Troubleshooting Bobcat 773: Blowing Smoke and Oil Issues

[MikePhua]

The Bobcat 773 is a versatile skid steer loader, known for its power and maneuverability on tough job sites. However, like all heavy machinery, it can sometimes experience issues that require attention. One of the common problems reported by users is blowing smoke and oil, which can be alarming for operators and mechanics alike. This issue not only impacts the machine’s performance but also raises concerns about its longevity.
In this article, we will break down the potential causes of this issue, explore how to troubleshoot it effectively, and offer tips on avoiding similar problems in the future.
Understanding the Problem: Smoke and Oil
When a Bobcat 773 starts blowing smoke and leaking oil, it indicates a potential malfunction in the engine or hydraulic systems. There are several reasons why this could happen, and it’s essential to properly diagnose the cause before proceeding with repairs. The smoke color, the presence of oil leaks, and the overall performance of the machine all give vital clues to pinpointing the root cause.
Types of Smoke

• White Smoke: Often indicative of coolant or water entering the combustion chamber, resulting in incomplete combustion. This is typically a sign of a blown head gasket, a crack in the cylinder head, or a leaking radiator.
  
• Blue Smoke: Usually points to the burning of oil within the engine. This could mean that oil is being consumed inappropriately, either due to worn piston rings, valve seals, or an overfilled crankcase.
  
• Black Smoke: Indicates an over-fueling issue, where too much fuel is being delivered to the engine, which could be caused by a clogged air filter, faulty fuel injectors, or incorrect fuel settings.
  

Oil Leaks
Oil leaks can result from multiple sources, such as gaskets, seals, or worn-out engine parts. In the case of the Bobcat 773, one of the more common causes for oil leaks is a failing valve cover gasket. Additionally, oil seals around the hydraulic pump, engine, or differential could be the culprits.
Diagnosing the Issue
Before jumping into repairs, it’s crucial to perform a thorough diagnosis. Here are the key steps to follow:

1. Check for Excessive Smoke: Determine the type of smoke being emitted from the exhaust. If the issue is primarily related to oil burning (blue smoke), this could point to engine damage, such as worn piston rings or valve seals. If it’s more related to coolant (white smoke), further inspection of the engine’s cooling system is required.
   
2. Inspect the Oil Levels: Ensure the oil levels are not too high, as overfilling can result in oil being pushed into areas where it shouldn’t be, causing leaks or excessive smoke. Conversely, low oil levels can lead to the engine running too hot, resulting in burning or leaking oil.
   
3. Look for Oil Leaks: Examine the engine compartment and surrounding areas for any visible oil stains or drips. Check areas like the valve cover gasket, oil pan, and hydraulic lines. Inspecting hydraulic lines is particularly important, as the Bobcat 773 has both engine oil and hydraulic fluid running through its system.
   
4. Test the Hydraulic System: A malfunctioning hydraulic system can also lead to excessive oil leakage. If the oil appears to be coming from hydraulic lines or seals, it may be time to inspect the hydraulic pump, cylinders, or hoses. Sometimes, a damaged hose or seal can cause oil to leak and smoke.
   
5. Compression Test: If the problem is suspected to be internal, such as worn piston rings, conducting a compression test on the engine can provide valuable insights. Low compression levels in one or more cylinders are often indicative of internal engine wear, which might necessitate a rebuild or replacement of parts.
   
6. Check the Turbocharger (if equipped): If your Bobcat 773 is equipped with a turbocharged engine, the turbocharger could be the source of the problem. A failing turbocharger can lead to oil leaks and the burning of oil, which results in blue smoke. Inspect the turbo for excessive wear or damage.
   

Potential Causes

1. Worn Piston Rings or Valve Seals: Over time, the piston rings and valve seals in the engine can wear out, allowing oil to enter the combustion chamber and burn. This can lead to blue smoke, and if left unaddressed, it can severely damage the engine.
   
2. Clogged or Faulty Breather: The breather system in the Bobcat 773 is designed to expel excess pressure from the engine. A clogged or faulty breather can cause pressure buildup in the crankcase, forcing oil out of seals and gaskets.
   
3. Overfilled Oil: As mentioned earlier, overfilling the oil reservoir can cause excess oil to be pushed into areas where it shouldn’t be. This can result in the engine burning oil, leading to smoke and potential leaks.
   
4. Faulty Gaskets or Seals: A worn valve cover gasket or oil pan seal can allow oil to leak out, which could eventually end up on hot engine parts, resulting in smoke. This is a relatively common issue that can be fixed with a simple gasket replacement.
   
5. Hydraulic System Problems: If the oil is coming from the hydraulic system, it’s possible that a hydraulic line or pump is damaged. The hydraulic system is pressurized, so any damage to the lines or seals can cause significant leaks.
   

Fixing the Problem
Once the problem has been diagnosed, the appropriate repairs can be made. If the issue is related to burning oil, replacing worn piston rings or valve seals may be necessary. For oil leaks, replacing faulty gaskets or seals can resolve the issue. In some cases, overfilling the oil can be fixed by draining the excess oil and ensuring that the oil level is within the proper range.
If hydraulic issues are suspected, inspecting and replacing damaged hydraulic lines, pumps, or seals will help resolve the problem. Regular maintenance of the hydraulic system, including checking for leaks and ensuring proper fluid levels, is crucial in preventing future issues.
Preventative Measures
To avoid similar issues in the future, it’s essential to perform regular maintenance on your Bobcat 773:

• Change the Oil Regularly: Follow the manufacturer’s recommendations for oil changes and ensure the correct type of oil is used.
  
• Monitor Oil Levels: Keep an eye on oil levels, making sure they are not overfilled or running too low.
  
• Check for Leaks: Regularly inspect the machine for signs of oil leaks and repair any issues promptly to prevent further damage.
  
• Hydraulic Maintenance: Regularly inspect the hydraulic system for leaks and check hydraulic fluid levels.
  

Final Thoughts
Blowing smoke and oil from a Bobcat 773 is an issue that can arise for several reasons, but with proper troubleshooting and prompt repair, it can be addressed effectively. By carefully inspecting the machine’s engine, oil levels, and hydraulic systems, operators can diagnose and fix the problem to ensure the continued longevity of their skid steer. Regular maintenance and vigilance are key to preventing this issue from recurring, keeping the Bobcat 773 running smoothly for years to come.