Fuel System Breather Valve info
Posted
#717132
(In Topic #86547)
Local Hero
Fuel System Breather Valve info
1. Black cap glued to gray body - outlet goes down to the back of the tank to the trumpety thing
2. Cream cap with one way valve (lets air in only) and small hole in centre
3. Cream Valve seat
4. Valve carrier - with valve pin that seals the hole in the valve seat when it lifts
5. Ball weight
6. Valve body with outlet that goes to the tank
So, as far as I can see, there are three possible scenarios:
A - Tank heats up and air/vapour wants to get out
B - Tank cools/fuel used and air wants to get in
C - Tank causes fuel surge into breather
The top of the unit is the black end.
C is straight forward I think - The fuel surge will lift the valve body and close the valve ensuring that no actual fuel escapes
A - A slow release of air/vapour is possible past the gravity valve and through the single small hole in the cream cap
B - Fuel use and tank cooling will create a slight drop in pressure and would suck air in - this would come in via the one way valve in the cap which has 4 holes and through the unvalved hole
So either way the tank should pressure balance over a period of time. I always argue that the tank should wooosh (suck in air when opened) as this is what I've experienced with loads of cars.
I suspect that this is because the amount of fuel used is greater than the air drawn in due to the small holes.
This would mean that eventially you'd get fuel starvation due to the low pressure in the tank or the tank would collapse!!! Clearly this is wrong and the stripped valve would indicate that no wooshing should be heard.
Over to you lot…..
Posted
Local Hero
Posted
Old Timer
it caused a hell of alot of problems, i replaced with a second hand one, and its started doing it again….thing is, it can only get blocked up when dirty fuel goes up the breather pipe, and the valve doesnt work….dunno y really…inline filter did have a tiny bit of crap in it…which is enough to block something that small i suppose….
u mentioned a while back u had loads of breather valves, how much wud u want for one inc PandP
Thanks Josh
Posted
Member 125 - 2005
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Posted
Member 125 - 2005
Mk1 2l TSR G60. .getting. There twice as fast
Mk1 lhd diesel…….getting. There for half the cost
Mk1 lhd diesel…….getting. There for half the cost
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