Water Temperature Sender – Fits Mercury/Mercruiser 4-Cylinder, V6, V8 Engines (Replaces 97258A1)

Water Temperature Sender – Fits Mercury/Mercruiser 4-Cylinder, V6, V8 Engines (Replaces 97258A1)

This water temperature sender is a direct-fit replacement for a wide range of marine engines, including Mercury/Mercruiser sterndrive (MCM) and inboard (MIE) models, as well as various OMC and Crusader engines. It is designed to meet OEM specifications for reliable temperature monitoring.

This unit directly replaces Mercury part numbers 97258A1, 97258, 34625, FI6900152, and FI6900198; Sierra 18-5898; and Rldym 171960.

• Installation: Direct replacement with no modifications required.
• Connection: Features a single electrical terminal (10-32 stud).
• Operating Range: Accurately reads temperatures up to 240°F (115°C).

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. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Technical Specifications

Package Contents

• 1 x Temperature Sender (97258A1/171960)

Installation Guide

1. Ensure the engine is completely cool and disconnect the negative battery terminal for safety.
2. Locate the existing water temperature sender on the engine block, cylinder head, or thermostat housing.
3. Place a drain pan under the sender to catch any coolant that may spill during removal.
4. Disconnect the electrical wire attached to the sender's terminal.
5. Using an appropriate wrench, carefully unscrew and remove the old sender from the engine.
6. Apply a suitable thread sealant to the threads of the new sender to prevent leaks.
7. Install the new sender by screwing it in by hand, then tighten securely with a wrench. Do not overtighten.
8. Reconnect the electrical wire to the new sender's terminal.
9. Reconnect the negative battery terminal.
10. Refill or top off the engine coolant to the proper level.
11. Start the engine, check for any leaks around the new sender, and verify the temperature gauge is functioning correctly.

Troubleshooting & FAQ

How do I confirm this sender fits my engine?
First, check the 'Part Number Cross-Reference' table to see if your old part number is listed. Next, review the 'Compatible Engine Models' table. Finally, visually compare the product images and verify that the 1/2" - 14 NPT thread size and single-stud electrical connection match your current part.

What are common signs my water temperature sender is failing?
A faulty sender can cause your temperature gauge to read inaccurately (e.g., always cold or maxed out), fluctuate erratically, or not work at all. It may also trigger false overheating alarms on the console.

Is any special sealant required for installation?
Yes, applying a small amount of pipe thread sealant or Teflon tape to the sender's threads is recommended to ensure a leak-proof seal.

OEM vs. Aftermarket?
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.

How fast do you ship and how much does it cost?
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.

What is your warranty and return policy?
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.