Honda BF15D / BF20D Thermostat Replacement Guide (15HP / 20HP Outboards)
By customer request, we’re starting a series of simple workshop guides to help you service, repair, and maintain your outboard engine.
We’re kicking things off with a common service job — replacing the thermostat on Honda BF15D and BF20D outboards (15HP and 20HP models).
This is a straightforward job that plays an important role in keeping your engine running at the correct temperature.
🎥 Video Guide
Embed your video here 👇
https://youtu.be/dExEn3qg7cg
🔧 Why the Thermostat Matters
The thermostat controls engine temperature by regulating coolant flow.
A faulty thermostat can cause:
- Engine running too cold
- Poor fuel efficiency
- Increased engine wear
- Overheating (in some cases)
Regular inspection and replacement helps maintain performance and reliability.
⚙️ What This Video Covers
- Accessing the thermostat housing
- Removing the old thermostat
- Inspecting for faults or wear
- Installing the new thermostat
- Reassembly
🧰 Tools Required
- Socket set
- Screwdrivers
- Replacement thermostat and gasket
🛠️ Compatible Models
- Honda BF15D
- Honda BF20D
(15HP & 20HP models)
🛒 Parts Required
You can find the correct thermostat for these models here:
👉 [PASTE PRODUCT LINK HERE]
💡 Workshop Tip
Always check the condition of the gasket or seal when replacing the thermostat.
If damaged or worn, replace it to avoid leaks.
🔄 Part of Our Workshop Series
This is the first video in our new SSI Marine workshop series.
We’ll be adding more guides covering:
- Service kits
- Impeller changes
- Carburettor work
- General maintenance
If there’s a job you’d like us to cover, feel free to get in touch.
⚠️ Buyer Responsibility
Please confirm compatibility with your engine model and serial number before purchasing parts.
If you’re unsure, contact us — our technical team will be happy to help.
🔵 Why Buy from SSI Marine
- Workshop-tested aftermarket & OEM-spec parts
- Fast UK dispatch (same-day before 1 PM Mon–Fri)
- Tracked 24-hour UK delivery
- UK stock – collection available from Leigh (Manchester)
- Technical support available
