Removing roll-over tanks.

Post by **Brooky** » 21 Jun 2007, 11:15

I want to get rid of those wretched fuel breather tanks located high up in the rear of the front wheelarches.
My understanding of their purpose is that they have a ball valve in the top and are designed so that if the van rolls over, the ball valve falls shut & prevents fuel spillage.
When upright (hopefully all the time) the tanks simply act as a supplementary breather system. They don't appear to be necessary for this purpose as there is a big bore breather pipe that feeds back into the filler neck & presumably breathes via the vented fuel cap.
I want to get rid of the tanks because they are so positioned as to create inaccessible dirt traps both above & behind them.
Each tank has two small bore pipes that feed into them from the top of the main fuel tank. I'm proposing to simply connect the two feed pipes together with a loop of fuel hose.
Can anybody see a problem with this,
assuming that I keep the van upright at all times!
Brooky.

Post by **R0B** » 21 Jun 2007, 15:53

i would be leaving them where they are if i was you.im sure they are not for just in case you roll the van over...if mr vw saw fit to put them there.then there they should stay.imo

Post by **Ivor Brownun** » 21 Jun 2007, 17:09

good advice from Rob, if vw could have saved a quid by not fitting them they wouldn't have,

Post by **Mocki** » 21 Jun 2007, 18:42

you will find that the shape of the tank means there would be a massive air pocket at the top of the tank either side and you would never get above 1/3 full because the air would stop the petrol going in . . . thats why mr vw fitted them

Post by **Plasticman** » 21 Jun 2007, 19:23

As M says, leave them their volume and plumbing is configured specifically to enable an afterthought of a tank to be filled.
Mike

Post by **Hacksawbob** » 21 Jun 2007, 19:32

the y are there for the fumes to collect and drip back down also allows balancing out between one side of tank and the other as there is a big dip in the middle, Your insurance company may have a case not to pay out in the event of an accident.

Post by **Rozzo** » 21 Jun 2007, 21:03

we've had this topic before and i'm getting rid of mine. loomin rot trps is all they are.

Post by **trundletruc** » 22 Jun 2007, 09:28

I would not remove mine as they are needed when you fill up to the bottom of the fuel filler on a cold day and the day warms up, the petrol expands and flows up into the tanks. They also release the air from the top of the two bumps in the shape of the tank and allow you to fill up properly.

On my 1984 van there is a breather pipe from the top of each tank which goes open ended into the cross chassis frame. There is no valve in case you turn over! I know from looking in the Bentley manual that later vans had these two pipes going to a carbon filter so as not to polute the air.

There is only one nut to get the tanks out (tank will come out easier if you elongate the hole in the tank tab for next time) and then you can clean behind them.

VW knew what they are doing.

Post by **brookie** » 22 Jun 2007, 10:35

They're not roll-over tanks, just expansion tanks Brooky, to allow cold fuel (when you've brimmed it) to expand if it warms up. The top hose is simply a vent to atmosphere to allow for this expansion (and contraction if it cools) and also allows air to vacate the main tank as you fill up.
To remove or not to remove that is the question.....

After careful consideration I got rid of mine for the same reasons as you. I have had no problem with fuel leaks or topping-up to full. The only thing I would not do is fill up to max in the cool morning in South of France and then not drive as you might get fuel venting as it expands. This is not a prob for me as when I brim it I tend to drive it and the expansion can't keep up with the fuel being used by the engine!
I connected the two lower vent hoses to a Y connector then fitted a new vent hose to the remaining connection of the Y and routed that high in the wheel-arch and back down to the inner arch where the original vent line went.
Like I said, have had no probs with anything, try it and see, you can always put it back to original spec if you want.
Horses for courses, I'm not saying one way is the best, just it's perfectly feasible to do it without breather tanks without problems.

Post by **Brooky** » 22 Jun 2007, 11:34

Well thanks everybody. At least I now know why they are there. I must admit however, that just like my namesake brookie, I rarely brim the van & then don't drive it immediately and as such the expansion shouldn't be a problem.
As for being able to brim it in the first place, because of the dip in the middle, I would need to know where the big breather (the one that feeds into the filler neck) enters the top of the tank. I'd be grateful if somebody could tell me that.
Brooky.

Post by **trundletruc** » 22 Jun 2007, 11:54

it enters the thighest point of the tank on the right side but has no connection with the highest point on the left side. One of the little pipes connects these highest points.

Hope this helps

Post by **Brooky** » 22 Jun 2007, 12:17

It certainly does trundletruc. Thanks.
So, If I do what I'm proposing to do, I will lose the capacity of the raised section of the tank on the left hand (kerb) side, but as soon as I move off, normal sloshing will level out the fuel leaving me with slightly (how much?) less than a full tank but allowing expansion & breathing via the big breather.
Does that sound reasonable?
Brooky.
Must also remember to keep the van upright!

Post by **brookie** » 22 Jun 2007, 12:30

No. the left hand side will be full of fuel too as the two hoses you've joined together on that side to the Y piece will allow any trapped air to vent when you fill up.

Post by **trundletruc** » 22 Jun 2007, 13:24

The "big" breather that goes to the fuel filler will not breathe once the fuel filler has been put on, so don't rely on this to let air into the tank as the fuel is used up.

The fuel filler cap should be sealed otherwise on a long left hand bend, or parked on the kerb the fuel will slosh out. Particularly worying if you have a gas fridge vent close by!!

Post by **T3teedub** » 25 Jun 2007, 12:37

sukhoi27 wrote:i would be leaving them where they are if i was you.im sure they are not for just in case you roll the van over...if mr vw saw fit to put them there.then there they should stay.imo

Is this the same Mr VW who saw fit to put 1600 Aircooled engines in the early T25s then had to replace many of them within the first year?

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