Polaris Sportsman 850 Problems

The Polaris Sportsman 850, a powerhouse of an ATV, is renowned for its robust performance and ability to tackle tough terrain. However, like any complex machine, it's not immune to issues. Understanding potential problems, and more importantly, knowing how to address them, can save you time, money, and frustration, keeping you riding instead of wrenching. Let's dive into some common challenges faced by Sportsman 850 owners and how to navigate them.

So, What's Going Wrong? Common Sportsman 850 Issues

While the Sportsman 850 is a capable machine, several recurring problems have been reported by owners. These range from minor annoyances to more serious mechanical failures. Knowing what to look for is half the battle.

1. EPS (Electronic Power Steering) Troubles:

A significant number of Sportsman 850 owners have experienced issues with the EPS system. This can manifest as a complete loss of power steering, intermittent assistance, or a jerky feeling in the steering.

• Why it happens: The EPS system relies on a complex network of sensors, a motor, and a control module. Corrosion in connectors, a failing sensor, or a faulty motor can all contribute to EPS failure. Low battery voltage can also throw the system into a fault state.
• What to do:
  • Check the battery: Ensure your battery is fully charged and in good condition. A weak battery can cause all sorts of electrical gremlins.
  • Inspect connections: Carefully examine all electrical connectors related to the EPS system for corrosion or loose connections. Clean and re-grease them with dielectric grease.
  • Check the fault codes: If possible, use a diagnostic tool to read any stored fault codes. These codes can provide valuable clues as to the source of the problem.
  • Inspect the EPS unit: Visually inspect the EPS unit itself for any signs of damage or leakage.
  • Professional diagnosis: If the problem persists, it's best to take your Sportsman to a qualified mechanic for diagnosis and repair. EPS systems can be complex, and specialized tools may be required.

2. Overheating Issues:

Overheating can be a serious problem for any ATV, and the Sportsman 850 is no exception. A hot engine can lead to decreased performance, component damage, and even engine failure.

• Why it happens:
  • Clogged radiator: Mud, debris, and even insects can clog the radiator fins, restricting airflow and reducing cooling efficiency.
  • Low coolant level: Insufficient coolant in the system reduces its ability to absorb and dissipate heat.
  • Faulty thermostat: A malfunctioning thermostat can prevent coolant from circulating properly.
  • Water pump failure: A failing water pump can't circulate coolant effectively.
  • Air lock in the cooling system: Air trapped in the system can prevent proper coolant circulation.
• What to do:
  • Clean the radiator: Regularly clean the radiator fins with a soft brush and low-pressure water. Avoid using a pressure washer, as it can damage the fins.
  • Check coolant level: Ensure the coolant level is at the proper mark in the overflow reservoir.
  • Inspect the thermostat: If you suspect a faulty thermostat, you can test it by placing it in a pot of hot water and observing whether it opens.
  • Check the water pump: Look for signs of leakage or unusual noises from the water pump.
  • Burp the cooling system: To remove air locks, follow the procedure outlined in your owner's manual for bleeding the cooling system.
  • Check the fan: Make sure the radiator fan is functioning properly.
  • Use appropriate coolant: Use the type of coolant recommended by Polaris.

3. Stator Failure:

The stator is responsible for generating electricity to charge the battery and power the electrical system. A failing stator can lead to a dead battery, starting problems, and other electrical issues.

• Why it happens: Heat, vibration, and age can all contribute to stator failure. Overloading the electrical system with aftermarket accessories can also put a strain on the stator.
• What to do:
  • Check the battery voltage: Use a multimeter to check the battery voltage while the engine is running. It should be around 13.5-14.5 volts. If it's significantly lower, the stator may be failing.
  • Test the stator: A multimeter can be used to test the stator's output. Consult your service manual for the specific testing procedure.
  • Inspect the wiring: Check the wiring harness for any signs of damage or corrosion.
  • Replace the stator: If the stator is faulty, it will need to be replaced. This is a relatively involved repair, so consider having it done by a professional.

4. Fuel Pump Issues:

The fuel pump delivers fuel from the tank to the engine. A failing fuel pump can cause starting problems, poor performance, and stalling.

• Why it happens: Debris in the fuel tank, age, and overheating can all contribute to fuel pump failure.
• What to do:
  • Check the fuel filter: A clogged fuel filter can restrict fuel flow and put a strain on the fuel pump. Replace the fuel filter regularly.
  • Listen for the fuel pump: When you turn the key to the "on" position, you should hear the fuel pump prime for a few seconds. If you don't hear it, the fuel pump may be failing.
  • Check fuel pressure: Use a fuel pressure gauge to check the fuel pressure at the fuel rail. Consult your service manual for the correct pressure specification.
  • Inspect the fuel tank: Check the fuel tank for debris or contamination.
  • Replace the fuel pump: If the fuel pump is faulty, it will need to be replaced.

5. Clutch Problems:

The clutch transfers power from the engine to the transmission. Problems with the clutch can lead to slipping, jerky engagement, and difficulty shifting.

• Why it happens: Excessive wear, contamination, and improper adjustment can all contribute to clutch problems.
• What to do:
  • Inspect the clutch components: Visually inspect the clutch plates, springs, and other components for wear or damage.
  • Clean the clutch: Clean the clutch components with a solvent to remove any dirt or grease.
  • Adjust the clutch: Adjust the clutch according to the specifications in your service manual.
  • Replace worn components: Replace any worn or damaged clutch components.

6. Differential Problems:

The differential allows the wheels to turn at different speeds when cornering. Issues with the differential can manifest as clicking noises, difficulty steering, or even complete failure.

• Why it happens: Low fluid levels, contamination, and excessive wear can all contribute to differential problems.
• What to do:
  • Check the differential fluid level: Ensure the differential fluid is at the proper level.
  • Inspect the fluid: Check the fluid for contamination or metal shavings.
  • Change the fluid: Change the differential fluid according to the recommended maintenance schedule.
  • Inspect the differential components: Visually inspect the differential components for wear or damage.

Preventing Problems: A Stitch in Time

Regular maintenance is key to preventing many of the common problems associated with the Sportsman 850. Here are some essential maintenance tasks:

• Regularly check and change fluids: This includes engine oil, coolant, differential fluid, and brake fluid. Follow the recommended maintenance schedule in your owner's manual.
• Keep the radiator clean: Regularly clean the radiator fins to ensure proper airflow.
• Inspect and clean electrical connections: Check electrical connections for corrosion and clean them with dielectric grease.
• Keep the battery charged: A weak battery can cause all sorts of problems.
• Use high-quality fuel: Avoid using low-quality fuel, as it can contain contaminants that can damage the fuel system.
• Store your ATV properly: When storing your ATV for extended periods, use a fuel stabilizer and disconnect the battery.

Frequently Asked Questions

• Why is my Sportsman 850 overheating? Overheating can be caused by a clogged radiator, low coolant level, faulty thermostat, or water pump failure. Regularly cleaning the radiator and checking fluid levels can help prevent overheating.
• What causes EPS failure? EPS failure can be caused by corrosion in connectors, a failing sensor, a faulty motor, or low battery voltage. Ensure your battery is strong and inspect connections regularly.
• How often should I change the oil in my Sportsman 850? It's recommended to change the oil and filter every 25 hours of operation or every six months, whichever comes first. Always refer to your owner's manual for specific recommendations.
• Why is my Sportsman 850 hard to start? Difficulty starting can be due to a weak battery, a faulty fuel pump, or a clogged fuel filter. Check these components and ensure your battery is fully charged.
• What kind of coolant should I use in my Sportsman 850? Use the type of coolant recommended by Polaris. Refer to your owner's manual for the specific coolant specification.

The Bottom Line

The Polaris Sportsman 850 is a powerful and capable ATV, but it's not without its potential problems. By understanding the common issues and taking proactive steps to prevent them, you can keep your Sportsman 850 running smoothly for years to come. Prioritize regular maintenance and address any issues promptly to avoid costly repairs down the road.