How to Change the Coolant in a 2018 Sherco 300SEF-R
Shop parts for a 2018 Sherco 300SEF-R Dirt Bike.The 2018 Sherco 300SEF-R uses a closed-loop liquid cooling system designed to keep the high-performance, four-stroke engine at optimal temperature under demanding conditions. Regular coolant changes are vital to protect your engine and extend performance life. Here is the proprietary MotoSport guide to changing your coolant safely and efficiently–along with essential owner tips specific to the Sherco 300SEF-R.
Why Coolant Changes Matter on the 300SEF-R
This model's compact, high-compression four-stroke motor works hard and runs hot. Sherco specifies not to use water or non-approved fluids, as they can cause engine damage and lead to premature corrosion or overheating. Always use a high-quality, manufacturer-recommended coolant meeting at least Minerva Perma Universal D 4 -25°C specification†.
What You'll Need
- Correct coolant (at least 1.1 liters, Minerva Perma Universal D 4 or equivalent)
- Socket set or spanners (for drain bolt and bleed screw)
- Drip pan or container for old coolant
- Funnel
- Shop rags
- Gloves and eye protection
- Optional: Replacement gasket for bleed screw, depending on condition
Coolant Change Procedure
- Ensure the bike is cool and standing upright on level ground for safety and accurate draining.
- Locate the radiator cap (typically on the left side, top of the radiator) and remove it.
- Place a catch pan beneath the bike, directly under the coolant drain screw (usually on the lower side of the water pump)†.
- Remove the coolant drain screw and allow the old coolant to flow completely out. Dispose of the coolant properly at your local recycling or waste center.
- Remove the radiator bleed screw (found on the left side of the radiator) to help coolant drain more thoroughly and allow fresh fill to purge air from the system†.
- Inspect and replace the bleed screw gasket if it shows any damage or wear.
- Reinstall the drain screw (torque to 6Nm) and bleed screw gasket if required, then reinstall the bleed screw (torque to 8Nm)†.
- Slowly pour fresh coolant into the radiator until it reaches the fill neck. Watch for bubbles at the bleed screw; keep filling until only coolant (no air) emerges, then tighten the bleed screw.
- Continue topping up until the radiator is completely full (typically about 1.1 liters in total).
- Replace the radiator cap securely.
- Start the engine and let it idle until it reaches normal operating temperature, then shut off and let cool. Re-check coolant level in the radiator and the expansion tank, replenishing if needed.
Model-Specific Tips for the 2018 Sherco 300SEF-R
- Be alert for leaks at the water pump area. If coolant appears at the weep hole, this may indicate a water pump seal issue—which is not uncommon on these engines after prolonged use. This requires additional service involving clutch cover removal.
- Always inspect the radiator cap seal. Air leaks here can cause recurring overheating or air bubbles in the cooling system.
- 2018 300SEF-R models are known for compact radiator sizing. Make sure your radiator fins are clean and unobstructed to prevent overheating—especially after mud rides.
- Only fill with the recommended coolant type, as incorrect fluids can cause aluminum corrosion or head gasket deterioration specific to Sherco's engine design.
- Monitor coolant level regularly; this model has a visible expansion tank for quick checks. If you experience unexplained coolant loss, inspect hose clamps and radiator seams.
Final Checks
- After each coolant change, check again after your first ride, as residual air pockets may burp out into the expansion tank—top off if needed.
- Regularly change coolant as specified in your owner's manual or at least every two years for maximum engine longevity.
Following this procedure ensures your Sherco 300SEF-R is ready for trail, race, or adventure with reliable cooling. If you spot seal leaks, visible corrosion, or /persistent temperature spikes/, schedule professional inspection as soon as possible.
† Source: Sherco 300SEF-R Workshop Manual.
Related Shopping Categories
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Shop Radiator Hoses for a 2018 Sherco 300SEF-R Dirt Bike.
Disclaimer: This guide is provided for general informational purposes only and is not intended to replace your motorcycle's official owner's manual. Always refer to your manufacturer's documentation for model-specific instructions, torque specifications, safety procedures, and maintenance requirements. If you are unsure or inexperienced, consider seeking assistance from a qualified mechanic or technician.