Calorstat TH1439.80J Engine Coolant Thermostat

Engine Coolant Thermostat for Porsche and Volkswagen

Calorstat TH1439.80J is a standard OEM-grade engine coolant thermostat built for precise coolant flow control and stable operating temperature. It opens at 176°F (80°C) and includes a gasket O-ring seal for a direct replacement on select Porsche 944, Porsche 928, Porsche 968, and Volkswagen Jetta applications.

Key Features

• OEM-grade standard thermostat for engine cooling system service
• Start-to-open temperature: 176°F / 80°C
• Gasket or seal included for installation
• Seal type: gasket O-ring
• Rubber + paper seal material
• Sealing flange outside diameter: 2.12 in.
• Height between flanges: 1.24 in.
• By-pass valve diameter: 35.0 mm
• Valve-seat diameter: 53.9 mm

Detailed Description

Calorstat TH1439.80J is an engine coolant thermostat designed to regulate coolant circulation at the specified opening temperature, helping the engine reach and maintain proper operating temperature. The OEM-grade construction and included seal support a direct-fit service replacement for cooling system maintenance on 1991 Porsche 944, 1992-1995 Porsche 968, 1993-1994 Porsche 928, and 1980 Volkswagen Jetta applications. This part cross-references Bosch 13378 for the same application.

What It Helps Address

• Engine running too cool or taking too long to warm up
• Temperature fluctuations caused by a worn thermostat
• Coolant flow control issues in the thermostat housing circuit
• Cooling system service needs on Porsche 944, Porsche 928, and Porsche 968
• Replacement of an aging thermostat during preventive maintenance

Installation Notes and Tips

Verify the thermostat opening temperature and physical dimensions before installation. Clean the housing sealing surfaces thoroughly and replace the thermostat with the included gasket O-ring seal. Confirm correct orientation and bypass-valve alignment during assembly, then refill and bleed the cooling system according to the vehicle service procedure. Fits 1991 Porsche 944, N/A. Fits 1992-1995 Porsche 968, N/A. Fits 1993-1994 Porsche 928, N/A. Fits 1980 Volkswagen Jetta, N/A.

Quality Assurance

Calorstat is listed as an OE supplier to Volkswagen for this application, and the TH1439.80J follows OEM-grade specifications for fit and temperature control.