How to Bleed and Replace Brake Fluid on a 2020 Polaris Scrambler 850
Shop parts for a 2020 Polaris Scrambler 850 ATV.
This MotoSport guide covers step-by-step bleeding and replacement of brake fluid on a 2020 Polaris Scrambler 850 (MMY Polaris;SCRAM850;2020). It includes model-specific notes you should know before beginning, recommended tools, a safe procedural sequence, and post-service checks.
Model-specific notes for the 2020 Polaris Scrambler 850
- The Scrambler 850 uses separate front and rear hydraulic brake circuits with individual reservoirs. Confirm reservoir locations before starting and work on one circuit at a time.
- Polaris recommends using high-quality DOT brake fluid. DOT 4 is commonly used for modern ATVs because of higher boiling resistance; check your owner’s manual or reservoir cap for the exact specification for your unit.
- Some Scrambler 850 models have remote-mounted reservoirs and short flexible hoses on calipers. Inspect hoses, banjos, and fittings for wear or seepage before bleeding. Replace any components that show damage.
- The rear brake master cylinder is hydraulically separate from the front. Bleeding one circuit will not affect the other.
- ABS is not common on this model; if your unit is fitted with any electronic brake assist, consult a dealer prior to service.
Tools & materials
- DOT 4 brake fluid (or type specified in your manual)
- Clear vinyl hose to fit bleed nipple
- Catch bottle and some brake fluid-safe rags
- Wrench for bleed nipples (usually 8-11 mm; verify on your bike)
- Turkey baster or fluid transfer pump to remove old fluid from reservoirs
- Brake bleeder kit or vacuum pump OR a helper for manual pedal/lever bleeding
- Latex or nitrile gloves, eye protection
- Torque wrench for reassembly where needed
Safety & prep
- Work on a cool machine parked on level ground with the parking brake engaged and wheels chocked.
- Wear eye protection and gloves. Brake fluid damages paint and plastics – cover painted surfaces and clean spills immediately.
- Open reservoirs and inspect fluid color. Dark brown/black fluid is degraded and needs replacement.
- Top reservoirs with just enough fresh fluid to prevent air entry during bleeding, but do not overfill.
Bleeding strategy & circuit order
Bleed each circuit separately. The best general sequence is to start with the circuit farthest from its master cylinder and work toward the master. For the Scrambler 850 this typically means:
- Rear brake circuit (rear caliper bleeding first, if more than one rear caliper bleed the farthest rear wheel first).
- Front brake circuit – bleed the front calipers farthest from the front master cylinder first, then the nearest. On most Scrambler layouts that is right-front then left-front, but confirm by tracing the hose path from the front master.
Step-by-step bleed and fluid replacement
- Remove reservoir covers and clean around caps to prevent contamination. Remove old fluid to below the halfway mark using a turkey baster or syringe.
- Refill with fresh DOT 4 fluid to just below the fill line.
- Attach clear hose to the bleed nipple on the caliper you’re starting with and route the other end into a catch bottle partially filled with fresh fluid to prevent air being sucked back in.
- Loosen the bleed nipple about a quarter turn. If using a vacuum pump, apply vacuum and open the nipple while you squeeze the brake lever/pedal slowly several times until new fluid runs clear and air bubbles are gone. Close the nipple before releasing vacuum/lever.
- If bleeding with a helper: have the helper slowly squeeze the lever/pedal until firm, hold it, open the bleed nipple to allow fluid/air out until flow slows, then close the nipple; the helper releases the lever. Repeat until fluid runs clear with no bubbles. Always close the nipple before the helper releases pressure.
- Keep the reservoir level topped up throughout the procedure to prevent introducing air into the master cylinder.
- Move to the next caliper in the sequence and repeat until all calipers in that circuit show clear, bubble-free fluid.
- Once complete, tighten bleed nipple to proper snugness. Clean any spilled fluid and reinstall reservoir cap(s).
Vacuum or pressure bleeding tips
- Vacuum bleeders reduce mess and make single-person bleeding practical. Use a bleeder adapter that seals to the reservoir if pressure bleeding.
- Do not reuse old fluid you draw into a catch bottle for topping off the reservoir. Dispose of contaminated fluid properly.
Inspection & reassembly
- After bleeding, check for leaks at bleed nipples, banjo bolts, hose clamps and master cylinder fittings. Tighten as needed to spec if available.
- Wipe down all components to remove traces of fluid. Replace any soaked brake pads or hardware that look contaminated.
- Pump the brake lever/pedal several times until firm. If it feels spongy, there is still air in the system — repeat bleeding.
Final checks & test ride
- With the machine off, confirm lever/pedal firmness and return. Start the engine and test brakes at low speed in a safe area before normal riding.
- Recheck reservoir levels after a short test ride and top as necessary. Reinspect fittings for leaks after riding.
- Record the service date and fluid type used for future maintenance.
Maintenance interval & disposal
- Brake fluid absorbs moisture over time. For off-road and performance use, consider replacing brake fluid every 1-2 years. For typical trail use, follow the owner’s manual schedule.
- Dispose of used brake fluid at an approved hazardous waste facility; do not pour it down drains or onto the ground.
Common problems and troubleshooting
- Persistent spongy lever after bleeding — check for internal master cylinder leaks, contaminated pads, or a stuck caliper piston.
- Fluid level dropping quickly — search for leaks at banjo bolts, calipers, hoses, and master cylinder seals.
- Brake fade under heavy use — consider branded high-temperature DOT 4 fluid and inspect pads & rotors for wear.
Follow this MotoSport-specific procedure and the 2020 Polaris Scrambler 850 owner’s manual recommendations to ensure a safe, effective brake fluid change and bleed. If you encounter internal master cylinder or ABS-related issues, consult a qualified Polaris technician.
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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.