Petrol tank restoration

Dean,

As I live in Somerset I used JBS Motorcycle Painting, who are near Yeovil and they did an excellent job.  But, they don't undertake the chroming.

For the chroming I used S&T Electroplating at Yate, just north of Bristol.  Their chroming plating isn't cheap, but is very good.

.. put any sort of lining in it. If you're having a full restoration done, I'd identify any leaks and have them properly welded up.

Ethanol, despite rumours, won't damage your steel tank.

Interesting statement - "Ethanol, despite the rumours, won't damage your steel tank"

Ethanol might not, but it absorbs moisture, which then drops out and rusts the tank. Normally above the fuel level, as it creates its own moist atmosphere.

Even 'modern day' bikes suffer with steel tanks rusting, the rust gets in the fuel lines and blocks the carbs, jets filters etc. A local tuner to me is advising putting a small amount of two stroke oil in the tank to combat the problem and always keep the tank full when laid up.

Colin is absolutely correct, and ethanol in petrol can certainly cause the inside of steel tanks to corrode. Although the end result is the same, I think the mechanism is such that it doesn't need moisture to 'drop' out of solution and it doesn't create a moist atmosphere inside the tank. Ethanol will strip moisture from the atmosphere (the ethanol used in petrol is anhydrous, so think of it like brake fluid: it will absorb water vapour from the atmosphere) and it will then hold the moisture in solution in the petrol. The same as sugar in tea or coffee. The presence of the moisture is enough to support corrosion - and incidentally is one of the reasons why old fuel goes 'off' after an extended period of time left in a tank. Although the corrosion might be most noticeable at the liquid surface line, it can occur anywhere where the petrol (actually petrol + a small amount of water) is in contact with the steel tank innards. The liquid surface line is where the fuel sloshes about, and where there is a lot (relatively) of moisture in the free air, but corrosion can appear anywhere including in the tank's base.

Lining a tank is one solution, but fuel additives are continually evolving and who is to say what will be compatible with the fuels of 10 years in the future. There are still two solutions:

1. use ethanol-free petrol. Tomes have been written on this topic, but it should be available in SW England.
2. drain the petrol tank after use, or at least don't leave petrol in there for weeks or months while it goes off. Plenty of people do this, including the NMM although partly (for obvious unfortunate reasons) for fire risk and insurance purposes.

hello all now with COVID -19  still around  all Chromers  will be fully book out for the next ten weeks  like quality chrome in Hull and every Chromers around in Yorkshire And I think the rest of the country will be the same  and some may never reopen and have Already gone out of Business   So you may have a very long wait of your hands   Yours  Anna J  

.. modern petrol has never damaged any of my steel tanks and they haven't gone rusty inside. I wish people would stop repeating stuff they've read on the web.

WRT petrol "going off" I recently started my ES2 after it lying idle since September last year and with half a tank of petrol left in it. Started first kick and ran like a bird. I took the jets out to look at them and they were like new. The tank (as they always did) had a light coating of rust.

But waste your money and expect problems in the future with tank lining if you must. It's your bike. Although I pity any future owner.

You may like to read the posts I've put here about experimenting with petrol and carb components.

I agree with you Ian, my strimmer starts every year after a 6 month layup! However I have found that you can get green goop building up in the carb if you leave it for over a year! I only empty  out my glassfibre tanks, everything else is fine.  

Dan 

.. probably the grass!

Look any water that ethanol pulls into it by hygroscopic attraction, sinks to the bottom of the tank as water is denser than fuel or ethanol, hence the Duke of Clarence story, n in a Vat of alcohol, because as you cannot swim in alcohol, it will not support your body weight, as much lighter than water.

From the surface of the fuel the more volatile parts evaporate away, hence fuel level drops slightly with no usage and the steel above the fuel level starts to corrode.

The main reported damage is at the bottom of tanks, which may have stood for a long while, this is the problem for owners of  "Trailer Queen", specials, in that they are rarely started never used, (too precious), and just corrode away!

Also anywhere that has had features joined in , filler-cap hole, breather tubes,  tank seams corrode first, with or without ethanol!

John

.. that the ethanol "pulls in" water. It didn't in the case of my small experiment and the water I deliberately introduced stayed at the bottom well separated from the petrol above.

And it was a butt of malmsey which was a fortified wine a bit like port or sherry, not pure alcohol. I don't think there would have been room to swim....

• Like leprechauns, and faeries, ethanol only causes problems for believers!  My bike, and various petrol driven machines NEVER have their tanks drained, and often stand unused for months.     10% ethanol caused no problems in the 50's, and (as my bike is of that era) causes  none now.           Possibly the composition of some plastics has changed ,over the years, and may not be resistant to ethanol.         However, just as unleaded petrol was predicted to destroy older engines (it didn't!), ethanol is being blamed for every unexplained fuel problem.  The main cause of water in the tank is condensation, regardless of what fuel is used.

I ran the Stag I mentioned earlier on unleaded and did around 50,000 miles on it. I checked the valve clearances religiously every thousand miles or so to start with but they never moved.

The engines that were affected by unleaded tended to be those with cast iron heads and no hardened valve seats but even those are fine as long as not enthusiastically reground.

hello this thread start with restoration of a Norton fuel tank and not unleaded fuel  witch I give a extensive report on this topic well over five years ago a no one paid any attention to   the  first thing to restore a tank is the get it clean inside and out,    and assess any damage  and repair costs  yours  anna j  

Anecdotal evidence is fine from people who have been driving for 120 years and have never had any problems with any fuel or fuel tanks, but there IS some science there that can't be ignored.  There will always be people who have led a charmed life and haven't been affected by whatever subject comes up, but water in fuel tanks is a fact and applies to petrol and diesel tanks.  

Ethanol is hygroscopic ("Hydrogen bonding causes pure ethanol to be hygroscopic to the extent that it readily absorbs water from the air.")  so it can only add to any condensation/water problems - ergo, rusty fuel tanks.  It is well known that diesel tanks, in particular, should be kept as full as possible so that there is less room for water vapour.  This applies to petrol tanks too.  Diesels are lucky enough to have water filters so it's less of a problem.

As to unleaded petrol - it is well-known that alloy heads with hardened valve seats are unlikely to get problems with seat recession - but an additive might be "belt and braces".

Tanks can be repaired with plumber's solder.  My Dad repaired the rust hole in the bottom of my 1955 tank in about 1964 an it's still there!  He used Baker's Fluid as a soldering flux and probably plumber's solder from a coil.

Some time ago I reminded people that you can use plumbing solder to repair and fill steel.  It was standard practice on car body panels and used at the manufacturers to cover welded seams.