Husqvarna 555 RXT Brushcutter - fuel cap is very very stiff to turn

[Muddy42]

I have owned this machine since new, about 3 years.  Its been great but the fuel cap has gradually got very tight.  If I only tighten it normally by hand, it then leaks petrol.  I need to use both gloved hands and apply some serious force (but it then still weeps fuel a bit). There is no obvious sign of cross-threading, missing washer or dirt in there. It almost looks like the plastic of the fuel tank (male) is too large for the cap. Its tight to turn from the start, and stays tight over several turns of the cap, if that makes sense.

 

It gets used so much in the summer that I use regular E5 ethanol fuel in it, but flush it out with a tank of aspen in the autumn.  I have heard reports that ethanol can make some plastics swell, but is this just another ethanol-old-wives tale?  But before I use sandpaper on it, I thought it best to ask if anyone else had found this to be a problem. I could also try adding an extra washer on account of the leaking. Thanks

[Stubby]

Get a new cap . 

[Muddy42]

30 minutes ago, Stubby said:

Get a new cap . 

I might, its just I'm not sure anything is wrong with the cap.  Looks fine.

[Stubby]

21 minutes ago, Muddy42 said:

I might, its just I'm not sure anything is wrong with the cap.  Looks fine.

They distort over time . Not always obvious until you get the symptoms you describe .  

[Muddy42]

12 minutes ago, Stubby said:

They distort over time . Not always obvious until you get the symptoms you describe .  

Ah OK, will try that.

[butters]

I used to have 3 of them and they all done this. 
 

Sometimes go so tight used to have to get mole grips to loosen them

[Muddy42]

2 hours ago, butters said:

I used to have 3 of them and they all done this. 
 

Sometimes go so tight used to have to get mole grips to loosen them

 

Thanks both.  I guess its good to know that its the cap that is at fault (and easily replaceable) rather than the whole blooming fuel tank.

[Muddy42]

 

@Stubby @butters So two months later and I bought a new fuel cap for my Husqvarna 555rxt as part of a job lot of filters etc for end of year servicing.  And the new fuel cap is ridiculously tight as well ! Its tight from the first turn onwards.

 

The fuel tank is totally empty and dry. Everything is clean  I was thinking of either:

- lots of measuring of the thread and compare it to the original spec (if I can find this);

- or covering the orange fuel tank threads in dark ink and then screwing in the fuel cap to find any high spots on the fuel tank threads which can be removed with sandpaper. After blocking the fuel tank with tissue paper to stop anything getting in.

 

Any other ideas?  Thanks

[GarethM]

Is it like the Stihl cap with an o ring?.

 

I bought a few spare o rings instead of the cap as it's usually the chip that damaged the seal, maybe go down a thickness or a softer NBR.

[Muddy42]