[nathankaye]

i used to put a microfibre cloth over the hole and then put the lid on.  worked well

[Spruce]

I had a leaky tank lid until i smeared a thin bead of vasiline on the o ring. 

It's just replicating what every mechanic does when he replaces a spin on oil filter when servicing your car. He smears the oil seal gasket with oil.

[Spruce]

I had this same problem so in the end I just changed the tank completely no matter what I did it leaked non stop I tried sealing it changing the lids etc still leaked,if you get a hole saw you can cut over the holes that are already there and then replaced with Grippa tank lids it will solve the problem they are 99% leak free but it’ll cost 160-200 quid to fix it.  My new tank had a tiny lid just big enough for the hose nozzle to go in and eventually it snapped off,I just drilled a hole over the top of it and fitted a Grippa lid,should have done it ages before although the other little lid didn’t leak it started to split but this was after years.

https://www.fisheriessupply.com/armstrong-nautical-round-watertight-compression-deck-plates

You're welcome, no need to spend that much.  GrippaMax was originally designed by Alex Gardiner, and it wasn't called GrippaMax, can't remember what it was called actually.  As far as I remember he was the one that originally used the Armstrong lids as they are perfect in sealing the tank. Just be mindful, they are designed to be used as watertight seals on boat compartments. Hence, your tank will pull vacuum. I'm not sure what venting Grippatank use now but I've got some fun pictures of my very early GrippaMax where the whole tank is imploded after my first job. Fitted a motorsport fuel tank spring loaded ball valve which works both ways, prevents spilling but can still let air in.

It looks as though they still use the same supplier.
https://www.grippatank.co.uk/6-vented-deck-plate

[NWH]

I had a leaky tank lid until i smeared a thin bead of vasiline on the o ring. 

It's just replicating what every mechanic does when he replaces a spin on oil filter when servicing your car. He smears the oil seal gasket with oil.

You can’t beat a bit of Lube round you’re O ring

[[GQC] Tim]

I had this same problem so in the end I just changed the tank completely no matter what I did it leaked non stop I tried sealing it changing the lids etc still leaked,if you get a hole saw you can cut over the holes that are already there and then replaced with Grippa tank lids it will solve the problem they are 99% leak free but it’ll cost 160-200 quid to fix it.  My new tank had a tiny lid just big enough for the hose nozzle to go in and eventually it snapped off,I just drilled a hole over the top of it and fitted a Grippa lid,should have done it ages before although the other little lid didn’t leak it started to split but this was after years.

https://www.fisheriessupply.com/armstrong-nautical-round-watertight-compression-deck-plates

You're welcome, no need to spend that much.  GrippaMax was originally designed by Alex Gardiner, and it wasn't called GrippaMax, can't remember what it was called actually.  As far as I remember he was the one that originally used the Armstrong lids as they are perfect in sealing the tank. Just be mindful, they are designed to be used as watertight seals on boat compartments. Hence, your tank will pull vacuum. I'm not sure what venting Grippatank use now but I've got some fun pictures of my very early GrippaMax where the whole tank is imploded after my first job. Fitted a motorsport fuel tank spring loaded ball valve which works both ways, prevents spilling but can still let air in.

It looks as though they still use the same supplier.
https://www.grippatank.co.uk/6-vented-deck-plate

Cool, I didn't realise they sold these seperately. This is cheaper then buying it from the states.

NWH, why did you say it cost £160-200?

[NWH]

When I purchased a lid from Grippa I’m sure they charged me around £80-90 for 1,when I rang up and ordered it Peter said to me are you ready for this the price is X and I’m sure it was about that figure.