Fuel expansion tank?

[joeseth]

Hi guys, does anyone know what the plastic bottle is up in the rear o/s wheel arch? I'm guessing its some sort of breather/overfill/expansion tank for the fuel tank? And more to the point do you need it haha

[Simon13]

yes leave it it there part of the breather system and weighs about half a kilo probably

[magpie]

what's in yours ^

[Simon13]

eh?

[magpie]

mines empty ....weight wise .

i'm sure we both have more pressing minorisms though to get along with like the nice box some £40 pin stripes turned up in .

Btw the box those parts arrived in i bought from you is well mullard ya robbing coont!


Tack tack

[joeseth]

Yeah weighs nothing, it's an empty plastic bottle ha. Though I didn't know if it was supposed to be empty as mine has fallen onto the wheel and rubbed a hole through it! I didn't even know it was there was well confussed! Should I get another? Or just leave the pipes bodged up as they are at the mo?

[age]

taken from a similar thread on e30owners.com


The tank does need to be vented as pressure can increase or decrease with temperature changes.

Have you seen what happens to a petrol can? They can swell with pressure or collapse with vacuum.

The chamber and piping allow for this so if you remove it you would need to use a valve to vent the tank. You could have a problem with fuel vapour or smells.

The original system overcomes these problems. Also if you modify the fuel system without declaring it your insurance would be invalid, not a problem if its a track car.

[Brianmoooore]

Bottle may be empty most of the time, but under certain circumstances, such as when parked in the hot sun or filling the tank with petrol, it may partly fill with petrol, so you can't get away with just leaving things as they are.
Neither can you seal everything off, or you'll find that your 55 or 62 litre tank has suddenly become about a 35 litre tank.

[joeseth]

Thanks, will try get a new bottle soon then or repair the old one. Luckily I didn't seal the pipes as I thought it mite create a vacuum and then not get any fuel coming through. They are cable tied up and the ends covered just enough to stop any dirt getting in, so hopefully will work as a temp fix. Damn winter, everything going wrong!

[Phill172]

Interesting read, mine fell out a while ago! Didnt think to much of it and threw it away

Oops!