090G gear case breather hole

[weenieroaster]

I inherited this little used Stihl 090G (photos) when my logging buddy died. I think it is a beautiful saw, use it now and again, both for felling and milling. I still use the original loop of 1/2" chain that came with the saw. I love the sound of it popping away with that tiny muffler on there........it's just a great tool. One thing though, it had this small breather hole in the gear case cover, was manufactured that way. I think it originally came with a small cotter pin inserted into the hole, and bent over inside. Whenever the saw is run on it's side, like in normal felling operation, gear oil drips out the hole. As the saw gets hot and the oil becomes less viscous, the hole leaks more and more. I don't have the saw's manual, it must say something about it in there? I have wondered what Stihl had in mind by that hole placement.

I bored a hole lengthwise through a small threaded stud, and fastened it to the case through the enlarged and tapped breather hole, then put a small piece of gas hose with a bit of fuel filter material in it over the stud (photo). It still dribbles a bit of oil out after the filter material becomes saturated, I think the heat forces it out, but it's an improvement over the plain hole. Originally I had put a small screw in the stub of gas line, like in a fuel tank breather, but the filter material seems to work best.

Has anyone dealt with this leaking problem, or seen any Still literature on the situation? Any additional considerations?

Thanks for the help.

 

[belgian]

that's a real beauty saw, congrats !

I have no ipl of this saw, but I assume the hole we're talking about should be a venting valve for the gear oil tank. Bill G might help you out on this one.

 

[weenieroaster]

Thanks belgian! The degree of finish and attention to detail on the saw are very nice, it has a "handmade" look to it. I understand that when my friend wanted to order the saw here, in those days they had to special order it from Germany, and it cost him a small fortune. The income from tree removals was also good then, especially when a big Zelkova came along that you could sell. It is a much prized wood that everyone wanted, and sawmills would lay down big yen for one.

Yes, the hole is for venting the gear tank. There is a good quantity of oil in there.

 

[Bill G]

I will try to post a picture of a late model 090G with the cotter pin. I also have other older 090G saws and they all have the cotter pins in them. I am not sure why the the hole was increased in yours. The part number for the pin is 9395 021 0790. It is 1.5mm diameter and 12mm in length The retail US price is $0.99,

Thanks,
Bill

 

[Podaltura]

Weenie:

Can you put any pictures working in Japan whit this beast? Or other chainsaws? I´m interesting in the Japanese logging and arborist works.

Thanks

 

[weenieroaster]

Thanks Bill. Actually, I enlarged the hole myself for the threaded stud insert arrangement, after I felt the need to try and reduce the leakage past the cotter pin. As I mentioned, it is an improvement. I hesitated to mess with the saw and depart from the original details, but the leaking always bothered me. Do you find any leaking out on your saws at that breather hole? My guess is that Stihl just figured that the amount of oil coming out isn't much of a concern, if you keep an eye on the oil level, all breather blow-by holes leak a bit of oil basicly. I was using the saw for milling at one point, so the powerhead would spend a lot of time on it's side with the gear case facing down. After a whole day like that, I would lose a far amount of oil.

Bill, do you know what the max rpm setting should be on the G? The Tillotson carb has a governor arrangement on it, currently at the lowest setting. It came that way from the factory I can tell, the lead solder is still on it. I wouldn't mind kicking up the revs a bit if within the max. In this case, I'd definitely get a tach before attempting it though. What pitch chain are you running? Thanks!

Podaltura, I can try and post some pics along the way. Thanks for asking.