How to Change the Coolant in a 1988 Yamaha XT350
Shop parts for a 1988 Yamaha XT350 Dirt Bike.
Keeping the cooling system in top shape is essential for maintaining your 1988 Yamaha XT350's performance – especially for extended adventures off-road. Unlike many air-cooled dirt bikes of its era, the XT350 utilizes a liquid-cooled dual overhead cam single, so proper coolant service ensures a long and healthy engine life.
Essential Tools & Supplies
- Metric socket set (10mm for drain bolts)
- Drain pan
- Distilled water
- Fresh motorcycle coolant (pre-mixed or concentrated, see owner's manual for type)
- Funnel
- Shop rags
- Protective gloves & eyewear
Changing the Coolant Step-by-Step
- Let the XT350 fully cool before beginning. Hot coolant can scald and pressurize the system—open only when cool.
- Remove the seat and side panels for better access to the radiator and coolant reservoir if applicable.
- Locate the radiator cap and reservoir. The XT350's radiator cap sits on the top of the radiator. Crack this open to let air in (leave it loosely fitted until draining is complete).
- Find the coolant drain bolt. Yamaha typically places a 10mm bolt on the steel pipe leading from the cylinder block to the water pump. The bolt features a sealing washer—set both aside for inspection or replacement.
- Position your drain pan underneath, then remove the drain bolt and allow old coolant to flow into the pan. Tilt the bike gently if needed.
- Inspect and clean the drain bolt. Replace the sealing washer with a new one if you see damage or deformation.
- Flush with distilled water (optional but recommended). Replace the drain bolt temporarily, fill the system with distilled water, run the engine for a few minutes, then drain again. Repeat until the water runs clear to remove old coolant and deposits.
- Reinstall and torque down the drain bolt. Avoid over-tightening to prevent damage to the threads or washer.
- Fill the radiator with fresh, correct-mix coolant. Fill slowly using a funnel until coolant reaches the bottom of the filler neck. Some air will naturally be trapped in the system, so top it off as needed.
- 'Burp' the cooling system. Start the XT350 with the radiator cap off. Let it idle, and gently rock the bike or squeeze the coolant hoses to help any air bubbles escape. When bubbles stop appearing, top off coolant to the base of the filler neck.
- Bleed the water pump if specified. Some XT350s have a small purge or bleeder bolt on the water pump housing. Carefully loosen it until only coolant (not air) escapes, then tighten securely.
- Tighten the radiator cap and reservoir cap. Run the bike until the fan (if equipped) operates or the engine warms fully. Let cool, then recheck and top off the coolant. Fill the overflow reservoir to the appropriate line if your model has one.
- Check for leaks, reinstall panels, and properly dispose of used coolant at a recycling center.
XT350-Specific Tips & Notes
- The XT350's steel coolant pipe and aging gaskets may be susceptible to leaks or corrosion, particularly if incorrect or old coolant was used previously. Carefully check the drain bolt washer and investigate any signs of seepage.
- Always use distilled water–NOT tap water–when flushing or mixing coolant to prevent mineral deposits inside the radiator and water jackets.
- Check the condition of radiator hoses for cracks or brittleness. Replace as needed to avoid roadside failures.
- Take care not to overtighten radiator and water pump bolts; these vintage bikes often have delicate threads.
- The XT350 shares coolant maintenance needs with other Yamaha dual-sports of the late 80s, but some parts (such as drain bolt gaskets) are specific, so check compatibility before buying replacements.
Why Regular Coolant Changes Matter
Over time, coolant loses its anti-corrosive and heat-transferring properties. Old coolant can lead to overheating, gasket failure, and internal corrosion. By following these steps, you'll keep your 1988 XT350 running safely and reliably for years to come.
Related Shopping Categories
Shop Radiators for a 1988 Yamaha XT350 Dirt Bike.
Shop Coolant for a 1988 Yamaha XT350 Dirt Bike.
Shop Temperature Sensors for a 1988 Yamaha XT350 Dirt Bike.
Shop Tools for a 1988 Yamaha XT350 Dirt Bike.
Shop Radiator Hoses for a 1988 Yamaha XT350 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.