Water Temperature Sensor – Fits Mercury/Mercruiser, Volvo Penta, OMC (Replaces 3853787, 806490T)
Water Temperature Sensor – Fits Mercury/Mercruiser, Volvo Penta, OMC (Replaces 3853787, 806490T) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Water Temperature Sensor – Fits Mercury/Mercruiser, Volvo Penta, OM...
Product Details
This Water Temperature Sensor – Fits Mercury/Mercruiser, Volvo Penta, OMC (Replaces 3853787, 806490T) is a direct replacement sender for your boat's temperature gauge. It is designed for a broad range of marine engines, including most Mercury/Mercruiser V6 & V8 models from 1988 and up, as well as specific Volvo Penta and OMC stern drives that utilize a 3/8" NPT threaded sender.
It provides a reliable cross-reference for OEM parts such as Mercury 806490T, Volvo Penta 3853787, and OMC 980613, along with aftermarket numbers including Sierra 18-5897 and Mallory 9-42400.
- Installs directly with a standard 3/8"-18 NPT threaded fitting.
- Engineered for use with dashboard water temperature gauges, not for warning alarms.
- Durable brass and metal construction ensures longevity in marine environments.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury/Mercruiser | 806490T |
| Mercury/Mercruiser | 97257A1 |
| Volvo Penta | 3853787 |
| OMC | 980613 |
| Sierra | 18-5897 |
| Mallory | 9-42400 |
| Stewart Warner | 352BC-D |
| Medallion | A-2618-3 |
| VeeThree Seastar | 52320S018 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury/Mercruiser, this sender fits most V6 and V8 engines from 1988 onwards using a 3/8" NPT fitting. Compatibility for 4-cylinder models should be verified against your OEM part number.
For Volvo Penta and OMC, this sender is applicable to engines that specify the original equipment part numbers listed in the table.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercruiser | MCM/MIE engines | V6 & V8 | 4-Stroke | 1988 and up | 806490T, 97257A1, 22-811091 | For all engines using 3/8" water temp sender |
| Mercruiser | 2.5L | 4 cyl | 4-Stroke | 806490T | Verify application | |
| Mercruiser | 3.0L | 4 cyl | 4-Stroke | 806490T | Verify application | |
| Volvo Penta | Various | Various | 4-Stroke | 3853787 | For engines requiring OEM part #3853787 | |
| OMC | Stern Drive | Various | 4-Stroke | 980613, 3853787 | For engines requiring OEM parts #3853787, 980613 |
Technical Specs
- Product Type
- Water Temperature Sensor
- Installation
- Direct replacement, 3/8" NPT threaded
- Thread Size
- 3/8" or 9.5mm -18 NPT
- Terminal Type
- 10-32 stud
- Temperature Range
- 240° DS
- Housing Material
- Brass/Metal
- Housing Color
- Gold tone
- Application
- Water temperature gauge sender (not for alarm)
- Compatibility
- V6 & V8 engines using 3/8" NPT fitting
- Usage
- For marine inboard engines and stern drives
What’s in the Box
- 1 x Water Temperature Sending Unit (3853787/806490T)
Installation Notes
- Ensure the engine is completely cool and disconnect the negative battery terminal.
- Drain the engine coolant to a level below the sensor's location to prevent spills.
- Carefully disconnect the wire from the existing temperature sensor.
- Using the correct size wrench, unscrew and remove the old sensor from the engine block or manifold.
- Clean the threads in the port to ensure a clean surface for the new sensor.
- Apply a suitable marine-grade thread sealant to the threads of the new sensor. Avoid getting sealant on the sensor tip.
- Screw the new sensor in by hand, then tighten securely with a wrench. Do not overtighten, as this can damage the sensor or engine block.
- Reconnect the wire to the 10-32 stud terminal on the new sensor.
- Refill the cooling system with the appropriate coolant.
- Reconnect the battery, start the engine, and check for any leaks around the sensor. Monitor the temperature gauge to ensure it is functioning correctly.
Troubleshooting & FAQ
How do I confirm this sensor fits my engine?
The best way is to verify your existing sensor has a 3/8" NPT thread size and to cross-reference its part number with those listed in our Part Number Matrix. It is primarily for Mercruiser, Volvo Penta, and OMC V6/V8 engines.
Is this for the warning alarm or the temperature gauge?
This is a sender for the water temperature gauge only. It is not designed to trigger a warning light or audible alarm.
What are common signs of a failing temperature sender?
Symptoms of a faulty sender include a temperature gauge that reads incorrectly (e.g., too high or too low), is pegged at one extreme, or does not move at all once the engine is warm.
Can I use this sensor for an oil temperature gauge?
While physically similar to some oil temperature senders, this unit is specifically calibrated for water temperature ranges. For accurate oil temperature readings, a dedicated oil temperature sender should be used.
Do I need to apply sealant to the threads?
Yes, applying a marine-grade thread sealant or Teflon tape to the sensor's threads before installation is highly recommended to create a leak-proof seal.
What is the difference between a sender and a sensor/switch?
A "sender" or "sending unit" (like this part) provides a variable signal to a gauge to show a range of temperatures. A "sensor" or "switch" typically operates an on/off warning light or alarm at a single, preset temperature.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
Payment & Security
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