[Steven Biggs]

Has anyone ever sealed up there tank lid making it 100% watertight . Or any one any ideas how to do it . Reason is ive emptied it ready for installing in my new van tomorrow. And just flipped it over giving more room in the van . The lid is no longer on top of the tank . But is now on the side but at the top . So I can get about 500 litres in no problem . But just when I need to fill to the top , it's 650 litres . Cheers anyone .

[richard groves]

Hmmmm, good luck with that 
I've never known anyone do that.
I suppose like you say, its still at the top but on side, something may work.
You can buy stixall ( think that's how its spelt ) in tool station . you apply it with a sealant gun so you could try coating the thread of the cap with it also before you screw it on. Its a glue as well as a waterproof sealant even sets under water so maybe worth a try 

[Shrek]

I wouldn’t advise it as sometimes you get debris in your tank and it needs hoovering out

[Steven Biggs]

I've never emptied or hoovered it out in 9 years . Even when I changed vans 7 years back I drained it to about 50 litres and 3 of us slid it straight in the new van . 

[Plankton]

9 year old, punt it and buy a new one instead of water leaking in the new van!

[Steven Biggs]

Yeh I could do that . But I'm still undecided which way to go . Rash over at the shop I use in Leeds offered to part ex it for me on a new upright one  but another thing to consider is which is the safest in the event of a crash . ? An upright 650 or a flat 650

[Don Kee]

You dont want it water tight. You'll just create a vacuum when you keep using water and not replacing the space with air.

[Steven Biggs]

I would make a small hole in the top to fit a hose in to fill it .. so I would just need to seal the lid .

[richard groves]

I'd use geka fittings and a blanking cap with a small hole beside it with a foot of microbore or pole hose in it as a breather.

[nathankaye]

I would assume that people read before they reply, some comments are totally patronizing. He's asked about sealing the lid and not told how hes going to fill the tank nor about air holes etc.  I thought people might conclude that he has that covered.
I would have thought that if you glue it as recommended and then perhaps for added measure use a ratchet strap for security when its under pressure.  Just open all your van doors and keep your equipment out the first time you do, for the just in case trial factor

[richard groves]

Not patronizing at all Nathan,  If Stephen drills a hole in top of tank to fill without any sort of fitting or cap then when tanks full and he's on a hill its going to slosh and spill out of it. I only give worthy suggestions or advice on here to help people. didn't you actually take my advice and buy some geka fittings yourself ?

[Stoots]

If its a 650 tank and you can get 500l in before the lid opening then i would thought the lid would be under very little pressure.

I would try something like a gasket sealant on the threads, screw it on and see what happens.

Do it out of the van with tap water  to see if it seals, the lid blowing off wont be an issue i dont think so just a case of getting it to seal

[nathankaye]

Not patronizing at all Nathan,  If Stephen drills a hole in top of tank to fill without any sort of fitting or cap then when tanks full and he's on a hill its going to slosh and spill out of it. I only give worthy suggestions or advice on here to help people. didn't you actually take my advice and buy some geka fittings yourself ?

I think my phone is on delay as ive probably read the same comments twice over and so my apologies.
As i thought a number had made comments on the vacuum factor which was initially irrelevant as Steve didnt ask about that side of his problem. But i also would take it that he aint stupid enough just to cut a filling hole at the top of the tank for filling purposes and not secure it with some type of fitting.
Therefore my comment wasnt aimed at you barry, sorry if it came across that way. As yes, i wasnt aware of the geka fittings untill you mentioned them and perhaps they may be of use to Stephen as well

[nathankaye]

If its a 650 tank and you can get 500l in before the lid opening then i would thought the lid would be under very little pressure.

I would try something like a gasket sealant on the threads, screw it on and see what happens.

Do it out of the van with tap water  to see if it seals, the lid blowing off wont be an issue i dont think so just a case of getting it to seal

I mentioned about  the pressure because he did mentioned there might be times when he fills the tank more than 500 and i assumed that meant a full tank