How to Replace Glow Plugs on a Bobcat 863 Skid Steer Loader

[MikePhua]

The Bobcat 863 Skid Steer Loader is a versatile and reliable piece of equipment used in a variety of construction and landscaping tasks. Like many diesel-powered machines, it relies on glow plugs to aid in the cold-starting process, ensuring the engine runs smoothly in low temperatures. If your Bobcat 863 is experiencing hard starts or running rough, it could be a sign that the glow plugs are worn out or malfunctioning. Replacing the glow plugs is a relatively simple maintenance task that can make a big difference in the performance of your machine.
Understanding the Role of Glow Plugs
Glow plugs are essential components in diesel engines, especially during cold starts. Diesel engines do not have spark plugs like gasoline engines. Instead, they rely on high compression to ignite the air-fuel mixture. However, when the engine is cold, the air inside the combustion chamber is not hot enough to ignite the fuel. This is where glow plugs come into play. They are electric heating elements installed in each cylinder of the engine.
When the engine is cold, the glow plugs heat up to high temperatures to warm the air in the cylinders, facilitating easier ignition of the fuel. In addition to cold-starting, they help maintain smooth operation when the engine is at low idle speeds or in extreme cold weather conditions.
Signs of Faulty Glow Plugs
A few common signs that your Bobcat 863 might have a glow plug issue include:

• Hard Starting: The most obvious symptom is difficulty starting the engine, especially in cold weather. If the engine cranks but doesn’t start easily, it could be due to failed glow plugs.
  
• Rough Idle: If your Bobcat 863 runs roughly when idling, it could indicate that one or more glow plugs are not functioning properly.
  
• Excessive Smoke: Unburnt fuel can accumulate in the exhaust, leading to excessive white or black smoke, especially during the initial moments after starting the engine.
  
• Check Engine Light: Some models will display a "Check Engine" light or error code related to the glow plug circuit if there's an issue.
  

How to Replace the Glow Plugs on the Bobcat 863
Replacing the glow plugs on a Bobcat 863 is a straightforward process that requires basic tools. Here’s a step-by-step guide to help you with the replacement.
Tools Needed

• Socket wrench set
  
• Extension bar for reaching deep components
  
• Glow plug socket (or deep socket)
  
• Torque wrench
  
• Anti-seize lubricant
  
• Replacement glow plugs
  

Step-by-Step Guide

1. Preparation
   • Start by ensuring that the Bobcat 863 is on a flat surface, and the engine is off.
     
   • Wait for the engine to cool down before proceeding, as working with a hot engine can cause burns or damage.
     
2. Disconnect the Battery
   • Always disconnect the negative terminal of the battery before working on any electrical components. This will prevent accidental short circuits and electrical shocks.
     
3. Locate the Glow Plugs
   • The glow plugs are typically located along the cylinder head. In the Bobcat 863, they are usually mounted near the intake manifold. You may need to remove some engine covers or components to gain access.
     
   • Consult your operator’s manual to verify the exact location of the glow plugs.
     
4. Remove the Glow Plug Wiring
   • Each glow plug is connected to the electrical system via a wiring harness. Gently disconnect the wiring from each glow plug. Be careful not to damage the connectors.
     
5. Loosen and Remove the Glow Plugs
   • Using a socket wrench with the appropriate socket, loosen and remove each glow plug. If the glow plugs are stuck due to carbon buildup, you may need to use penetrating oil and let it sit for a few minutes before attempting removal.
     
   • When removing the glow plugs, do so gently to avoid damaging the threads in the cylinder head.
     
6. Prepare the New Glow Plugs
   • Before installing the new glow plugs, apply a small amount of anti-seize lubricant to the threads. This will make future removal easier and prevent the plugs from seizing in the cylinder head.
     
   • Make sure you are using the correct type of glow plugs recommended by Bobcat for your 863 model.
     
7. Install the New Glow Plugs
   • Carefully insert the new glow plugs into the cylinder head and hand-tighten them initially to ensure they are seated properly.
     
   • Use a torque wrench to tighten the glow plugs to the manufacturer’s recommended torque specifications. Over-tightening can damage the threads, while under-tightening can result in poor electrical contact or improper sealing.
     
8. Reconnect the Wiring
   • Reattach the electrical wiring to the new glow plugs. Ensure that the connections are secure and free of corrosion.
     
9. Reassemble the Engine
   • If you had to remove any components to access the glow plugs, now is the time to reassemble them. Tighten any bolts or fasteners that were removed.
     
10. Reconnect the Battery
    • Reconnect the negative terminal of the battery and make sure everything is properly secured.
      
11. Test the Engine
    • Start the engine to ensure the new glow plugs are functioning correctly. The engine should start smoothly, without excessive cranking or rough idling.
      

Maintenance Tips for Glow Plugs
To maximize the lifespan and efficiency of your glow plugs, follow these maintenance tips:

• Regular Inspections: Periodically inspect your glow plugs, especially if you’re noticing hard starting or rough idling. Checking them early can help prevent major engine problems.
  
• Use Quality Fuel: Poor-quality fuel can lead to carbon buildup on the glow plugs, causing them to fail prematurely. Always use the recommended fuel grade for your Bobcat 863.
  
• Proper Shutdown Procedures: After using your skid steer loader, avoid shutting off the engine immediately after heavy work. Let it idle for a minute or two to cool down. This helps prevent excessive heat buildup that can damage the glow plugs.
  
• Replace in Pairs: If one glow plug fails, it’s often best to replace all of them at the same time. Glow plugs are designed to work in unison, and replacing all of them ensures balanced performance.
  

Common Glow Plug Problems and Solutions

• Glow Plug Relay Failure: In some cases, the glow plug relay may fail, preventing the glow plugs from receiving power. Check the relay and replace it if necessary.
  
• Electrical Connector Issues: Sometimes, the connectors that attach the glow plugs to the wiring harness may become corroded or damaged. Clean or replace the connectors to restore proper function.
  
• Carbon Buildup: If you’re having difficulty removing the glow plugs, it may be due to carbon buildup. In this case, use a penetrating oil and allow it to sit for several minutes before attempting to remove the plugs.
  

Conclusion
Replacing the glow plugs in your Bobcat 863 Skid Steer Loader is a relatively simple maintenance task that can greatly improve the machine's cold-starting performance. By following the steps outlined above, you can quickly and efficiently replace the glow plugs and get your machine back to full operation. Regular maintenance of the glow plugs, as well as the entire engine, will help extend the lifespan of your equipment and ensure reliable performance, especially in colder climates. Remember, always consult your Bobcat manual for specific part numbers and torque settings when replacing any parts.