Draining Petrol Tank

[iandromiskin]

No doubt asked before, but what is the safe and correct way to drain the fuel tank of petrol before doing any work underneath the car (grinding, welding etc) ? I know to undo the bolt in the underneath of the petrol tank, open the fuel cap and let the fluid drain for a while into a bucket or whatever (and to dispose of safely), but is this enough to prevent vapour developing long term ??

[simmitc]

Absolutely not safe to work on an empty used tank, the vapour will linger for ages. A full tank is safer as there is no space for vapour. However, it depends on what work is being done and where. For general welding on sills, chassis legs, etc, the tank is fine as it is (as long as there is no leak). If you are welding close to the tank then the only sensible thing is to remove it - it makes access a lot easier too

[mogbob]

Disconnect battery before starting, fire extingisher at the ready.If you really must do it in the garage all doors windows open.A boiler or freezer in the garage might possibily create a spark on ignition enough to ignite the petrol vapour.Outdoors is best.
Block the holes whilst you store the empty tank..again outside is best.Plug the fuel line....an old plastic golf tee, plastic bag and tape up.
Bob

[bmcecosse]

Take great care with the drain plug - it may shear off. Safest thing is to fill the tank with water - right to the brim, if not removing it.

[laneychief]

Hi gents could anyone tell me the size of the drain plug?

Also the gearbox drain if you know that too.....

Many thanks!