Fixing Chainsaw Bar Oil Problem With Air Compressor

What do you do if the bar oil stops flowing in your chainsaw? I was faced with that problem a couple of years ago so I brought the saw to a small engine repair guy and he wasn't able to fix it without buying a "special tool". My chainsaw, a Stihl MS170, only costs $200 new so I figure that pursuing outside repair further would not be worth it.

So with nothing to lose I decided to try applying air pressure to the bar oil tank using the blower output of my shop vac - the idea was to force-start the flow and, hopefully, clear out any obstruction. This actually worked! I've had to use this idea a couple of times since then and so far no problems. Once you get the oil flowing it continues to flow for a "long" time under normal conditions. I'm not sure why the oil stops flowing in the first place and I haven't attempted to dismantle the saw to find out. I assume a clot or blockage of some kind happens in the oil feed system - perhaps if the saw lays idle for a long time, I'm not totally sure about that. I made up a video on using the shop vac to fix the oil feed problems. The video has been quite popular on Youtube with over 150K views... this indicates that I'm not the only one having this problem. Here's that video: Fixing chainsaw bar oil problem with shop vac

We had a wind storm a few weeks ago and a fairly large fir tree came down right across my vegetable garden. I got my chainsaw out to cut the tree up and and remove it - that's when I discovered the chainsaw bar oil wasn't flowing (again).

So that's when I came up with the idea of using my air compressor to do the same thing as the shop vac. I had to make a little modification for this idea to work - I drilled a hole in the bar oil fill cap and self tapped a screw in the hole to serve as a removal plug. The hole was sized to accept the tip of my compressor air gun.

A couple of important points related to modifying the oil filler cap:

1. After drilling the 1/8 inch hole in the cap be sure to clean up all particles that resulted from the drilling.
2. Make sure the hole is located clear of the outside rim of the cap (see closeup). If you go too close to the cap sealing circle oil will leak from the cap.

Best to have a spare screw available in case you lose the original one.

I use my chainsaw close to my home so I have ready access to an air compressor. I've considered what I would do if I was using the saw away from home. I haven't tried it, but a 12 volt car tire inflator, might work just as well.

In terms of convenience and ease of use the air compressor idea wins over the shop vac idea. But both methods work equally for the intended purpose.