mtngun
Addicted to ArboristSite
Our Aussie friends don't seem to like the air filter design on the big pro Stihls. I guess Aussie wood is like kryptonite, except harder and more abrasive ? 
Anyway, I agree that there are some issues with the Stihl design, particularly with the seal.
I do a lot of milling, which generates fine dust rather than big chips. Plus, the saw is close to the ground, at times rubbing against the pile of dust, so you know it's going to get dirty. And just because it's softwood, don't think the dust isn't abrasive -- if the filter is leaking, the dust can fry the top end after just a few hours cutting -- as I learned the hard way.
Filter after 2.2 hours run time milling doug fir (my CSM has an hour meter built into the onboard tach
). I've seen far worse, but the point is, it's covered with very fine dust.........
........ yet the inside is squeeky clean. (the one or two specs you see fell off the outside of the dirty filter as it was being removed). I'm skeptical that that dust actually leaks THROUGH a Stihl filter, unless the filter is torn. But, I know from bitter experience that, as it comes from the factory, dust may leak AROUND the filter, at the seal.
For one thing, by design, not by accident, the screw knob that secures the filter assembly bottoms out on the shoulder of this stud, where the arrow is pointing....... even if the filter seal isn't pushed tight. It doesn't do any good to reef on the screw knob with a scrench, because you are just reefing against this stud shoulder, not against the filter seal. I don't understand why they designed it that way. I don't like it. I don't trust it.
Solution: carefully file the shoulder back, using a safe-edge raker file. It should only take about 0.010" or so. The goal is to be able to keep turning the screw knob until the filter seal is tight, without the stud shoulder botching things up.
Another thing that can go wrong, if you are using the hard plastic inner baffle, is that, depending on the tolerance stack, the assembly may bottom out on the hard plastic inner baffle before the filter seal is tight.
Solution: use the foam inner baffle instead.
Another thing that can go wrong, if you are using the Bailey's clone of the Stihl filter, is that the depth of the clone filter seems to be about 0.005" or so less than the depth of an OEM filter. That makes the tolerance stack that much worse, that much less likely to seal.
This is all dependent on the tolerance stack of your particular saw, so depending on the tolerances, one Stihl saw may not have any problem at all with the filter seal, while the next Stihl saw may leak a lot.
Before I knew these things, I lost a top end in just a few hours, while running the Bailey's clone filter with the OEM hard plastic inner baffle (in fairness to Bailey's, they sell the clone with a foam inner baffle).
Since modding the stud shoulder and tossing the hard plastic baffle, there is zero leakage with either the OEM or the Bailey's clone. Zero. No visible trace of dust past the filter.
As for how often to clean the filter, I start the day with a clean filter, run it all day, and then clean it when I get home. Sometimes the filter is pretty filthy at the end of the day, yet since doing the mods, there is zero leakage.
Unlike some other saws, I've never noticed a loss of power from running dirty filter on the 066. The carb compensator seems to do its job.
Anyway, I agree that there are some issues with the Stihl design, particularly with the seal.I do a lot of milling, which generates fine dust rather than big chips. Plus, the saw is close to the ground, at times rubbing against the pile of dust, so you know it's going to get dirty. And just because it's softwood, don't think the dust isn't abrasive -- if the filter is leaking, the dust can fry the top end after just a few hours cutting -- as I learned the hard way.
Filter after 2.2 hours run time milling doug fir (my CSM has an hour meter built into the onboard tach
). I've seen far worse, but the point is, it's covered with very fine dust................. yet the inside is squeeky clean.
(the one or two specs you see fell off the outside of the dirty filter as it was being removed). I'm skeptical that that dust actually leaks THROUGH a Stihl filter, unless the filter is torn. But, I know from bitter experience that, as it comes from the factory, dust may leak AROUND the filter, at the seal.For one thing, by design, not by accident, the screw knob that secures the filter assembly bottoms out on the shoulder of this stud, where the arrow is pointing....... even if the filter seal isn't pushed tight. It doesn't do any good to reef on the screw knob with a scrench, because you are just reefing against this stud shoulder, not against the filter seal. I don't understand why they designed it that way. I don't like it. I don't trust it.
Solution: carefully file the shoulder back, using a safe-edge raker file. It should only take about 0.010" or so. The goal is to be able to keep turning the screw knob until the filter seal is tight, without the stud shoulder botching things up.
Another thing that can go wrong, if you are using the hard plastic inner baffle, is that, depending on the tolerance stack, the assembly may bottom out on the hard plastic inner baffle before the filter seal is tight.
Solution: use the foam inner baffle instead.
Another thing that can go wrong, if you are using the Bailey's clone of the Stihl filter, is that the depth of the clone filter seems to be about 0.005" or so less than the depth of an OEM filter. That makes the tolerance stack that much worse, that much less likely to seal.
This is all dependent on the tolerance stack of your particular saw, so depending on the tolerances, one Stihl saw may not have any problem at all with the filter seal, while the next Stihl saw may leak a lot.
Before I knew these things, I lost a top end in just a few hours, while running the Bailey's clone filter with the OEM hard plastic inner baffle (in fairness to Bailey's, they sell the clone with a foam inner baffle).
Since modding the stud shoulder and tossing the hard plastic baffle, there is zero leakage with either the OEM or the Bailey's clone. Zero. No visible trace of dust past the filter.
As for how often to clean the filter, I start the day with a clean filter, run it all day, and then clean it when I get home. Sometimes the filter is pretty filthy at the end of the day, yet since doing the mods, there is zero leakage.
Unlike some other saws, I've never noticed a loss of power from running dirty filter on the 066. The carb compensator seems to do its job.
