Calorstat TH5973.80J Engine Coolant Thermostat

Engine Coolant Thermostat for Volkswagen Applications

The Calorstat TH5973.80J engine coolant thermostat is a standard replacement thermostat for select Volkswagen cooling systems. It is built with an O-ring seal, rubber valve, and jiggle pin weep hole to support consistent coolant flow control and easier air bleeding during service.

Compatible With 1992-2005 Volkswagen Corrado, Passat, Golf, Jetta, and EuroVan applications, this thermostat is specified with a 176.0 degree start-to-open temperature and OE-style dimensions for the sealing flange, valve seat, and bypass side.

Key Features

• Calorstat TH5973.80J engine coolant thermostat
• Standard thermostat design for cooling system temperature regulation
• Start to open temperature: 176.0 degrees
• Gasket or seal included; O-ring seal type with rubber seal material
• Jiggle pin weep hole for air purge during coolant service
• Rubber valve construction
• By-pass valve diameter: 29.0 mm
• Valve-seat diameter: 67.0 mm
• Sealing flange outside diameter: 2.63 in.

Detailed Description

The TH5973.80J thermostat is engineered for Volkswagen cooling system service where accurate coolant temperature control matters. Its 176.0 degree opening point helps regulate engine operating temperature, while the included O-ring seal and rubber sealing material support a secure housing interface. The jiggle pin weep hole can assist with trapped-air relief during filling and bleeding, and the bypass valve design supports proper coolant routing as the thermostat cycles. This part cross-references Gates 12192 for the same application.

Use this thermostat when replacing a worn or sticking unit on Volkswagen Golf, Jetta, EuroVan, Corrado, or Passat models covered by the listed fitment. The Calorstat TH5973.80J is a direct-fit cooling system service part for vehicles that require the specified dimensions and temperature rating.

Common Problems This Part Can Address

• Engine running too cool or taking too long to reach operating temperature
• Temperature fluctuations caused by a thermostat that opens inconsistently
• Coolant flow issues related to a sticking thermostat valve
• Air pockets in the cooling system after thermostat service
• Leaks at the thermostat seal or housing interface

Installation Notes and Tips

Install the thermostat with the correct orientation for the housing and coolant flow path. Inspect the mating surfaces before assembly and replace any damaged seal surfaces as needed. Fill and bleed the cooling system carefully so the jiggle pin weep hole can help release trapped air. Verify the cooling system reaches normal operating temperature after installation and check for leaks at the seal area.

Quality Assurance

Calorstat is listed as an OE supplier to Volkswagen, and this thermostat follows OE-style fitment and dimensional specifications for the covered applications. Confirm the part number TH5973.80J against the vehicle’s original thermostat specification before installation.

Vehicle Fitment

• Fits 1995-2005 Volkswagen Golf, N/A
• Fits 1994-2004 Volkswagen Jetta, N/A
• Fits 1999-2002 Volkswagen EuroVan, N/A
• Fits 1997 Volkswagen EuroVan, N/A
• Fits 1993-1997 Volkswagen Passat, N/A
• Fits 1992-1995 Volkswagen Corrado, N/A