Drilling a hole in a plastic fuel tank: any problems I should know about first?

[David2452]

I notice that the installation instructions for my Webasto specifically said not to install their dip tubes into plastic tanks.

Indeed, and for very good reasons, the standard method doesn't work on plasic tanks, many AWB builders use plastic tanks and fit heaters with dip tubes, they all end up leaking,

 

[Daydream believer]

For those with CAV type filters
I could not stop mine leaking for several years i really struggled. I was even referred to as a spanner monkey by forumites on this forum
That hurt, as I was probably stripping diesels before they were borne
One day a relation of mine who works on farms so always messing with tractors-suggested i check that the filter was a genuine CAV
He hit the nail on the head - It was a clone
I bought a new one (now Delphi)
No leaks whatsoever & i do not have to over tighten the bolt as it seals easily
Infact I am told that if one over does the spanner bit it squeezes out the seal & then causes a leak

 

[VicS]

It's not so much the gasket, though that is inmportant, actually removing the flex from the tank is almost impossible with small fittings, unless you have access to the inside to fit a substantial flange along with one on the outside you are on to a loser.

With the tank in question it should be possible to gain adequate access to fit a good size flange ... I think.

 

[chal]

Thank you very much to everyone for the info and advice. I think I will have one last go with the syphon arrangement, using one of the less leaky filters and maybe a metal syphon tube (tightening the clamp on the fuel line to the tank take-off doesn't do much besides start to distort the plastic fitting) and if that still fails, I'll go down the flange route for the tank.

Cheers!

 

[chal]

One final thing: does anyone know if it's possible to buy an off-the-peg replacement metal dip tube anywhere in UK? A google search tends to bring up only USA sites (and even then mostly people welding their own). Possibly also a fuel tap that would not leak.