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defender extended fuel breather system


JST
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As some have noticed and pointed out to me on various occasions my fuel filler cap leaks. This only occurs when off roading but its enough to annoy and the amount of fuel leaking is bad for my wallet and the environment (although if its leaking I cant burn it, not sure which is worse for the environment – anyway)

Having taken apart the std venting fuel cap it was apparent that the plastic ball was jammed in position and therefore didn’t rise with the fuel level to activate the rocker to block off the vent – hence it leaked. Fixable but still annoying that it broke in the first place (only 9mths old) plus I still didn’t really have a good feeling that it would work properly or that water wouldn’t find its way into the fuel system.

So firstly I ordered a replacement non-venting lockable fuel cap (less than £15 Bearmach) RTC4741. Then I purchased some 13mm pipe and a ‘T’ piece in order to extend the existing breather. 13mm because that’s the size of my existing closed system breather pipe.

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The T piece is inserted into the closed system pipe

TpieceSmall.jpg

the new 13mm hose is then connected passed through a hole in the wheel arch part of the loadbay to exit just behind the bulkhead. Currently it has a U bend in it and whilst I appreciate the bore is large for a breather this is due to firstly it matches the bore of the existing closed venting system, and I have a 13mm one way valve coming to go on the end of it. The alternative would be to fit a reducer and run smaller bore piping up which would do the job without sticking out so much!

UbendSmall.jpg

13mm pipe was £4.95 the T piece £2.45, it even came with the jubilee clips. So about £23 all up.

Now I dare say someone will come along and point out a fundamental error with doing it this way so if there is one grateful if it could be pointed out please.

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James, I think you'll also find fuel comes out of the breather when filling up / moving with a full tank (pockets of air and fuel in the pipe seem to get pushed with a fair bit of force when the fuel in the ank moves). Plus, the diameter is quite big so I can see insects crawling up there getting into the tank. Also, why not go to the top of the vehicle? That's without thinking about rollovers when fuel is going to tiddle out very fast.

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Mo it is the original part of the closed system venting, one part goes to the top of the tank, the other to the top of the filler.

In short no i dont think you do need it, but this way, at least some of the fuel sloshing around will go to the filler and straight back into the tank rather than all of it up the extended breather. it was also easier to put in a T peice and cut the pipe than just disconnetc the old pipe extend that and then (the hard bit - block off the bit into the top of the filler)

Will good point on insects etc, alot of rabbits around here at the moment as well, i will have to be careful!!! - i think i will put a reducer in the end of the pipe unitl i get the one way valve. at least minimise the entry/exit hole.

I am hoping the pipe is long enough to stop an sloshing fuel that is moving around coming out the end of it.

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James,

If you put an inline filter on it (which would fit that bore of pipe), that would:

  1. Stop bugs and creepy crawlies (and rabbits :ph34r: !!) crawling down the pipe.
  2. Maybe act as a bubble breaker to stop fuel slugs climbing the pipe and sloshing out of the top....

:D

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James, If you've got a valve fitted then all thr points (bar the height of the breather) aren't an issue.

Mo, I think a T peice is a good idea as, otherwise, you won't be able to completely fill the tank as air will get trapped in the area above the top of the filler neck as the air in there can't be escape (due to the one way valve) and be displaced by fuel.

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Personally Im concerned about innocent children being caught in the pipework

yet another example of a 4x4 gas guzzler showing no regard for children or fluffy animals getting injured

only issue I can see with it it the use of non-fuel grade hosing - just in case you get a REALLY fussy MOT chap?

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Donald - thats a good idea and i will take it up IF my one way valve is a no show!

Will - still waiting for the valve so your points are valid at the moment. why to the top of the vehicle though?

Just been for a test drive, filled it with a jerry can top to the top, parked on a side slope - no leaks - excellent (suspension dislocated on the up hill side (not alot though) so i reckon it was enough of lean!)

MOT..... err just had one so wont worry about that for another year, dont think he would mind though.

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Will - still waiting for the valve so your points are valid at the moment. why to the top of the vehicle though?

Part of the reason I'm doing this is to be waterproof even during deep wading. Once the breather is underwater it'll start to pull in water instead of air which is why I'd err on the side of caution and go to the top of the vehicle.

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Chris - if you get a picky one then in theory all parts of the fuel system have to be rated

Will - you planning on going into deep water then?

with all these gas guzzling 4x4s about the global warming will raise the sealevel so far he'll be in deep water before its finished & trying to drive out the garage! :D

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Will, if you have a breather to the op of your wagon thats bloody deep water, especially as if yours is stuck in water its prob on a trailer as well - so thats deep!

Yeah, I know it'd be deep but if you're going to put one breather up to roof height why not put them all?

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