Pre 1998 Stihl 026 venting issue

[PV Hiker]

I have tasked myself to off season maintenance of our 4 Stihl chain saws for the Tahoe Rim Trail. The 026 has undergone different venting systems over the years. The tall vent on this early model I understand is bi-directional that air can go in and out of the tank. The problem is when you turn the saw tanks caps down the gas runs out of the vent.

Stihl 026 Serial Number: 2 23 393 980

In the picture below the tank housing nipple has a slot. The nipple has a dimension OD ~0.3", ID ~0.22" where the vent pushes on.

I found a Technical Documentation dated February 1, 1995 for a modification but list for serial numbers starting with X 30 976 775. So that puts my saw too old.

Looking down the nipple there is a slotted hole that looks like something should go there. On the parts break out, parts number 28 and 22 could, but the inside diameter of nipple is ~0.22" so those parts need a small diameter unless it is number 22 and pushes in from the inside of the tank.

I also read and can't find the post, where a user put a gas hose on the nipple and attached a weed wacker vent. Willing to do that if the other route is not doable. Anyone remember that post?

We can't have gas flowing out of the vent into a hot saw with the possibility of starting a fire in the forest.

Attached is some helpful information.

Thanks, Patrick

 

[farmer steve]

Part #22 more than likely. I used that on mine. It has to be pulled up from the inside of of the tank. Real PITA. It can tear so buy 2. LOL . You can get a complete IPL over in the beg for manuals thread in the chainsaw stickies.

 

[PV Hiker]

I guess ordering a couple is cheap enough to try. Looks like it allows air to enter tank but is pushed to the inside to seal off gas from leaking out. If it has worked for you with the same saw vintage should work for me.

A user might have lost it while cleaning and did not know what it was or not seen it go if that part was in there.

I have a manual for the 026 in PDF format. Found it in a post searching.

Thanks for your help.

 

[TLG]

Pull it up slow and easy with some pb Blaster as Farmer Steve said they tear easily.

Sent from my XT1635-01 using Tapatalk

 

[PV Hiker]

So your 026 have a serial number lower than X 30 976 774 ?

The manual shows what I believe is part 22 for the later serial numbers from X 36 348 620

Just want to confirm you used this part on a earlier serial number with success.

Patrick

 

[TLG]

Patrick, I'm glad you posted that service info. As I've seen them both ways but had not info to copy and paste. Good job on that post
Tim G.

 

[farmer steve]

Patrick valve #2 is the one I used. My Stihl mechanic said that was the only one available. In your pic it says valve 1 has been replaced by #2. When you go to your dealer take both part #s and have them look them both up. See what they say.

 

[PV Hiker]

Thanks... If you could look at your serial number as there were different tanks. There has been 4 different vents over the years.

Just talked to my dealer, very sharp, and have called different shops looking for a person that has been around and have knowledge for this very early 1990 to 80's saw. He is working hard doing research.

Does not seem that #28 would fit down from the top with the ID being ~0.22" in the tube. But would have to order part to confirm.

He was told that #22 would not fit from the inside as the tank casing thickness and slot would not allow a proper fit.

Don't want him to just order part 22 to try. That is why it would be good to know if success was had with a early serial number before X 30 976 774.

 

[farmer steve]

my saw doesn't have a serial # It was ground off. My brother found it in a ditch. Local police had no reports of a stolen 026. They stihl have my # just in case . that was 5 years ago. That being said my saw is the same as yours with the red on/off/choke lever. These were the early versions of the 026. It was switched to a black lever but i'm not sure when.

 

[PV Hiker]

Good information about the red handles. Not sure either the production dates were. If you have time and the saw, might you take some calipers and obtain ID and OD of the vent nipple? I'm thinking if tall vent with red handle and your ID, OD measurement match... then I'll have my dealer order a couple part number 22 and give it a try.

I do appreciate your time and information.

 

[farmer steve]

@PV Hiker . Don't have calipers. I'll take a pic of the saw in the morning when i go to the shop.

 

[PV Hiker]

Thanks!

 

[TLG]

Patrick, Here is one I'm working on. Two step hole as shown with caliper measurements. Small 12mm for sintered filter and larger 14 mm for the cover. Part numbers on tags for reference if needed. I see my duckbill hole isn't slotted like yours. Hope this helps a little. Didn't realize that model used so many breather configurations. Sorry but I can't read the serial number either. But for as old as these saws are who is to say if it's an original tank. LOL!!!

Sent from my XT1635-01 using Tapatalk

 

[PV Hiker]

TLG that is great information. On the parts diagram in the first post above, you have part numbers:

23 - Filter ( 1121 358 1800)
24 - Cap (1121 358 2500)
28 - Valve (4114 353 1600)

That all goes together and matches your tank and you have black handle for controller as mine is red. It helps a lot!

Can you give me a diameter measurement of the Valve (4114 353 1600) small black one? Picture of it from the backside close up? I suspect it is larger than 0.2".

I don't think that yours will work and I think #22 would be better.

Thanks.....

 

[TLG]

I'll have to measure that up tommorow night Patrick. Done in the shop for the evening. I do believe the valve you need is orange and does insert from top down. Again I'm no expert but have seen tanks like yours for sure. And the OD on the black valve is too small to cover your slots. Talk tomm. TLG

 

[SteveSr]

I don't think that yours will work and I think #22 would be better.

#22 is what they call the "mushroom" valve. The head should be big enough to cover the slot in the tank. The possible issue is that the retaining ridge is too small to hold it in the center hole.

Your saw may have come with only the upright vent. Did you check to make sure that the grub screw is still installed in your original vent? If missing it would probably leak a lot. If there it may still seep more than you want. These were kinda leaky as no one expected saws to be carried sideways.

 

[PV Hiker]

Thanks Steve. Yes the upright vent took it apart and cleaned and has the grub screw. You are correct that it came with just the vent as is from factory. But wow a lot of gas comes out. Not a seep, but constant heavy drip.

That is the concern that part number 22 may cover the slots but may not have the right grip or depth to keep it in to work properly. My Stihl guy did mention that.

Good feedback... Patrick

 

[SteveSr]

Thanks Steve. Yes the upright vent took it apart and cleaned and has the grub screw. You are correct that it came with just the vent as is from factory. But wow a lot of gas comes out. Not a seep, but constant heavy drip.

That is the concern that part number 22 may cover the slots but may not have the right grip or depth to keep it in to work properly. My Stihl guy did mention that.

Good feedback... Patrick

Stihl really liked these grub screw vents either in hard plastic like yours or inside a piece of fuel hose in their consumer saws. Then the EPA came along and didn't want unburned hydrocarbons escaping into the atmosphere. So nw the new vents are designed to onle let air into the tank and not let vapors out.

About your only option is to glue (maybe harder than it looks in plastic) a piece of tubing or small (hobby store?) hose barb and then using a new style Echo or Stihl duckbill valve.

 

[PV Hiker]

SteveSr good suggestions....look into those duckbill valves. This vent is beyond the vapor state and not sure just to purchase a new replacement tall one. Don't have faith with part 22 will match the slotted hole diameter, but see what farmer steve has.

I did find Ax-man posting for "025 tank vent mod" https://www.arboristsite.com/community/threads/025-tank-vent-mod.334694/ where he used a Shindawai T272 trimmer breather on a gas line. Ax-man's image attached.

I can see doing this but question would be is that breather (and all vent breathers of new) only one way air flow? If so would the 026 gas tank become pressurized and would gas be pushed up the fuel line and out the carburetor? That saw was designed with a two way vent and have people had any problems with pressurized tanks as they were never in a pressurized condition. ( yea there is the engineer coming out and thinking too hard.)

With multi users better to leave it stock or in a bullet prof state. Somebody will mess with it and there becomes a problem.

If the tank becomes pressurized and the carburetor does not leak, than the newest vent part number 16 / 17 would be cool to modify the tank to install somehow. Not paying $100 for new tank and handle.

 

[PV Hiker]

I might add that I located another posting in searching. HarleyT was very helpful here with images and technical bulletins.... https://www.arboristsite.com/community/threads/stihl-026-tank-vent-question.329071/

In it is a image of part number 22 vent in the proper hole. The diameter of the upper flare does not look large enough diameter to stay in my hole. Attached my image next to it.

So three choices:

• Use the existing vent or obtain a new one
• Modify to attach barb and hose for attaching external vent
• Modify to use current Stihl vent part number 16 / 17

I guess if anything this posting will have a more complete information to help others down the road.

Patrick