Leaking Wema Flange/gasket

[xpertski]

Hi all,

Hope I can borrow some wisdom here please.

I have fitted a Wema flange and Viton gasket for a new sender, all fitted including using Loctite on the screws to ensure permanent and watertight screw fit, the Viton gasket is supposed to be sufficient around the base of the fitting but as you can see from the photos, when testing with some clean water it seems to seep a small amount of water through. Removing it isn’t an option and will unlikely make it watertight - I was thinking of sealant it epoxy around the outside of the fitting where the Viton gasket meets the tank - Epoxy or sikaflex?

I’ve also read online some people trying to bond with polyethylene try heat bonding using the tip of a soldering iron ...

Any suggestions or anyone tried to use something as a sealant on polyethylene that worked well?

Thanks!

[Pikey Dave]

This is used on polyethylene oil tanks. I’ve never had it fail yet.

[GuyC]

My first port of call would be to get a softer gasket. Is it though bolted or screwed? If it is the latter you might not be getting sufficient pressure to squash the gasket.

You could try making the gasket as small as possible to increase the pressure and therefore the squashing but it seems a bit counter intuitive and possibly not wise.

You could try asking Portmere Rubber or Bridge Rubber both in Southampton. Alternatively you could ask Tek Tanks to see if they have a recommendation.

I wouldn't attack it with a soldering iron until you have exhausted other avenues.

Edit - or just use what Dave has suggested.

[GuyC]

I've just Googled Heldite and whilst it is OK for petrol, it suggests it isn't compatible with ethanol. I don't know whether the ethanol in fuel would cause an issue or not.

[Pikey Dave]

Originally Posted by GuyC

I've just Googled Heldite and whilst it is OK for petrol, it suggests it isn't compatible with ethanol. I don't know whether the ethanol in fuel would cause an issue or not.

Ethanol in fuel hasn’t been an issue so far. I’ve used it on fuel (petrol) fittings & it’s been fine.

[xpertski]

Originally Posted by Pikey Dave

Attachment 135628
This is used on polyethylene oil tanks. I’ve never had it fail yet.

Thanks PD in your use have you just used it on the outside seam of what you have sealed -ie not between the gasket and the tank?

[Pikey Dave]

Originally Posted by xpertski

Thanks PD in your use have you just used it on the outside seam of what you have sealed -ie not between the gasket and the tank?

Use it on both sides of the gasket

[xpertski]

Originally Posted by Pikey Dave

Use it on both sides of the gasket

Ordered [emoji106] I took the flange and gasket back off so will use this as well. Thanks for your help guys!

[Pikey Dave]

Originally Posted by xpertski

Ordered [emoji106] I took the flange and gasket back off so will use this as well. Thanks for your help guys!

Get some methylated spirit too. It’s the only stuff that cleans it (Heldite) off, otherwise it gets everywhere.

[xpertski]

Originally Posted by Pikey Dave

Get some methylated spirit too. It’s the only stuff that cleans it (Heldite) off, otherwise it gets everywhere.

They have that at local Screwfix, cheap enough - will grab some of that

[Nos4r2]

Try these guys for different hardness viton sheet to make a new gasket with.

https://tym.co.uk

[xpertski]

Originally Posted by Nos4r2

Try these guys for different hardness viton sheet to make a new gasket with.

https://tym.co.uk

Many thanks, will check out their website!

[Nos4r2]

Originally Posted by xpertski

Many thanks, will check out their website!

They are VERY useful indeed.
For example, I had the instruments on my Ballistic on foamed silicone gaskets made from sheets supplied by them instead of sikaflexing them.

[xpertski]

Update: Heldite is brilliant! Took both Wema flange/gasket kits off and refitted with this stuff, tightened it more than before but still hand tight, and tested this morning, completely water tight [emoji106]

Heldite is messy stuff as PD says, sticky and gloopy! Bit of a juggle getting it down without getting mess everywhere but just about managed it with only the occasional bad word when dropping the inside bracket into the tank or getting Heldite where not intended. All cleaned up and looking tidy now though!

Used Loctite 577 thread sealer for the screws with 7649 activator in the holes using cotton buds (careful and one/two dips only as the cotton buds fall apart quick). Activator has copper in it and needs to be applied to plastic surfaces to help the 577 go off, it needs metal on metal contact to go off properly.

Thanks all for the advice on this, very much appreciated.

[Pikey Dave]

Originally Posted by xpertski

Update: Heldite is brilliant! Took both Wema flange/gasket kits off and refitted with this stuff, tightened it more than before but still hand tight, and tested this morning, completely water tight [emoji106]

Heldite is messy stuff as PD says, sticky and gloopy! Bit of a juggle getting it down without getting mess everywhere but just about managed it with only the occasional bad word when dropping the inside bracket into the tank or getting Heldite where not intended. All cleaned up and looking tidy now though!

Used Loctite 577 thread sealer for the screws with 7649 activator in the holes using cotton buds (careful and one/two dips only as the cotton buds fall apart quick). Activator has copper in it and needs to be applied to plastic surfaces to help the 577 go off, it needs metal on metal contact to go off properly.

Thanks all for the advice on this, very much appreciated.

Glad you’re sorted[emoji106]