How to Bleed and Replace Brake Fluid on a 2008 Polaris Sportsman 800 EFI 4X4
Shop parts for a 2008 Polaris Sportsman 800 EFI 4X4 ATV.This step-by-step MotoSport guide covers everything you need to safely replace and bleed the brake fluid on a 2008 Polaris Sportsman 800 EFI 4x4. Follow these instructions carefully, use proper PPE, and only use recommended fluids and parts to maintain braking performance and safety.
Tools & supplies
- DOT 4 brake fluid (Polaris recommends DOT 4; always use fresh, sealed fluid)
- Clear plastic tubing that fits snugly over bleeder screws
- Catch bottle or jar for old fluid, partially filled with fresh fluid to prevent air ingestion
- Hand vacuum pump or squeeze bulb bleeder (optional but speeds procedure)
- Wrenches to fit bleeder screws and flare nuts (usually 8mm-11mm)
- Clean rags, brake cleaner, and a funnel or bleed kit cap adapter
- Jack stands or ATV lift to secure the machine upright
- Latex or nitrile gloves and eye protection
Model notes for the 2008 Polaris Sportsman 800 EFI 4X4
- The Sportsman 800 uses a sealed master cylinder reservoir positioned near the handlebars; reservoir may be under a protective cover on some trim packages.
- This model is built with hydraulic disc brakes front & rear; each caliper has a single bleeder screw. The rear and front lines converge at the master cylinder; bleed sequence aims to remove air from the entire system.
- The Sportman 800 EFI does not have an advanced ABS system that complicates bleeding, but the hydraulic travel may be longer than smaller ATVs so allow extra fluid volume during replacement.
- Use DOT 4 only. Do not mix DOT 5 silicone fluid with DOT 4; mixing will damage seals.
- Inspect caliper hoses, banjo fittings, and master cylinder for corrosion or leaks as you work. Replace any cracked hoses or rounded bleeder screws before finishing the job.
Preparation
- Park the ATV on level ground, engine off, parking brake disengaged, and key removed.
- Stabilize on a lift or jack stands so wheels can be rotated freely and you can access calipers.
- Clean around the master cylinder cap and reservoir area. Remove cap and diaphragm carefully to prevent contamination.
- Note fluid color – dark, dirty fluid indicates the system is due for a full replacement and possibly caliper rebuilding if contamination is severe.
Procedure: Replace and bleed the fluid
These instructions assume a complete system flush and bleed. Work quickly to prevent dirt or moisture entering the reservoir.
- Drain old fluid from the reservoir: use a syringe or siphon to remove as much fluid as possible from the master cylinder reservoir without introducing air.
- Refill reservoir with fresh DOT 4 fluid to the full mark.
- Start at the caliper farthest from the master cylinder. On the Sportsman 800 that is typically the rear caliper, then the front calipers. If uncertain, follow the longest hydraulic run to the shortest.
- Fit clear tubing over the bleeder screw and route into the catch bottle partially filled with fresh fluid to prevent sucking air back in.
- Have an assistant slowly depress the brake lever/pedal several times and hold it down. Open the bleeder screw about a quarter turn until fluid flows with no bubbles, then close the screw. Repeat until fluid runs clear and bubble-free. If using a vacuum or one-way bleeder, follow its instructions to draw fluid while keeping the reservoir topped up.
- Keep the reservoir topped between cycles. Never allow the reservoir to go below the minimum level; air entering the system forces you to start over.
- Repeat the bleed procedure on the remaining calipers, moving from farthest to nearest to the master cylinder.
- After all calipers are bled and fluid is clear, tighten bleeder screws to proper snugness. Wipe any spilled fluid immediately; brake fluid will damage paint and plastics.
- Top the reservoir to the correct level, reinstall diaphragm and cap, and secure any protective cover.
- Pump the brake lever/pedal to confirm a firm, consistent feel. If the lever feels spongy, repeat bleeding until firm.
- Lower the ATV, test brakes at low speed in a safe area to verify performance before normal operation.
Tips & troubleshooting
- If you see persistent air or a soft lever, inspect the master cylinder seals, caliper pistons, and lines for leaks or damage.
- Stubborn air pockets can be coaxed out by elevating wheels or rotating them while bleeding to change fluid paths in calipers.
- Replace bleeder screws or crush washers if they leak or are rounded. Always use new copper crush washers on banjo fittings.
- Dispose of old brake fluid per local hazardous waste regulations; do not pour it on the ground.
- If the brake system has been contaminated with water or oil, consider a full caliper overhaul or replacement to avoid corrosion and seal failure.
Post-service inspection
- After the first short ride, recheck fluid level and bleeder screws for leaks.
- Inspect brake pad wear and rotor condition while performing the service — replace pads or resurface/replace rotors if glazing or scoring is present.
Regular brake fluid replacement keeps the Sportsman 800 stopping reliably and protects hydraulic components from moisture-related corrosion. Follow OEM service intervals and inspect the system annually or more often if used in wet, muddy, or utility conditions.
Related Shopping Categories
Shop Brake Fluid for a 2008 Polaris Sportsman 800 EFI 4X4 ATV.
Shop Brake Bleeders for a 2008 Polaris Sportsman 800 EFI 4X4 ATV.
Shop Brake Pads for a 2008 Polaris Sportsman 800 EFI 4X4 ATV.
Shop Brake Lines for a 2008 Polaris Sportsman 800 EFI 4X4 ATV.
Shop Brake Tools for a 2008 Polaris Sportsman 800 EFI 4X4 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.