Part Number: 551004
Indmar 551004 Thermostat Gasket
Ensure a proper seal and dependable cooling system performance with the Indmar 551004 Thermostat Gasket. Designed as a genuine OEM replacement, this gasket creates a secure seal between the thermostat housing and engine components to help prevent coolant leaks and maintain stable operating temperatures.
Whenever a thermostat is replaced or serviced, installing a new gasket is essential for proper sealing. Reusing an old gasket can lead to coolant seepage, air leaks, or uneven sealing surfaces that may affect cooling system efficiency. The Indmar 551004 gasket is engineered to provide the correct fit and sealing performance for compatible marine engine applications.
Manufactured to Indmar factory specifications, this marine-grade gasket is built to withstand heat, coolant exposure, and constant engine vibration in demanding boating environments. Designed as a direct replacement, it helps simplify maintenance and restore factory-level sealing performance.
Common Engine Fitments
The Indmar 551004 thermostat gasket is commonly used on GM-based Indmar marine engines, including:
- Indmar Assault 5.7L
- Indmar Monsoon 325
- Indmar Monsoon 340
- Indmar Assault 325
- Indmar 5.0L MPI
- Indmar 5.7L MPI
- Select Indmar 6.0L engine configurations
These engines are frequently found in:
- Supra Launch series
- Supra Sunsport and 22SSV models
- Moomba Mobius LSV
- Moomba Outback and Mojo
- Malibu Wakesetter models with Indmar engines
- MasterCraft boats equipped with Indmar power packages
The 551004 gasket is typically used during thermostat replacement and cooling system service on freshwater and closed-cooling engine configurations.
Fitment may vary depending on engine serial number and thermostat housing design, so confirming compatibility with part number 551004 before ordering is recommended.
Key Features
- Genuine Indmar OEM thermostat gasket
- Provides a reliable seal for thermostat housing assemblies
- Helps prevent coolant leaks and cooling system pressure loss
- Designed for GM-based Indmar marine engines
- Marine-grade material built for durability
- Direct-fit replacement for straightforward installation
Why Replace a Thermostat Gasket?
Old gaskets can compress, crack, or lose sealing ability over time due to repeated heat cycles and coolant exposure. Installing a new gasket during thermostat service helps maintain proper cooling system pressure and prevents leaks that could lead to overheating issues.
If you’re servicing an Indmar-powered wake boat or ski boat, the 551004 thermostat gasket delivers the OEM-quality fit and dependable sealing performance your cooling system depends on.