128275-91340 Temperature Sensor for Yanmar 1GM 1GM10 2GM20 2GM 3GM30 3HM 3HM35 | JLM Marine

Temperature Sensor for Yanmar 1GM 1GM10 2GM20 2GM 3GM30 3HM 3HM35

This 65°C temperature thermoswitch sensor is engineered for Yanmar marine diesel engines across the 1GM, 2GM, and 3GM series. Designed to monitor coolant temperature and trigger warning systems, this sensor ensures reliable engine protection and performance in demanding marine environments.

Direct replacement for OEM part number 128275-91340. Compatible with a wide range of Yanmar 1-cylinder, 2-cylinder, and 3-cylinder marine diesel engines, providing critical temperature monitoring for your vessel's power plant.

• Factory-calibrated at 65°C activation temperature
• Direct bolt-in replacement for original equipment
• Essential for engine overheat protection systems

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

Your purchase includes:

• 1 × 65°C Temperature Thermoswitch Sensor

Installation Guide

1. Allow the engine to cool completely before beginning work. Verify you have the correct replacement sensor by comparing it to the original part.
2. Locate the temperature sensor on your Yanmar engine block (typically mounted on the cylinder head or thermostat housing). Disconnect the electrical connector from the old sensor.
3. Using an appropriate wrench or socket, carefully unscrew the old temperature sensor in a counterclockwise direction. Be prepared for minor coolant seepage.
4. Clean the sensor mounting threads on the engine block using a wire brush or clean cloth. Inspect the threads for damage.
5. Apply a small amount of thread sealant (appropriate for coolant contact) to the new sensor's threads if required by your engine manufacturer. Do not over-apply.
6. Hand-thread the new sensor into the mounting hole clockwise, ensuring proper alignment to avoid cross-threading. Tighten to the manufacturer's specified torque (typically 10–15 N·m).
7. Reconnect the electrical connector to the new sensor, ensuring a firm, secure connection. Check that the connector lock engages properly.
8. Refill the cooling system with the appropriate coolant mixture to the correct level. Bleed air from the system according to your engine manual.
9. Start the engine and monitor for leaks around the sensor. Allow the engine to reach normal operating temperature while observing the temperature gauge.
10. Verify that the overheat warning system activates correctly (consult your engine manual for testing procedures). Shut down and recheck coolant level after the engine cools.

Troubleshooting & FAQ

Q: How do I confirm this sensor fits my Yanmar engine?
A: Cross-reference your engine model with the compatibility table above. The sensor fits 1GM, 1GM10, 2GM, 2GM20, 3GM30, 3HM, and 3HM35 models. Verify your original part number is 128275-91340 for certainty.

Q: What are the signs that my temperature sensor needs replacement?
A: Common failure symptoms include an inoperative temperature gauge, constant overheat alarm activation, or no alarm when the engine is genuinely overheating. Coolant leakage around the sensor base also indicates replacement is needed.

Q: How often should I replace the temperature sensor?
A: Temperature sensors typically last several years under normal operating conditions. Replace immediately if you experience erratic gauge readings, warning light malfunctions, or visible corrosion. Inspect annually during routine maintenance.

Q: Can I install this sensor without draining the entire cooling system?
A: In most cases, yes. The sensor location is typically above the waterline when the engine is level, so you'll only lose a small amount of coolant during removal. Have a catch pan ready and top off the system afterward.

Q: What's the difference between OEM and this aftermarket sensor?
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.