Vent Insert for 028 AV WB

[DanAyo]

I am cleaning up an 028 Super AV WB. The fuel tank vent insert is missing. The part number is “Stihl 1120 358 8105 vent insert”.

Can I use the cut off threads of an old screw that can be pushed into the line? Looks like the screw threads will allow the gasses to vent through them.

 

[Vintage Engine Repairs]

I am cleaning up an 028 Super AV WB. The fuel tank vent insert is missing. The part number is “Stihl 1120 358 8105 vent insert”.

Can I use the cut off threads of an old screw that can be pushed into the line? Looks like the screw threads will allow the gasses to vent through them.

Yep, they use a grub screw but either screw will work. Make sure it’s not an overly tight fit in the tube either. Pull a vacuum and test that it bleeds fairly quickly back down.

 

[cookies]

I hate those styles of vent since they easily allow fuel and fuel vapors to leak out esp when the saw is stored in a hot building or set in the sun. I change every one that comes across my bench to a section of tygon and a barbed check valve. I have even started doing it to the saws that have the flap valve mounted inside the tank that presses into the vent hole. They seem to get crud build up between them and the tank and get stiffer after a few years reducing their sealing.
I like folks to be able to toss their favorite saw behind the seat and not get gassed out of their truck or van or find their garage/enclosed trailer wreaking of gasoline...wives really hate it or at least mine raises hell about it!

 

[Mad Professor]

I hate those styles of vent since they easily allow fuel and fuel vapors to leak out esp when the saw is stored in a hot building or set in the sun. I change every one that comes across my bench to a section of tygon and a barbed check valve. I have even started doing it to the saws that have the flap valve mounted inside the tank that presses into the vent hole. They seem to get crud build up between them and the tank and get stiffer after a few years reducing their sealing.
I like folks to be able to toss their favorite saw behind the seat and not get gassed out of their truck or van or find their garage/enclosed trailer wreaking of gasoline...wives really hate it or at least mine raises hell about it!

The ones in my 038s lasted > 30 years and never gave problems until the hoses disintegrated from age, and/or new fuels.

Don't fix what's not broken. Three feet of good line will service a fleet of saws for years if you don't lose the screws.

When you replace the grub screws, push them in, not screw them. Screwing them cuts threads into the line and prevents venting.

 

[HarleyT]

I just go back with one of those cheap little echo vents.

 

[cookies]

The ones in my 038s lasted > 30 years and never gave problems until the hoses disintegrated from age, and/or new fuels.

Don't fix what's not broken. Three feet of good line will service a fleet of saws for years if you don't lose the screws.

When you replace the grub screws, push them in, not screw them. Screwing them cuts threads into the line and prevents venting.

Even using new line they leak gas if the saw is laid on its side and vent gasoline vapors into the air with pressure changes, like you said its a 30 year old design.
@HarleyT Thats exactly what I use too

 

[Scrapcan]

Aren't there supposed to be two grub screws at two locations? I seem to remember two measurements for setting them in the shop manual

 

[Mad Professor]

Even using new line they leak gas if the saw is laid on its side and vent gasoline vapors into the air with pressure changes, like you said its a 30 year old design.
@HarleyT Thats exactly what I use too

I'll set one of my 038s on it's side with full tank and report back

 

[Mad Professor]

Aren't there supposed to be two grub screws at two locations? I seem to remember two measurements for setting them in the shop manual

Yes. 028/038 took 2.

 

[Wood Doctor]

Here's another discovery that I ran into with a Stihk MS 290 that caused a shutdown when restarting. The tank vent was blocked completely with a nail that somebody taper shaped and pounded into the tank's vent opening. It was hidden from view. Then the short hose was attached with the typical threaded screw on top. The combination of the tapered nail and the threaded screw completely blocked the venting of any fuel fumes. Restarting the warm engine thus became almost impossible.