Plastic tank Swelling and Pimples

[Nasher]

I've been having quite a lot of trouble with the Plastic tank swelling on my M1000, the only cure for which appears to be airing it for a few months without any fuel in, so having two tanks I've been swapping them out every 6-12 months.
I really don't like the thought of trying to coat the inside, as whatever you put in is REALLY hard to get out again.

A couple of years ago I brought another tank from Slob, repainted it, added new Decals, then decided the Satin Black look I'd gone for wasn't actually that great, but have been using it on the bike as above.

Then on Friday when the sun was out I tried to take the bike out for a ride and found the fuel pump had given up the ghost.
I took my 999 out for a ride instead, but decided as the tank had to come off anyway, and the tank had swelled again, I might as well swap the tanks over.
the tank on the bike was the original with the original paint.

I must admit I was a little shocked at just how much bigger the old tank was this time, but unfortunately I think I've left it too long because the paint on the old tank has blistered really badly, even in places that don't always have fuel directly behind them when on the bike.

I say blistered, but they appear more like pimples, and are hard. I've not tried too hard to pop any as I don't want to break the paint layer.
Strangely they appear to be in lines in places.











Is this normal?

[Mr Gazza]

I think that is fairly normal from the ones I've seen that suffer with it.
I bet the wailing and Nashering of teeth is fairly normal too! (see what I did there? )

It does seem to be higher up the tank on the side stand side and possibly reflects the fuel level when parked? Although academic at this stage!

Once it's gotten into the paint it's quite advanced and I don't think there is a way back, although it's definitely worth waiting to see how it dries out.
I'm with you regarding the internal coatings. I loath them! All I would say is that if you are considering that, (which I doubt) then get it done by a professional who will guarantee their work properly.

You've probably already seen that Moco got himself an alloy tank for his S2R1000.
I think that's the only way forward if it's a keeper?

[Jam911]

This post made me immediately go out to the garage and check my tank.

All good.

[motomartin11]

That looks awful. Almost makes me glad I have a metal tank-but see my misfire thread to see how I too have come unstuck with that! It seems you just cannot win with so called modern fuel, and fuel tanks.

[Nasher]

Thanks Guys.

An Ali tank would be great Mr G, apart from the expense, but I might just have to go down that route.
Of course going down the Steel tank route brings with it other issues, like the bottom rotting out.

I see what you are saying about the pimples being higher/worse on the stand side, but it's actually hardly ever on the side stand.
It might be for 1/2hr whilst I have a Coffee whilst out, but all the time it's in my garage it's upright on a paddock stand.
Perhaps it's still a legacy from the previous owner from a couple of years ago or so.

Like you suggest, I'm a little bit resigned to the fact that it's going to need a repaint now.

[Nasher]

In my head there is another option with an Ali tank, but I do need to put some more effort into working out if it will be significantly cheaper.

To my mind the major expense of an Ali tank is getting the complex curves in place, welding the panels together and finished to an acceptable standard. The use of an English wheel and proper time served Panel beating skills on Aluminium don't come cheap.

On the other hand, welding a multitude of flat Ali panels together to be fuel tight is skillful but quicker and a little easier to achieve.
My TIG welding is not up to doing the whole job, but I could cut the panels and possibly tack some of it together ready.
Then, I am very confident in taking a mold off a tank to produce a Fibreglass cover and finishing that to a high standard. A bit like more modern bikes.

Hi Nasher, Yep I feel your pain, mine is exactly the same mate, like MRG said higher up the thread I went all in for an alloy version as all plastics will go that way eventually.

I did track down a spare second hand plastic one but it needed a re spray so in the best tradition of indecisiveness changed my mind and went alloy !

[Mr Gazza]

Originally Posted by Nasher

Then, I am very confident in taking a mould off a tank to produce a Fibreglass cover and finishing that to a high standard.

.. Or cut the bottom out of one of your plastic tanks and bend the ali into it to form the top. Then use the bottom as a form for the ali bottom. You already have the pump/filter assy on a plate.
It would need a clever new filler neck to join the tank to the cover. But you'd be using the same cap with the key.
No need to make a fibreglass cover as you already have the bottomless plastic one.(now in need of a re-spray! But never to be affected by fuel again.)

If you cut it in the right place it would spring over the ali tank and you'd still use the rubber frame feet.

[Luddite]

That's a real bummer, Simon. I know those earlier white plastic tanks like yours were made by Acerbis from PA6 nylon.



That stuff is hydrophilic and so absorbs water. It's not actually the ethanol directly that attacks the tank but rather the water drawn out of the petrol by the ethanol, which then gets absorbed by the tank. (It's all a bit academic I know as a ruined tank is a ruined tank no matter what the cause.) The water absorption causes the swelling and the blistering is probably water migrating through the nylon and emerging under the paint.

While the dimensional change should (as you've found in the past) be reversible, I'm not sure about the blisters as I'd have thought that once the paint had lifted from the tank, there would be nothing to make it adhere again to the surface even if all the moisture has been removed.

You're quite welcome to borrow my dehumidifier to speed up the drying process if you like.

By the way, I take it you weren't using Esso Synergy Supreme+ ethanol-free in this tank?

[jerry]

According to Esso all their UK fuels are now minimum 5% ethanol and they no longer supply ethanol free fuel as its illegal .

many plastic tanked Ducatis in Thailand have now been scrapped as uneconomic to repair , even though benzine pure ethanol free 95 is still available at about 30% of garages .

[Nasher]

Originally Posted by Mr Gazza

.. Or cut the bottom out of one of your plastic tanks and bend the ali into it to form the top. Then use the bottom as a form for the ali bottom. You already have the pump/filter assy on a plate.
It would need a clever new filler neck to join the tank to the cover. But you'd be using the same cap with the key.
No need to make a fibreglass cover as you already have the bottomless plastic one.(now in need of a re-spray! But never to be affected by fuel again.)

If you cut it in the right place it would spring over the ali tank and you'd still use the rubber frame feet.

Good idea Mr G.

I've also got another thought brewing but need to make some calls to confirm it's possible before making a prat of myself on here.

[Nasher]

Originally Posted by Luddite

That's a real bummer, Simon. I know those earlier white plastic tanks like yours were made by Acerbis from PA6 nylon.



That stuff is hydrophilic and so absorbs water. It's not actually the ethanol directly that attacks the tank but rather the water drawn out of the petrol by the ethanol, which then gets absorbed by the tank. (It's all a bit academic I know as a ruined tank is a ruined tank no matter what the cause.) The water absorption causes the swelling and the blistering is probably water migrating through the nylon and emerging under the paint.

While the dimensional change should (as you've found in the past) be reversible, I'm not sure about the blisters as I'd have thought that once the paint had lifted from the tank, there would be nothing to make it adhere again to the surface even if all the moisture has been removed.

You're quite welcome to borrow my dehumidifier to speed up the drying process if you like.

By the way, I take it you weren't using Esso Synergy Supreme+ ethanol-free in this tank?

Thanks mate.

Yep, I'm aware that the issue is the water, not directly the Ethanol, but the Ethanol just attracts more water.

I've been using E5 in all my bikes wherever possible, but have found that my local Morrisons have had the pump locked out occasionally so have had to put E 10 in.

The tank is now on a shelf in my storage container which despite being sealed has done the trick previously to shrink it back down.
I've removed the cap and Fuel pump assembly to air it.

I'm looking at a couple of solutions to try as a permanent fix, but not trying to line the tank with something that will peel of in places and stick like the proverbial in others.

[Nasher]

Originally Posted by jerry

many plastic tanked Ducatis in Thailand have now been scrapped as uneconomic to repair , even though benzine pure ethanol free 95 is still available at about 30% of garages .

What are they replacing the tanks with Jerry?

[Mr Gazza]

Looking at the pictures above, it looks like the bottom of the filler "well" is alloy already?
I wonder if it's possible to cut that out and clean it up well enough to weld to the ali inner tank?
It would then need the plastic outer sealing back down to it to prevent fuel leaks running down between the inner and outer and the cap would fit in the normal way.

I think the pump flange is metal too? so the same would apply.

[Dukedesmo]

Originally Posted by Nasher

Thanks Guys.

An Ali tank would be great Mr G, apart from the expense, but I might just have to go down that route.
Of course going down the Steel tank route brings with it other issues, like the bottom rotting out.

A nice ally tank would be great but there's nothing really wrong with steel tanks. All of my bikes have steel tanks and I've had no problem with rust in any of them and one of them's 44 years old.

I've only ever had 1 bike wth a plastic tank, a KTM 500 motocrosser, I think they were plastic from a practical POV; damage resistant, lightweight & cheap rather than any modern idea (it was an '80s bike). It wasn't painted, rather just plain white and it would 'sweat' fuel (previous owner had painted it and all the paint peeled off due to the fumes) but it was fine for an off-roader.