Temperature Sensor Sender – Fits MerCruiser 3.0 4.3 5.0 (Replaces 805218T, 805218, 18-7600)

Product Details

This Temperature Sensor Sender is designed for MerCruiser engines including 3.0, 4.3, and 5.0 models. It accurately monitors engine temperature and transmits data to your gauge, ensuring optimal performance and preventing overheating damage.

This aftermarket unit replaces MerCruiser OEM part numbers 805218T and 805218, as well as Sierra 18-7600.

• Direct-fit replacement for MerCruiser temperature senders
• Compatible with 3.0L, 4.3L, and 5.0L MerCruiser inboard and sterndrive engines
• Matches OEM connector and thread specifications

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Engine & Model Compatibility

Confirm your engine model/year in the table below.

Technical Specs

Part Type

Temperature Sensor / Sender

Application

MerCruiser inboard and sterndrive engines

Replaces OEM

805218T, 805218

Aftermarket Equivalent

18-7600

What's in the Box

• 1 × Temperature Sensor Sender

Installation Notes

1. Disconnect the battery before beginning any work on the engine.
2. Allow the engine to cool completely to avoid burns from hot coolant or engine surfaces.
3. Locate the existing temperature sender on your engine block or manifold.
4. Disconnect the electrical connector from the old sender.
5. Use an appropriately sized wrench or socket to carefully unthread the old sensor.
6. Apply a small amount of thread sealant (if specified by your engine manufacturer) to the new sender threads.
7. Thread the new temperature sender into the mounting hole and tighten to the manufacturer's torque specification.
8. Reconnect the electrical connector and ensure it locks securely.
9. Reconnect the battery and start the engine to verify proper gauge operation.

Troubleshooting & FAQ

How do I know if my temperature sender is failing?

Common symptoms include erratic gauge readings, a gauge that stays at zero or maximum, or an overheat alarm that triggers without the engine actually being hot. If your engine runs normally but the temperature display is unreliable, the sender is often the culprit.

Will this sensor fit my MerCruiser 4.3L V6?

Yes, this sender is compatible with MerCruiser 3.0, 4.3, and 5.0 engines. Verify that your existing sender bears part number 805218T or 805218 to confirm fitment.

What thread size does this sender use?

This sender matches the OEM thread specification for MerCruiser 805218T. It installs directly into the factory mounting location without modification.

Do I need thread sealant for installation?

Check your engine's service manual. Some applications require a small amount of thread sealant or tape on the threads, while others use a tapered pipe thread that seals without additional compounds.

Can I test the sender before installing it?

Yes, you can use a multimeter to measure resistance at various temperatures. Compare your readings to the sender's resistance curve in the service manual to verify proper operation.

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 against 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.