How to bleed and replace brake fluid on a 2018 Textron Alterra 300

Shop parts for a 2018 Textron Alterra 300 ATV.

This proprietary MotoSport guide walks you through safely flushing and replacing the brake fluid on a 2018 Textron Alterra 300 ATV. Follow every step carefully. If you’re unsure at any point, stop and contact a qualified technician. This procedure assumes the bike is stock and the brake system has standard hydraulic calipers and a master cylinder typical of the Alterra 300 MMY.

Tools & supplies

  • Manufacturer-specified brake fluid (check owner’s manual for DOT rating; DOT 3 or DOT 4 are commonly used)
  • Clear plastic tubing that fits snugly over the bleeder nipples
  • Small catch bottle for old fluid
  • Wrench set (open-end for bleeder nuts)
  • Turkey baster or fluid syringe (for removing reservoir fluid)
  • Clean rags and nitrile gloves
  • Brake cleaner
  • Jack or stand to keep machine level and stable
  • Assistant (recommended) or one-person vacuum bleeder

Model-specific notes for the Alterra 300

  • Master cylinder locations: front master cylinder is mounted on the handlebar; the rear master cylinder is typically located at the rear brake pedal or near the rear caliper depending on year/configuration. Inspect your machine to confirm exact placement before starting.
  • Reservoir caps may use small rubber diaphragms & plastic screens — keep these clean and reinstall exactly as removed.
  • Bleeder nipples are exposed on the calipers but can collect mud. Clean around nipples before opening to avoid contamination.
  • The Alterra 300 does not use factory ABS components; bleeding is straightforward hydraulic work. If aftermarket components or modifications exist, consult that equipment’s documentation.
  • Brake lines on this model are accessible but routed for protection. Avoid sharp bending or kinking when working the hoses.

Safety first

  • Work on a flat, stable surface with ignition OFF and the key removed.
  • Wear gloves and eye protection. Brake fluid is corrosive & damages painted surfaces. Immediately wipe spills and rinse with water.
  • Never reuse contaminated fluid. Dispose of old fluid following local hazardous-waste regulations.

Preparation

  1. Park the ATV upright on a stand so wheels can rotate and the machine is level.
  2. Remove mud, debris, and clean the master cylinder reservoir cap area and caliper bleeder screws with brake cleaner.
  3. Open the reservoir cap and use a turkey baster or syringe to remove as much old fluid as possible from the reservoir. Leave the cap loosely seated to minimize air entry.
  4. Top up the reservoir with fresh brake fluid of the correct DOT rating. Do not let the reservoir run dry during the procedure.

Bleeding method A Two-person pump-and-hold (recommended if you have an assistant)

  1. Attach clear tubing to the caliper bleeder nipple and place the other end into a catch bottle partially filled with clean brake fluid to avoid air re-entry.
  2. Have your assistant slowly depress the brake lever or pedal to build firm pressure and hold it.
  3. While lever is held, open the bleeder nipple one-quarter to one-half turn to let fluid and air escape. Watch for bubbles in the tubing. Close the nipple before the assistant releases the lever.
  4. Repeat pump/hold/open/close cycles until no air bubbles appear and fluid running out is clear and free of contamination.
  5. Keep the reservoir topped between cycles. Work from the least accessible/nearest-to-reservoir caliper outward if the system circuits are separate — typical practice is to bleed farthest wheel first. For many ATVs bleed: rear (farthest), then front right, then front left; confirm routing on your Alterra before beginning.
  6. Tighten bleeder to spec (hand tight plus a small quarter-turn; do not overtighten), wipe any spilled fluid, and reinstall reservoir cap.

Bleeding method B One-person vacuum or pressure bleeder

  1. Attach vacuum bleeder to the bleeder nipple or connect a pressure bleeder to the master cylinder reservoir according to the tool instructions.
  2. Operate the tool to draw fluid through the caliper until clear fluid flows and no bubbles appear.
  3. Maintain reservoir level and follow tool safety instructions. Close bleeder and remove tubing once complete.

Full system flush (recommended interval or when fluid is dark)

  1. Perform the above bleeding sequence on each caliper or brake circuit until fluid exiting each bleeder is bright and of the correct color/consistency.
  2. Replace reservoir diaphragm/screen if deteriorated. Inspect lines, hoses, and fittings for cracks, swelling, or leaks — replace any suspect components.
  3. After bleeding all circuits, verify pedal/lever feel is firm with no creep. If feel is spongy, repeat bleeding steps.

Post-bleed checks

  • Torque bleeder screw to specification if available; otherwise secure snugly without over-torquing.
  • Inspect for leaks at calipers, hose connections, and master cylinder. Start the engine only if no leaks are present and controls feel normal.
  • Bed-in new fluid/brake pads with gentle braking runs before heavy use.

Troubleshooting

  • Persistent spongy lever: likely remaining air or leak. Recheck fittings and repeat bleeding.
  • Dark fluid quickly after flush: indicates contamination or old fluid deep in calipers & lines. Consider repeating flush and inspecting internal components.
  • Leaking bleeder: replace the bleeder nipple or caliper seal if needed.

Maintenance tips specific to the Alterra 300

  • Check fluid color every 12 months or 1,000 miles, whichever comes first. Replace if dark or contaminated.
  • Keep the reservoir cap and vent screen clean to avoid dirt entering during off-road use.
  • If you operate in mud or salt conditions frequently, inspect lines and fittings more often for corrosion or abrasion damage.
  • Store spare bleeder screws, banjo bolt crush washers, and the correct DOT fluid in your toolbox for field service.

Following this MotoSport proprietary procedure will restore braking performance safely and reliably on your 2018 Textron Alterra 300. If you encounter unexpected mechanical issues, consult a certified technician or MotoSport service resources.

Related Shopping Categories

Shop Brake Fluid for a 2018 Textron Alterra 300 ATV.

Shop Brake Bleeders for a 2018 Textron Alterra 300 ATV.

Shop Brake Pads for a 2018 Textron Alterra 300 ATV.

Shop Brake Lines for a 2018 Textron Alterra 300 ATV.

Shop Brake Tools for a 2018 Textron Alterra 300 ATV.

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.