Height shoulder: 2.5
• Height, by-pass side: 35.0

Detailed Description

This Calorstat engine coolant thermostat is specified for BMW cooling system applications where accurate coolant temperature control is required. The TH1528.80J uses a gasket O-ring seal and a standard thermostat layout, with dimensions that include a 67.0 valve-seat diameter and 29.0 by-pass valve diameter for proper housing fitment. Calorstat TH1528.80J is listed for BMW 530i, BMW 528i, BMW 533i, and BMW 535i applications, and Vernet is identified as an OE supplier to BMW in the fitment notes.

This part cross-references Motorad 246-174 for the same application.

What It Is Used For

• Replacing a thermostat that is stuck open and causing slow warm-up
• Replacing a thermostat that is stuck closed and contributing to overheating
• Restoring stable coolant temperature control in BMW cooling systems
• Addressing temperature fluctuation caused by worn sealing surfaces or seal leakage
• Servicing a thermostat housing during cooling system maintenance

Installation Notes and Tips

Verify housing dimensions, seal condition, and coolant system cleanliness before installation. Match the thermostat orientation and by-pass side dimensions to the original part, and use the included gasket or O-ring seal during assembly. After installation, refill and bleed the cooling system according to BMW service procedures to remove trapped air and confirm normal operating temperature.

Quality Assurance

Calorstat is associated with OE supply for BMW applications, and this thermostat is cataloged with application-specific dimensions and seal details for accurate replacement selection.