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Pressure release filler cap?
speedyxjs - 30/9/09 at 03:10 PM

I was playing with the cooling system yesterday and got thinking, can you get a pressure release filler cap for the fuel tank like you do with the coolant resevior?
This would save me needing to play with extra fuel lines

Staple balls - 30/9/09 at 03:15 PM

Aren't most caps vented anyway?

adithorp - 30/9/09 at 03:20 PM

Why would you want your fuel tank to be pressurised?

speedyxjs - 30/9/09 at 03:29 PM

quote:
Originally posted by adithorp
Why would you want your fuel tank to be pressurised?


You dont. Thats why you need a way for the vapours to get out/air to get back in.

l0rd - 30/9/09 at 03:31 PM

Isn't this why you have those one way valves?

blakep82 - 30/9/09 at 03:51 PM

quote:
Originally posted by l0rd
Isn't this why you have those one way valves?


yeah, but i see what he's saying, it would be nice if that was built into the cap, rather than having seperate tank connections, valves and pipes

speedyxjs - 30/9/09 at 03:56 PM

Just found this that says it is vented. Any good?

adithorp - 30/9/09 at 04:06 PM

quote:
Originally posted by speedyxjs
quote:
Originally posted by adithorp
Why would you want your fuel tank to be pressurised?


You dont. Thats why you need a way for the vapours to get out/air to get back in.


But you were comparing it to a radiator presure cap, that holds presure up to a set level (say 15psi) and then releases anything over that giving a presurised system.
With a fuel tank you want a vented system, so you need either a vented cap (prone to leaking) or a breather system.

speedyxjs - 30/9/09 at 04:08 PM

quote:
Originally posted by adithorp
quote:
Originally posted by speedyxjs
quote:
Originally posted by adithorp
Why would you want your fuel tank to be pressurised?


You dont. Thats why you need a way for the vapours to get out/air to get back in.


But you were comparing it to a radiator presure cap, that holds presure up to a set level (say 15psi) and then releases anything over that giving a presurised system.
With a fuel tank you want a vented system, so you need either a vented cap (prone to leaking) or a breather system.


How could a vented cap leak?

adithorp - 30/9/09 at 06:34 PM

Vented caps basically just have a small hole to let gas in/out; no valve.

Fill the tank close to the top on a hot day. Fuel comes out of the underground tank at 15'c and then warms up and expands and out it'll come. Or just corner hard with a full tank and a filler thats not far above the tank and you'll find out why early Metro's were recalled for new caps after the Police crashed a few (fuel leaked onto the o/s rear wheel). Whereas with a breather with 2 way valve it'll seal.

speedyxjs - 30/9/09 at 06:59 PM

^^^ Thanks