# Great News Regarding Too-Tight Gas Caps on Chainsaws



## DanCorcoran (Nov 29, 2011)

Or at least on my chainsaw.  I have an 18", 42-cc Craftsman chainsaw that's about 8 years old.  (Pause here for derogatory comments about Craftsman, Poulan, etc., chainsaws).  After the first year or so, it became increasingly difficult to remove and replace the gas cap.  I eventually resorted to using pliers.  Then I read on this website that some believed it might be due to the ethanol added to most gasoline and that "perhaps" letting the caps dry out for a while would shrink them to their original size.

Well, about a year ago I replaced the original gas cap with a new one.  Instead of discarding the old one, however, I set it on the shelf.  A few days ago, I took it out to try on the chainsaw (because the new one was getting difficult to use).  Lo and behold, the old one went on easy-squeezee, just like new!

Lesson learned: have two gas caps and alternate them.  (What I don't know is the minimum time it takes for one to dry out and shrink; mine sat for a year).


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## Jack Straw (Nov 29, 2011)

The information I get on this site is priceless. I never would have guessed that would happen. If some one I know has that problem I'll have the answer they will think that I am really smart.


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## Joey (Nov 29, 2011)

The seasoning time on gascaps all depends on the brand of saw being used.   I'm just sayin....... :coolgrin:


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## bpirger (Nov 30, 2011)

But my hard to turn cap is my oil cap, not my gas cap!  So what's up with that?


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## cygnus (Nov 30, 2011)

Oak caps take _forever_ to dry out.


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## bogydave (Nov 30, 2011)

bpirger said:
			
		

> But my hard to turn cap is my oil cap, not my gas cap!  So what's up with that?



You put it on to tight :lol: LOL
Have a small paint brush in the saw tool box, (or on a string attached to the jug) brush off the wood chips before you take the caps off to fill up.
Helps keep  any chips from falling in the tanks & keeps the threads clean.


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## BrotherBart (Nov 30, 2011)

Yep it is the ethanol. When these saws were made corn liquor was only moonshine. Not a gas additive. I have a second cap inbound that I bought on eBay yesterday so I can rotate putting my caps on the 405+ into rehab to dry out.


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## wkpoor (Nov 30, 2011)

I'll have to ad gas caps as another reason I burn Avgas in my saws. I've never experienced the stuck cap sindrome on my saws but I have on others.


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## BrotherBart (Nov 30, 2011)

I'll buy a cap every five years rather than run out to the airport to buy my gas. Of course you just bring it home from work with ya.  :cheese:


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## oldspark (Nov 30, 2011)

I sure am glad they dont make us buy that crap here.


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## BrotherBart (Nov 30, 2011)

oldspark said:
			
		

> I sure am glad they dont make us buy that crap here.



But that is where the damn corn comes from!!


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## oldspark (Nov 30, 2011)

BrotherBart said:
			
		

> oldspark said:
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Ironic aint it. :lol:


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## wkpoor (Nov 30, 2011)

BrotherBart said:
			
		

> I'll buy a cap every five years rather than run out to the airport to buy my gas. Of course you just bring it home from work with ya.  :cheese:


Well I wouldn'd either if that were the only benefit. I just addded that to my long list of reasons. One trip to the airport with a couple 5 gallon cans and most people would be good for a year or more. And since it keeps for who knows how long (I've got some over 3 yrs old) it might actually save a trip or 2 somewhere. But yes you are right it is very convienent for me. That and Jet A for the tractor.


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## mayhem (Nov 30, 2011)

DanCorcoran said:
			
		

> Or at least on my chainsaw.  I have an 18", 42-cc Craftsman chainsaw that's about 8 years old.  (Pause here for derogatory comments about Craftsman, Poulan, etc., chainsaws).  After the first year or so, it became increasingly difficult to remove and replace the gas cap.  I eventually resorted to using pliers.



Had that exact same saw for about 15 years of faithful service.  Also had the exact same issue with the gas cap, b&c oiler cap did the same thing so I'm pretty skeptical it has anything to do wiht ethanol.

For what its worth, the gas cap on that saw is specifically designed so that the shaft of the scrench can be inserted between the two lobes on the cap and you can turn it very easily with the extra 6" of leverage.  Pliers not required and you won't mess up the gas cap that way.


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## MasterMech (Nov 30, 2011)

Joey said:
			
		

> The seasoning time on gascaps all depends on the brand of saw being used.   I'm just sayin....... :coolgrin:





			
				cygnus said:
			
		

> Oak caps take _forever_ to dry out.



Hey do you guys stack your caps in single rows, top-covered or just throw 'em all in a corner pile like me?  %-P  :snake:


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## seeyal8r (Nov 30, 2011)

I have never burned anything other than Ethanol Free gas in my Stihl Chainsaws and I've never had a single problem with gas caps, fuel lines, or any other plastic or rubberized part becoming brittle, swelling, breaking, or clogging.


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## BrotherBart (Nov 30, 2011)

All I know is that this will be cap number three for the 405+ and the original 20 year old oil cap spins off without a problem. The first gas cap finally got so bad that it took channel locks to get it off and it ripped the threads off coming out.


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## DanCorcoran (Nov 30, 2011)

mayhem said:
			
		

> DanCorcoran said:
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I'm aware that the cap can be removed with the "scrench", but unfortunately it can't be installed that way, hence the pliers.  (But now I just use my fingers, because the new "old" cap fits just fine).


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## Adkjake (Nov 30, 2011)

Last summer I heard or read somewhere that if you put the plastic gas caps that had expanded due to ethanol, out in the sun for a day it will shrink them. Thought, sure urban myth, tried it. Damn if it didn't work.


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## mayhem (Dec 1, 2011)

DanCorcoran said:
			
		

> mayhem said:
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## MasterMech (Dec 1, 2011)

mayhem said:
			
		

> Wait, you have trouble putting your cap back on too?  I guess I missed that part...I've never experienced that with any of my saws.  They all are always on the ahrd side to remove the caps by hand but I have never had an issue screwing the cap back on.



The ethanol makes the cap swell and become physically too tight to screw into or out of the tank.  It's not merely a case of an overtightened or vacuum-locked cap.


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## DanCorcoran (Dec 1, 2011)

MasterMech: correct.


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## mayhem (Dec 1, 2011)

> The ethanol makes the cap swell and become physically too tight to screw into or out of the tank.  Itâ€™s not merely a case of an overtightened or vacuum-locked cap.



The cap itself swells up?  Not the seals but the actual plastic of the cap? 

Weird.  I can't get anything other than E10 here, been that way for almost as long as we've been unable to get leaded gas.  How come I've never run into this before?


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## daveswoodhauler (Dec 1, 2011)

Funny, I have the same exact saw as the OP, and run into the same issues with both the gas cap and the oil fill cap. Actually, the oil fill is the really bothersome one, but know I know what to use the scrench for


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## DanCorcoran (Dec 1, 2011)

Yes, my oil fill cap has the same problem.  I just haven't bothered buying a new one...I use pliers on it, too.


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## BrotherBart (Dec 1, 2011)

The word from on high, Stihl USA:

"Specifically, the levels of ethanol, aromatics or other additives in some gasoline sold in the United States may distort parts of the fuel cap, which could make caps more difficult to install and/or remove"

From Husqvarna customer service:

"Ethanol in the fuel has caused the fuel tank and gas cap to swell. "

Poulan says the same thing.


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## Adkjake (Dec 1, 2011)

Nice on their part. But how about a fix? Free replacement caps now that it is a known problem. Unlikely

How about make the new saws with aluminum or other metal sleeves and caps? Might cut in to the profit margin
by 50 cents.

Rant over


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## BrotherBart (Dec 2, 2011)

Adkjake said:
			
		

> Nice on their part. But how about a fix? Free replacement caps now that it is a known problem. Unlikely
> 
> How about make the new saws with aluminum or other metal sleeves and caps? Might cut in to the profit margin
> by 50 cents.
> ...



Actually Sthil is replacing a bunch of'em free of charge. The words came from the recall notice on their website.


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## Adkjake (Dec 2, 2011)

Oh sure, I bought a H'varna


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## mayhem (Dec 2, 2011)

It just doesn't make any sense at all.  Ethanol has been in gasoline in widespread use for 30 years now.  The fuel tanks don't seem to have a problem swelling up on the saws, so why the ehck are they still making fuel caps out of what is obviously the wrong freaking plastic?  All its doing is frustrating their customers and costing the saw manufacturers lost revenue is free replacement caps.  I know the fuel cap in my truck is made of plastic and has a gasket, but it doesn't sweel up or anything and its got exposure to E10 24x7, though I guess it never sees liquid exposure, just fumes.

If the oil caps are having the same issues, doesn't that sort of absolve ethanol as the problem here?   Same problem but zero ethanol exposure suggests to me that its got to be something else.  Or is there 10% ethanol in bar oil too?


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## Corey (Dec 2, 2011)

I'm with you, mayhem - I always have 10% ethanol (or more) in my gas - never once have had trouble with a cap... never had trouble getting the cap off a bottle of vodka, whiskey, or any other spirit either...and those are way more than 10% ethanol!!  The cheap stuff even comes in plastic bottles which seem to hold up fine as well.

My oil cap is the one which always gets stuck, so if anything I'd say it is the gunky hydrocarbon dinosaur oil part of the equation which is messing up the caps.

To take the original 'study' at face value is like saying you eat 9 bowls of ice cream (90% gasoline) and one bowl of salad (10% ethanol) ever day - and your waistline expands.  So you quit eating food for several days and your waistline shrinks...therefore it must be the salad making you fat.


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## oldspark (Dec 2, 2011)

You guys are funny, there is a problem with the E gas in some cases, have you seen the problems with the plastic gas tanks on Ducati and some other motor cycles, I believe there was a lawsuit. Why they dont change the plastic is a good question, not sure how old the lawsuit is either.


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## oldspark (Dec 2, 2011)

Oh yea I forgot to mention what the problem was with the Ducati tanks, drum roll-it was expanding.


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## DanCorcoran (Dec 2, 2011)

"If the oil caps are having the same issues, doesnâ€™t that sort of absolve ethanol as the problem here?  Same problem but zero ethanol exposure suggests to me that its got to be something else.  Or is there 10% ethanol in bar oil too?"

What do you mean "bar oil"?  I've been putting 87 octane unleaded in the reserve tank, too, so both caps are exposed to ethanol.


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## 'bert (Dec 2, 2011)

DanCorcoran said:
			
		

> "If the oil caps are having the same issues, doesnâ€™t that sort of absolve ethanol as the problem here?  Same problem but zero ethanol exposure suggests to me that its got to be something else.  Or is there 10% ethanol in bar oil too?"
> 
> What do you mean "bar oil"?  I've been putting 87 octane unleaded in the reserve tank, too, so both caps are exposed to ethanol.



"Reserve Tank"  Thanks just spit beer all over my keyboard!   :lol:


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## Corey (Dec 3, 2011)

There may be problems with the plastic, but it seems quite a stretch to blame ethanol when plenty of cheap plastics hold high concentrations of ethanol with absolutely zero problems.  There must be a million liters of vodka setting in plastic bottles right now with no swelling.

This will likely fall on deaf ears, but I would suggest if the issue is related to the gas and not the plastic, the most likely scenario is:

In the 'old days' 87 octane gas was probably more like 88 or 89 because the '87 octane' rating is actually a minimum specification. Plus it contained many big, chunky molecules (technical term) which aren't terribly reactive with plastics/polymers.  In the drive for more profit, the refineries learned to better control the product, so 87 octane is really 87 octane, or even 86.55 octane which would round up to 87.  In doing this, they crack all the nice heavy molecules into lighter ones which take up more space.  Since we buy gas by the volume (gallon), less gas taking up more space is a cheaper product (just like making a cord of tree leaves would generally be easier/cheaper than making a cord of oak wood.

The down side - all small/light molecules are in a range which are reactive with plastics.  When ethanol comes along at 107 octane, it allows the refiners to make even crappier gasoline...83, 84, 85 octane...then blend in ethanol's good properties and still have a product which meets the minimum specs.

If ethanol is to 'blame' it's only because the very high octane properties have allowed refiners to make extra crappy gasoline which has the potential to me much more reactive with plastics, but still meet octane spec.


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## oldspark (Dec 3, 2011)

There is enough info out there to convince me there is a problem with the E gas but like you said it is the plastic, they are seeing it in europe now (gas tank problem) with the 5% E gas.


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