New O-Rings for Flippy Caps

[TheTone]

I was getting ready to start a rebuilt saw, so I poured in a little mix, put the old flippy cap on and turned the saw right side up. There was a dribble of mix coming out of the bottom of the cap. I took off the O-ring and slipped on a new one that I had bought on Ebay and no leak. Here's what they looked like side-by-side:

The readings on the calipers are where the rings fell off. Four mm difference in inner diameter. The old ring was 3.3mm thick, the new one 3.5mm.
The old ring also had grooves worn into it.

The lot of 50 Buna rubber O-rings of the specified size for Stihl fuel caps (3.5mm x 25mm I.D.) came to $0.21 each, shipped. Worth a try for those leaky flippy caps that look OK otherwise. Might want to carry a few with you into the woods.

 

[user 122190]

So what you are saying is that O'Rings don't last forever?

I have found that soaking the entire flippy-cap in a solvent goes a long ways in keeping them working properly.

 

[TheTone]

So what you are saying is that O'Rings don't last forever?

Yes. That's why I put in a new one.

 

[Cycledude]

Glad you got it fixed, Flippy caps are mostly just an extra place for trouble ! Stihl loves selling them. As far as I know there is no other chainsaw manufacturer using such a foolishly complicated gas cap.

 

[user 122190]

.... foolishly complicated gas cap.

Really?

 

[svk]

My friend’s 211 had the same thing, the o-ring on the oil cap was all cracked up. I bought two sizes and the smaller one worked great.

 

[Patrick62]

perhaps the fuel degrades the O rings some?
However, I have seen just as many leaks on the bar oil cap....

Keep them clean. I really have not had many troubles, but you are on something.. I should stock the O rings !

 

[svk]

perhaps the fuel degrades the O rings some?
However, I have seen just as many leaks on the bar oil cap....

Keep them clean. I really have not had many troubles, but you are on something.. I should stock the O rings !

I was quite surprised that my friend's oil o-ring went first. To my knowledge the original fuel ring is still in there 2.5 years later.