18-3557 F335068 Thermostat 143° for Johnson Evinrude OMC Chrysler Force Mercruiser Volvo Penta | JLM Marine

Thermostat 143° for Johnson Evinrude OMC Chrysler Force Mercruiser Volvo Penta

This 143° replacement thermostat is designed to fit a wide range of marine engines, including Chrysler/Force outboards (70–135 HP), Johnson/Evinrude outboards (55–75 HP), Mercruiser stern drives (4.1–4.8L 6-cylinder, 90–200 HP GM), and Volvo Penta sterndrives (3.0 GXi, 3.0 GXiC). It ensures proper engine temperature regulation for reliable performance across multiple applications.

This thermostat directly replaces OEM part numbers 18-3557, F335068, 382385, 396987, 47594, and 21148403, as well as aftermarket equivalents from GLM and Mallory. It is compatible with thermostat kits 18-3669, 18-3669D, and 18-3626.

• Fits MCM GM in-line 6-cylinder engines
• Operating temperature: 143°F
• Use with compatible thermostat kits for complete assembly

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below.

Technical Specifications

Package Contents

• 1 × Thermostat (143°)

Installation Guide

1. Allow the engine to cool completely before beginning work. Relieve any residual pressure in the cooling system.
2. Locate the thermostat housing on your engine and disconnect the upper radiator hose if necessary. Remove the housing bolts and carefully lift off the cover.
3. Remove the old thermostat and clean all gasket surfaces thoroughly to ensure a proper seal. Inspect the housing for cracks or damage.
4. Install the new 143° thermostat in the correct orientation (spring side typically faces into the engine block). Refer to your engine manual if unsure.
5. Place a new gasket (included in compatible thermostat kits 18-3669, 18-3669D, or 18-3626) onto the housing surface. Do not reuse old gaskets.
6. Reinstall the thermostat housing cover and tighten bolts evenly to the manufacturer's specified torque. Reconnect any hoses removed during disassembly.
7. Refill the cooling system with the appropriate coolant mixture for your engine. Bleed air from the system according to the service manual.
8. Start the engine and allow it to reach operating temperature while monitoring for leaks. Check coolant level and top off if needed.

Troubleshooting & FAQ

Q: How do I confirm this thermostat fits my engine?
A: Cross-reference your engine's OEM part number with the Part Number Cross-Reference table above. Verify your engine model, horsepower, and year in the Compatible Engine Models section to ensure proper fitment.

Q: Can I install this thermostat without the gasket kit?
A: While the thermostat itself is included, you will need a compatible thermostat kit (18-3669, 18-3669D, or 18-3626) that contains the gasket and seals. Reusing old gaskets can cause leaks and overheating.

Q: How often should I replace my thermostat?
A: Thermostats should be inspected annually and replaced every 2–3 years or as recommended by your engine manufacturer. Replace immediately if you notice overheating, fluctuating temperature readings, or coolant leaks.

Q: What are the signs of a failing thermostat?
A: Common symptoms include engine overheating, running colder than normal, erratic temperature gauge readings, and poor heater performance. If the thermostat sticks closed, the engine will overheat; if stuck open, it won't reach optimal operating temperature.

Q: Is this an OEM or aftermarket thermostat?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.