Chainsaw Oil cap leaking

dognose

Silver Member
Apr 15, 2009
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Fisher F70
My CS400 oil reservoir cap is leaking oil.

It looked like the o-ring was smashing out of round when the cap tightened. The saw is about 5 years old and I cut a lot of trees for firewood. I clean my saws regularly. I heat 95% with a regency wood stove.


I replaced the o-ring and sat the saw in a way to test the repair. An hour later oil had leaked out.

Any ideas for fixing this issue?

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Maybe the cap is defective. Or just store it fill cap side up. Overall I'd need to look at it inorder to have any idea on how to remedy the problem. I cut a lot of wood living in Buena Vista Colorado. All my heat was wood and coal at times I'd get from a buddy that would run his two ton dump truck over to Paonia, Colo and pickup from the mine sizable lumps that would burn all through the night. I had a 26" Jonsered saw for all my cutting.
 

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Are you sure you used the correct o-ring? There are a lot of variables available. The ID, OD, thickness and material all need to be right.
Good luck
 

Now that is a pain when they leak, I have had issues with the Stihl pole saw leaking, but never my Echo saw.

Have you checked the air vent/oil line? If clogged the reservoir can build up pressure and cause a leak.
 

Go on EBay buy the part you need from cap to the whole tank.We cut mountains of wood and are always breaking saws.I find parts for our saws on there all the time for reasonable price.
 

Is it leaking out of the fill tube ? Or the inside seal ?
 

there are 2 0il seals on a chain saw. The one O ring seal stops the oil from leaking out the fill port. The inside one regulates how much oil is applied to the chain while it is running. When the saw is running it should create a fine mist for oiling the chain. Start your saw up and hold it near a piece of cardboard and see how much is sprayed on the cardboard. You need to determine when the leak is coming from . If this makes sense :)
 

Hi Dognose
This is a common occurance with chain saws.
I need to fix mine.
Here is one of many fixes on you tube.
 

My CS400 oil reservoir cap is leaking oil.

It looked like the o-ring was smashing out of round when the cap tightened. The saw is about 5 years old and I cut a lot of trees for firewood. I clean my saws regularly. I heat 95% with a regency wood stove.


I replaced the o-ring and sat the saw in a way to test the repair. An hour later oil had leaked out.

Any ideas for fixing this issue?

View attachment 2121434
One thing going for saw is it is not a Poulan..had one stop running one day so opened gas cap and was sprayed in face by boiling hot mixed gas..I would check plastic housing and O-ring for hairline cracks.
 

I had one that leaked as well and turned out to be the plug had somehow gotten out of round just enough to leak, but not enough to inhibit its screwing into the saw.
 

I have had guys say that they crack the filler cap after they shut off the saw and it cools.
For some reason it builds up pressure, even though it still oils the bar/chain.
Known guys that lay the saw on its side, to prevent this from happening.
 

I currently have 3 operating saws ( because I hate it when my day is shut down by equipment failure. Chain saws have many ways to fail.) There have been many predecessors. They all leak. Always have and always will. I store/transport them with the leaks in mind. They won, I surrendered. I am at peace with my approach.
 

I currently have 3 operating saws ( because I hate it when my day is shut down by equipment failure. Chain saws have many ways to fail.) There have been many predecessors. They all leak. Always have and always will. I store/transport them with the leaks in mind. They won, I surrendered. I am at peace with my approach.
They kind of have a habit of drooling about.
3 saws, I have 3 also. Mainly use the 2, one to get pinched, and the other to unpinch the other.🤣
 

its definitely coming from the cap, I have 3 other echos with no issues. I have taken to laying it on its side most of the time to prevent the leak. Its the correct O ring.
Its not a major issue, just an annoying issue.
 

the cap is likely cracked , take it off and hold it to a very small flashlight in a dark room and see if light comes through.
look where you put the screw driver ,that's where mine cracked one cold morning.
 

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