New O-Rings for Flippy Caps

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TheTone
Joined
Jan 31, 2017
Messages
886
Location
North Central Arkansas
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:
20191005_181100.jpg 20191005_181224.jpg
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.
20191005_181405.jpg
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.
 
Patrick62

Patrick62

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Joined
Jun 13, 2005
Messages
2,298
Location
Colorado
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 !
 
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Reactions: svk
Joined
Oct 19, 2009
Messages
27,256
Location
MN
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.
 

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