Sierra 18-3568
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Sierra 18-3568 Product Description
Sierra 18-3568 Thermostat Kit - 160° Professional Cooling System Component
Maintain optimal engine operating temperature with the Sierra 18-3568 Thermostat Kit. Designed for MerCruiser GM V-6 and V-8 engines with closed cooling systems, this complete 160-degree thermostat kit ensures precise temperature regulation for peak performance and engine protection.
Key Features & Benefits
- 160-Degree Rating - Optimal opening temperature for MerCruiser closed cooling systems
- Complete Kit - Includes thermostat and seal for comprehensive replacement
- OEM Replacement Quality - Direct replacement for MerCruiser 99155T1
- Marine-Grade Construction - Built to withstand harsh marine environments and temperature extremes
- Closed Cooling Specific - Engineered for GM V-6 & V-8 closed cooling systems (1998 & newer)
- Precision Temperature Control - Maintains optimal engine operating temperature for performance and longevity
Technical Specifications
| Manufacturer: | Sierra Engine Parts |
| Part Number: | 18-3568 |
| UPC Code: | 808282112783 |
| Opening Temperature: | 160°F (71°C) |
| System Type: | Closed Cooling Systems |
| Kit Weight: | 1.00 lbs |
Kit Contents
- 18-3555 Thermostat - 160-degree marine thermostat
- 18-1508 Thermostat Seal - Precision-fit gasket for leak-free installation
Engine Compatibility
Direct Replacement For:
- MerCruiser 99155T1
- GLM 13421
Compatible Engine Systems:
- GM V-6 & V-8 engines with closed cooling (1998 & newer)
- MerCruiser 454, 340HP closed cooling systems
- MerCruiser 5.7L-7.4L engines
- 5.7MIE (1998-2001)
- MX6.2LMPI (2000-2001)
- 454 Horizon MIE (1998-2001)
- 502 Mag. MPI (1998-2001)
Installation & Service
Installation Guidelines:
- Allow engine to cool completely before beginning work
- Drain cooling system to below thermostat housing level
- Remove thermostat housing and old thermostat
- Clean all gasket surfaces thoroughly
- Install new thermostat with spring facing toward engine block
- Use new gasket/seal provided in kit
- Refill cooling system with appropriate coolant mixture
- Bleed air from system and test for proper operation
Why Choose Sierra Thermostat Kits?
Sierra Marine has been manufacturing premium cooling system components for over 40 years. Their thermostat kits are engineered to meet or exceed OEM specifications, using advanced materials that provide reliable operation in demanding marine environments. Each kit includes precision-manufactured components for complete, leak-free installation.
Signs You Need This Thermostat Kit
- Engine overheating or running too cool
- Inconsistent operating temperature
- Coolant leaks around thermostat housing
- Thermostat stuck open or closed
- Regular maintenance interval replacement
- Poor heater performance (running too cool)
Cooling System Function
The thermostat plays a critical role in engine cooling:
- Temperature Regulation - Opens at 160°F to allow coolant circulation
- Warm-Up Efficiency - Stays closed during startup for faster warm-up
- Engine Protection - Prevents overheating by controlling coolant flow
- Optimal Performance - Maintains ideal operating temperature for efficiency
- Emissions Control - Helps engine reach proper operating temperature quickly
Maintenance Recommendations
Service Guidelines:
- Replace thermostat every 3-5 years or per manufacturer recommendations
- Inspect during annual cooling system service
- Replace if engine overheating or running too cool occurs
- Always replace gasket/seal when installing new thermostat
- Test operation after installation by monitoring operating temperature
- Use proper coolant mixture as specified by manufacturer
Frequently Asked Questions
What temperature rating do I need for my MerCruiser engine?
This 160-degree thermostat is designed for GM V-6 & V-8 engines with closed cooling systems from 1998 and newer. Verify your specific engine requirements before ordering.
Can I reuse the old thermostat gasket?
No, always use the new seal provided in the kit. Reusing old gaskets can result in coolant leaks and improper thermostat operation.
How do I know if my thermostat is working properly?
Monitor engine operating temperature. The thermostat should open around 160°F, allowing the temperature gauge to stabilize at normal operating range.
What happens if I install the thermostat backwards?
Installing the thermostat with the spring facing the wrong direction can cause overheating or prevent proper coolant circulation. The spring side faces toward the engine block.
How often should I replace my marine thermostat?
Replace thermostats every 3-5 years as preventive maintenance, or immediately if temperature regulation problems occur. Always replace during major cooling system service.
Warranty & Support
Sierra Marine Parts are backed by manufacturer warranty against defects in materials and workmanship. Professional installation and proper coolant maintenance ensure optimal performance and longevity.
Save $2 when you buy the Sierra 18-3568 for only $21 from NVN Marine! Same day shipping before 3pm.
Sierra 18-3568 Technical Specifications
| Type: | |
|---|---|
| Vendor: |
Sierra Engine Parts |
| Weight: |
0.17 lb |
Sierra 18-3568 User Reviews
Sierra 18-3568 Shipping & Return
| Shipping Weight: |
0.17 lb |
|---|---|
| Box Sizes: |
2.00 (h) x 6.00 (w) x 7.00 (l) |
| Cubic Feet: |
84.0 |
| Returnable: |
Yes |
For detailed shipping policy please check our Shipping Policy and you can find our Return and Refund Policy here.