Chainsaw Leaking Bar Oil

Wondering why all of a sudden, your craftsman chainsaw leaking bar oil? Well, that’s a widespread problem with all the chainsaws out there, and there are several reasons for that. 

But the most common one is the incompetence of the valve towards holding the negative pressure.

When the valve is out of order or cannot control the negative pressure, that causes a significant oil leak. However, that’s one of the reasons; check out below to find more. 

Possible Causes of Craftsman Chainsaw Leaking Bar Oil

Valve unable to manage negative pressureRepair or replace the valve.
Sawdust and residue buildupGetting rid of sawdust and residue buildup.
High oil pressurePressure adjustment
Worn out the rubber ringInstalling a new rubber ring.
Faulty oil tankReplace or repair the oil tank. 

We have come up with 5 reasons why your chainsaw might be leaking oil and quick fixes. We’ll be going through all of them one by one, so buckle up and read through. 

Faulty Valve 

In case you don’t know, the valve is a thing that draws air to the inner direction in order to let the oil pump out properly. It is what is responsible for the oil tank’s negative pressure. The valve maintains the negative pressure so we don’t notice any leak. 

But when the valve doesn’t work properly, it can’t maintain the negative pressure, leading to an oil leak. And since oil travels to the bar and chain through this valve, anything wrong with it will leak a good amount of oil. 

Even though there are a few reasons why the negative pressure isn’t maintained, the most common reason is a faulty valve. Either the valve is worn out, or it has gone out of line, or it is jammed. 

Solution: If you are using low-quality oil, then there is a high chance that the valve will be jammed sooner or later. And if that’s the case, you just have to open and clean the valve. 

And if you find the valve has worn out, it is best to replace that with a good-quality valve. Newcomers might not be able to do that on their own, so we suggest contacting an expert. 

Sawdust and Residue Buildup 

If you are using your chainsaw on regular basis then it is pretty obvious that the machine will be covered with sawdust. 

And sometimes the dust gets inside the engine and oil filter, which we don’t notice. Dust tends to get inside more when you are chopping trees or lumber with the chainsaw. 

When the dust gets inside the oil filter, it jams it and doesn’t allow it to work normally. And as a result, the chainsaw bar leaks oil. Not only that, but when the oil filter gets jammed, you might even notice your chainsaw not working properly. 

However, if the leaking is happening from the dust buildup, don’t worry; it is straightforward to fix. Here is exactly what you would want to do…

Solution: You would also need to open the chainsaw with the needed tools. Locate the oil filter, which should be near the oil tank. And check if it is jammed. 

If you see dust buildup there, take something pointy like a pen and try to get rid of that buildup. Be careful, do not damage the filter. 

Once you have broken the buildup, take a brush and wash the filter properly. And then install the filter back to where it belongs. That should solve the leaking problem. 

Pressure Buildup

Excessive pressure on the oil tank is another reason why the chain, bar, and other areas of a chainsaw leak oil. 

Due to long use without maintenance, it is pretty common for chainsaws to have extra pressure on the tank. And the higher the pressure, the more oil the machine will leak. 

Solution: It is straightforward to fix. All you need to do is get rid of that extra pressure. And to do that, you will have to unscrew the oil cap, which should do the work.

Unscrewing the oil cap will release the air that causes extra pressure, and things will go back to normal again. 

Worn out Rubber Ring

The oil tank reservoir and the chain has a rubber ring in between; the purpose of that ring is to prevent leak. But when the rubber is shrunk or worn out, that can cause an oil leak on the bar. 

Solution: Rubber rings are cheap; if you find anything wrong with the rubber ring, it will be best to replace it. 

Leaked Oil Tank 

If your chainsaw is very old and you don’t find any reason for the oil leak, then it is probably the oil tank itself. Oil tanks get rusty over time and can cause leaks. So at the end of all kinds of checking, you would want to give a thorough check on the oil tank to see if that has any leaks. 

Check all the sides of the tank closely, and try to find cracks. If you find any crack on the tank, that’s what is leaking the oil. 

Solution: You can weld the oil tank to fill the cracks or holes so that it won’t leak oil anymore. But it would be wise if you could change the entire tank. When the tank gets old and rusty, it tends to show cracks in different areas. So it is better to get rid of the old one and get a new one installed.

A Helpful Tutorial You May Need!

Frequently Asked Questions (FAQs)

How To Store A Chainsaw So It Doesn’t Leak oil?

Ensure the oil reservoir is empty and if not, drain all the oil before storing the chainsaw. Then secure the plugs and put a towel underneath the chainsaw to capture the tiny amount of oil coming from the chain.

How Do I Stop My Craftsman Chainsaw From Leaking Oil?

The only way to stop your chainsaw from leaking oil is to find out the problem and fixing it. The most common reasons are dust buildup, faulty valve, and increased pressure on the tank.

How Do You Adjust The Oiler On A Craftsman Chainsaw?

Craftsman chainsaws come with an oil adjustment screw. Tighten the screw with any flathead screwdriver to lower the oil flow and vice versa.

Why Is My Chainsaw Leaking Bar Oil When Sitting?

The most common reason for this is using oils with less viscosity. In other words, using thin oil. As we all know that the chainsaw chain gets lubricated by the oil when working. If the oil is thin, it starts to drip when the machine is sitting.

Why Is My Chainsaw Leaking Bar Oil When Not In Use?

It could be the increased pressure on the oil tank or a jammed oil filter. And it could also be the leftover oil on the chain that is dripping.

How Do Craftsmen Chainsaw Bar Oil Adjustments?

Do you see the half-circle notch on your chainsaw? Right 1-inch under that, you should see a screw which is the oil adjustment screw. If you loosen the screw, it will increase the oil flow. And tightening it will lower the oil flow.


These are probably the reasons why your craftsman chainsaw leaking bar oil! There could be other reasons, but those mostly don’t lead to oil leak issues exactly.

However, if you are unable to find out why your chainsaw is leaking oil, let us know in the comment section.

By admin