How to bleed &replace brake fluid on a 2018 Polaris Scrambler 850
Shop parts for a 2018 Polaris Scrambler 850 ATV.
This MotoSport proprietary guide walks you through safely flushing and replacing brake fluid on a 2018 Polaris Scrambler 850 (Scram 850). It covers tools, fluid selection, step-by-step bleeding methods, troubleshooting, and model-specific notes every MMY Scrambler owner should know.
What you need
- DOT 4 brake fluid (Polaris recommends DOT 4; do not mix with DOT 3/5 unless specified by manual)
- Clear hose that fits bleeder nipples
- Catch bottle and a small amount of old fluid disposal container
- Wrenches for bleeder nipples (typically 8mm or 10mm)
- Syringe or turkey baster (to remove old fluid from the master cylinder reservoir)
- Rubber gloves, shop rags, and brake parts cleaner
- Bleeder kit or vacuum pump (optional but speeds the job)
- Torque wrench for caliper mount bolts if you remove calipers
Model-specific notes – 2018 Polaris Scrambler 850
- The Scrambler 850 uses hydraulic disc brakes front & rear. Reservoirs are accessible but positions differ — front master cylinder on the right handlebar; rear master cylinder is foot-operated near the frame. Confirm reservoir positions before starting.
- Most Scram 850 models are not fitted with ABS. If your unit has an ABS option or aftermarket ABS components, consult the service manual before bleeding; ABS systems require specific procedures.
- DOT 4 is the correct fluid for this model under normal conditions. Always replace with fresh, sealed DOT 4 fluid to maintain boiling point and corrosion protection.
- Brake system components on the Scrambler are exposed to mud & water; after off-road use check calipers, lines, and fittings for contamination or damage before bleeding.
Preparation
- Park on level ground and secure the vehicle with the parking brake engaged and wheels chocked.
- Clean area around reservoir caps and bleeder nipples to prevent contamination.
- Remove enough old fluid from each reservoir with a syringe to leave space for new fluid. Do not let reservoirs run dry.
- Top reservoirs with fresh DOT 4 fluid and loosely reinstall caps (or use a one-way vent cap if you have one).
Bleeding order principle
Always bleed from the caliper furthest from the master cylinder first, then work toward the closest. On ATVs that means identify the master cylinder location, then bleed calipers in order of distance. If uncertain, bleed each caliper individually and repeat a full pass until all lever/pedal feel is firm.
Manual (two-person) bleeding method
- Attach clear hose to bleeder nipple and submerge the free end in a small clear catch bottle partially filled with fresh fluid to prevent air re-entry.
- Have an assistant slowly depress the brake lever or pedal to about 3/4 travel and hold it there.
- Open the bleeder nipple about 1/4 turn until fluid & air bubbles flow into the hose, then close the nipple while the lever/pedal is still held.
- Tell your assistant to release the lever slowly. Repeat the sequence until no air bubbles appear in the hose and the expelled fluid is clear and fresh.
- Top the reservoir after every few cycles to prevent it from running dry.
- Work through each caliper in the proper order, finishing with the caliper nearest the master cylinder.
- After final bleed, tighten bleeder nipples to spec (hand tight plus a small fraction with wrench), wipe clean, and verify lever/pedal feel is firm with no sponginess.
Vacuum pump or pressure bleeder method
- Attach vacuum pump to bleeder nipple or use a pressure bleeder on the reservoir per tool instructions.
- Operate the tool until clean fluid runs without bubbles. Keep the reservoir topped with fresh fluid during the process.
- Vacuum/pressure methods are faster and reduce the chance of introducing air compared with manual pumping.
After bleeding
- Confirm brake lever/pedal feel: firm and consistent with no sink or excessive travel.
- Clean any spilled brake fluid immediately — it damages paint and plastics. Inspect lines, fittings, and calipers for leakage.
- Properly dispose of old brake fluid according to local hazardous-waste rules.
- Test ride at low speed in a safe area to verify braking performance before returning to regular use.
Troubleshooting
- Spongy pedal after bleeding: repeat bleeding sequence; check for air entry points and inspect master cylinder seals and hoses for leaks or collapse.
- Persistent soft brake feel with no visible leaks: consider master cylinder or caliper rebuilds, or contamination of system requiring a full hose/caliper replacement.
- If an ABS unit is present and the system will not purge, follow the OEM ABS bleeding procedure or seek dealer service.
Routine maintenance tips for Scrambler 850 owners
- Replace brake fluid every 1-2 years depending on riding conditions; more often if you ride in wet/muddy environments.
- Inspect brake lines for abrasion from racks, racks or trail debris — replace if swollen, cracked, or damaged.
- Keep a small bottle of DOT 4 and a spare bleeder cap in your trail toolkit for emergency top-ups.
- Record fluid changes in your maintenance log and check caliper guide pins and pads for uneven wear during service.
Following this MotoSport guide will keep the braking system on your 2018 Polaris Scrambler 850 performing reliably & safely. When in doubt about ABS-equipped units or major component failure, contact a certified Polaris technician.
Related Shopping Categories
Shop Brake Fluid for a 2018 Polaris Scrambler 850 ATV.
Shop Brake Bleeders for a 2018 Polaris Scrambler 850 ATV.
Shop Brake Pads for a 2018 Polaris Scrambler 850 ATV.
Shop Brake Lines for a 2018 Polaris Scrambler 850 ATV.
Shop Brake Tools for a 2018 Polaris Scrambler 850 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.