Your Stihl chainsaw can leak bar oil due to several reasons, often related to the design of the oiling system or wear and tear on components like seals, hoses, or the tank itself.
Understanding the Bar Oiling System
Chainsaws have a system that automatically lubricates the chain and guide bar with bar oil as the saw operates. Oil is stored in a tank, pumped out, and flows along the guide bar groove.
As oil is used, air begins to replace the space where the oil was previously stored in the tank. This requires proper ventilation of the oil tank. If there isn't proper ventilation of the oil tank, a vacuum can occur inside the tank, which can reduce the flow of oil to the guide bar during operation. However, issues with the tank, its seals, or the ventilation mechanism itself can also lead to leaks when the saw is not in use.
Common Causes of Stihl Chainsaw Bar Oil Leaks
Several factors can contribute to bar oil leaking from your Stihl chainsaw:
- Residual Oil Drainage: This is the most common reason for oil dripping when the saw is stored. After use, some oil remains in the pump, lines, and bar groove, which can gradually drain out over time due to gravity and temperature changes. Stihl notes that a small amount of residual oil drainage after use is normal.
- Faulty Oil Tank Cap or Seal: The oil tank cap provides the seal for the tank and often incorporates a vent to allow air in as oil is used. If the cap is not tightened correctly, the seal is damaged or worn, or the vent mechanism is faulty, oil can leak from the tank opening.
- Damaged or Worn Hoses and Seals: The system uses hoses and seals to carry oil from the tank to the pump and then to the bar. Over time, these can become brittle, cracked, or loose, creating leak points.
- Cracked Oil Tank: Physical damage or aging plastic can cause cracks in the oil tank itself, leading to leaks.
- Worn Oil Pump Components: While less common for simple external leaks, wear within the oil pump or its seals could potentially contribute to leaks, especially around the area where it connects to the tank or output line.
- Storage Position and Temperature: How you store the saw can affect leaks. Storing it on its side can sometimes encourage oil drainage. Temperature changes can also cause the oil and air inside the tank to expand or contract, potentially pushing oil out through the easiest path (like a weak seal).
Preventing and Addressing Leaks
- Store Properly: Store the chainsaw level or slightly tilted so the bar is lower, allowing residual oil to drain into a catch pan rather than onto the floor or workbench.
- Check Tank Cap: Ensure the oil cap is clean, the seal is intact, and it is tightened properly.
- Inspect for Damage: Periodically check hoses, the oil tank, and seals for visible signs of cracks or wear.
- Clean the Saw: Keeping the chainsaw clean of sawdust and debris can help you spot leaks more easily and prevent damage to components.
While some minor residual oil drainage is normal after using a chainsaw, excessive leaking or leaking from areas other than the bar tip when stored suggests a specific problem that needs attention, such as a worn seal, damaged hose, or faulty tank cap.
