Need help with locked aluminium fuel cap

Hi guys, 
 
I've got a bit of a dilemma on my hands. I am trying to get an aluminium fuel cap off a welded aluminium fuel tank inside my boat. The cap is so tight that you cannot loosen it with a pipe wrench... I think it might have loctite on the thread. I wouldn't like to cut it or heat it for obvious reasons. The cap is roughly 2" in diameter and on an angle. Any input would be appreciated. 
 
Best Regards, 
Brad.


Posts: 563

Date Joined: 27/08/09

Pour boiling water over it

Sun, 2013-09-22 20:03

Pour boiling water over it and the give it a try again, or an electric hot air gun, but only if you have no fuel or vapour leaks.

Posts: 25

Date Joined: 22/09/13

 Do you reckon boiling water

Sun, 2013-09-22 20:13

 Do you reckon boiling water is hot enough to loosen the bond? I'm not too sure about vapour leaks but the boat hasn't been used in over 6 years. Cheers. 

Posts: 563

Date Joined: 27/08/09

Maybe!!! At least with

Sun, 2013-09-22 23:44

Maybe!!! At least with boiling water you are not going to create an ignition source.

carnarvonite's picture

Posts: 8687

Date Joined: 24/07/07

Fumes

Sun, 2013-09-22 20:42

You can guarantee there will be fumes still in the tank even after all that time so don't go anywhere near it with anything that may create a spark.

If its accessible get a hammer and a dolly / gimpy on the other side of the cap and work your way round it hitting it every 1/2 inch or so to expand it enough to break the seal.

Posts: 25

Date Joined: 22/09/13

Yeah, I'll use a dolly if

Sun, 2013-09-22 21:33

Yeah, I'll use a dolly if there are no other ways to remove it without damaging the cap. Do you know if I would be able to get a replacement cap without paying for it to be specially machined? Cheers. 

carnarvonite's picture

Posts: 8687

Date Joined: 24/07/07

Loosened

Sun, 2013-09-22 21:56

Once its loosened you should be able to still use the same cap. There will be a seal that sits right down in the bottom of it and all you are doing is expanding it a few mm at most.

It will be a standard thread so getting a replacement won't be a hassle.

Gently, gently does it.

Posts: 25

Date Joined: 22/09/13

 Thank you. I'll try that

Sun, 2013-09-22 22:04

 Thank you. I'll try that tomorrow and post my results. Also, what would be the best way to remove the old fuel out of the tank? Should I try and siphon it or run it and replace the old fuel filter?

Posts: 5981

Date Joined: 17/06/10

Replace filter

Sun, 2013-09-22 22:14

I would recommend that you replace the fuel filter and remove the old fuel from the tank, not by running it through the motor though.
A good idea would be to flush the fuel tank and all the fuel lines as well if they have not had any use for a good number of years.