Why Chainsaws Leak Bar Oil when not in Use?

If you notice that your chainsaw is leaking when it’s turned off, there could be two main reasons.

The first one is if the oil tank is overfilled; this will cause pressure buildup inside of it which causes some to flow out through various ports in the chainsaw or the engine housing.

Another possibility would be small punctures along the oil lines or an issue with the oil pump.

To troubleshoot, try checking the tank’s fill level and ensuring that it is not overfilled. If this doesn’t solve the issue, then it may be necessary to check for any punctures in the lines or a malfunctioning oil pump, and potentially replace those parts if necessary.

It’s always important to keep an eye on your chainsaw’s oil levels and change it regularly to prevent any potential leaks or malfunctions.

When a chainsaw is not in use, it’s important to regularly oil the moving parts of your machine. Oil will keep everything running smoothly and prevent corrosion from setting into place which could lead to leaks or other damage when you need that extra power most.

Let’s now look in more detail at the different potential issues:

Overfilled oil tank

When the oil in your chainsaw gets too warm, it can expand and seep into various parts of its assembly. This is especially common with limited storage space where temperature changes are frequent or extreme differences between day/night time periods.

To prevent this, make sure to always check and follow the manufacturer’s guidelines for your chainsaw’s fill level.

The first step in solving this issue is checking the fill level and ensuring that it is not overfilled. If necessary, drain some of the excess oil until it reaches a safe level.

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Any excess pressure buildup can cause leaks, so be careful not to overfill the tank. Additionally, ensure that there is proper ventilation of the tank by keeping it away from direct sunlight or heat sources.


Oil lines can become punctured from external damage, such as if your chainsaw were to hit a rock while cutting through wood. This can also occur with wear and tear over time, especially if the machine is not properly maintained and lubricated.

To troubleshoot this issue, inspect the oil lines for any visible damage or punctures if you notice that there is a significant amount of oil buildup below your chainsaw.

To investigate further, remove both covers and check for any cracks or breaks in the oil lines.

Before installing the new oil line, make sure to empty the oil reservoir. You will need to remove the engine mounting nuts and bolts (if there are any) in order to access the old line. Pry it out of its hole using a flathead screwdriver and then replace it with your new one before reconnecting all of the pieces you removed.

Malfunctioning Oil Pump

A malfunctioning oil pump can lead to excessive or inadequate lubrication of your chainsaw’s moving parts, and can also result in oil leaks.

If you suspect that the issue is with your oil pump, it may be necessary to replace it entirely.

To do so, first empty out the oil reservoir before removing its cover and disconnecting the hose leading from the pump to the tank. Next, remove any mounting bolts and screws that hold the pump in place, and then replace it with a new one before reconnecting all of the components and filling up the tank with oil.

It’s also important to regularly change your chainsaw’s oil as recommended by the manufacturer, to prevent any potential buildup or malfunctions within its assembly.

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Poorly Vented Tanks

Another reason for oil leakages that is often overlooked is poor ventilation in chainsaw oil tanks. To avoid a vacuum forming, chainsaw oil tanks should be properly ventilated so that air pressure can equalize between the tank and the atmosphere.

Most tanks come with a one-way valve to allow air to flow into the tank as needed; however, when the temperature changes dramatically, this system may fail and lead to rapid changes to the air pressure inside the tank, causing leaks.

At night, for example, the air pressure in a chainsaw oil tank will decrease due to lower temperatures. This will allow outside air to enter the tank and equalize the pressure. As temperature rises during the daytime, so does air pressure inside the tank since the valve only works one way; thus, balance can only be maintained by excessive oil leaking from ports.

It is worth noting that this is a trend that is often seen in areas that have large temperature fluctuations between day and night.

To prevent this issue, regularly check for any clogs in the one-way valve and ensure that it is functioning properly. Additionally, avoid storing your chainsaw in extreme temperatures or direct sunlight as this can also cause pressure changes within the oil tank.

Do chainsaws always leak bar oil?

When using your chainsaw, it is normal for a few drops of oil to leak. This happens because the chain needs to be lubricated as it moves around the guide bar. The oil pump helps deliver a steady flow of bar oil to keep the chain – and you – safe while you’re working.

However, if you’re experiencing excessive leaking or a sudden increase in oil leakage, this could indicate a problem with your chainsaw’s lubrication system.

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It is important that before you start up your chainsaw, you inspect the guide bar and check for any breaks or cracks that may be causing excess oil to leak out. You should also get in the habit of checking the bar oil reservoir and making sure it is properly sealed to prevent leakage.

In addition, if you notice that your chainsaw needs to be topped up with oil at an unusually rapid rate, it may be time to check the oil pump and its delivery system for any malfunctions or clogs.

Overall, while a small amount of bar oil leaking is normal during use, excessive leaking can indicate a potential issue that should be addressed to avoid further damage to your chainsaw.

How often should you add bar oil to a chainsaw?

Remember to top up the bar oil reservoir for each tank of fuel you add to your chainsaw. For optimal performance, it is recommended to check the bar oil level before each use and top up as necessary.

Also, be sure to regularly change out the bar oil according to manufacturer instructions.

This will ensure that your chainsaw’s lubrication system remains in good condition and helps prevent excess leakage. Note that using a high-quality bar oil can also potentially prolong the lifespan of your chainsaw’s guide bar and chain.

If you are not sure of the correct type or amount of bar oil to use for your chainsaw, consult the manufacturer’s guidelines or speak with a professional at a chainsaw shop. Keep in mind that using the wrong type of oil or too little oil can cause damage and decrease the efficiency of your chainsaw.

Overall, proper maintenance and care are key to keeping your chainsaw running smoothly and safely. Regularly checking and maintaining the bar oil levels is just one aspect of this upkeep.