Petrol Tank

DIY, fill with vinegar or citric acid, leave for a day or so, drain and flush, repeat if rust still present. Once rust is gone flush with couple pints of meths to remove all water and leave to dry in a warm place.

Another method if your friendly local engineering shop has a caustic tank, have them put it in there for a day. This will remove everything. Afterwards wash it down and properly dry it out.

If you wish you could then treat the inside with something like Wylde's, especially if you are planning to put ethanol inside the tank.

The caustic will reveal any earlier repairs. Have fun preparing and repainting.Seal your paintwork to protect from E, if using it.  I have seen a lot of lovely paintwork ruined by this solvent. 

I have tried John's method, that works too...It was cider vinegar I used from Sainsbury's.

I follow Neil's route if I am planning to repaint as all the paint is removed. Not keen on lining the inside of steel tanks, formulation of petrol is not fixed, changes with the season and with legislation. Getting delaminated linings out of a tank is a pain, got the T shirt so never again. Either use E0 or drain tank before winter layup.

Hi John, I quite agree. My two slimline tanks have remained unlined since I managed to get the remaining pet seal out of them. (2006-08) I think that is how they will stay. The slosh in my 650 tank is starting to come away (Maybe down to me rushing the job) but the three tanks I have used Wylde's Fowliner on remain perfect.Time will tell but I like to leave my bikes full with E0. You just never know. BTW, I pet sealed my 16H tank in 1997, before contamination, never seen ethanol and the inside still perfect.

Even with the cheapest white vinegar I can see on the web, an interstate tank is going to cost about £50 to fill with vinegar, or £100 if two sessions are needed to clear the rust. Ouch !!

Hi Alan,

Yes, Sainsbury's made a fortune out of me, while the use of the caustic tank came for free.

Depends if you want to save your outside paintwork.  Incidentally, Wyldes sell as a part of a pack, if you want the whole works, that will prepare the inside of your tank, though I have never used it.

Hi Neil,

I got some stuff off Ebay for about £14. One litre makes 10 litres when diluted which is enough if you turn the tank every day or so until it`s back to bare metal all over inside. (to fill an interstate tank completely would be expensive and very heavy to lift) so propped the tank up against the bench and kept turning, checking with a torch until clean, rinsed out with hot water, blown out with airline, squirted inside with WD40, sorted.

Best wishes, Al.

Citric acid comes as a powder so a lot cheaper than vinegar. I used 1kg of powder to add to 4 gals for an Interpol tank. 

If the tank is bad then:

1. Strong caustic soda solution, sodium hydroxide also known as 'lye', not bicarbonate of soda. Mix from granules sold as drain cleaner in B&Q, Wilko (and other places), to degrease the tank. Fill tank with solution, leave to sit for a couple of days occasionally giving it a slosh around. Drain and rinse thoroughly with water. That it is sold as drain cleaner might give you an idea for how to dispose of it.
2. Brick cleaner from your local builder's merchant (£16 for 5 litres). It's a strong hydrochloric acid solution. Add to tank, slosh around and pour out. Note that all caustic must be rinsed out before adding acid. How long you leave it in the tank depends on the amount of corrosion. It will attack steel so better to leave for a few minutes at a time and repeat as required. Pour acid back into original container for next time. When satisfied, thoroughly flush tank with water to remove all trace of acid.
3. Dry tank, hair dryer works but check with the wife. It will start rusting as you look at it.
4. Pressure test tank, 4-5psi is plenty. A badly rusted tank is likely to have a few pin holes. Don't put any petrol in it until you're sure you won't need to weld it.

Warning - all these chemicals are dangerous, protective clothing and due care must be taken. E.g use outdoors, keep pets and children away, dispose of carefully, use long gloves and eye protection.

I have not damaged original paint finishes cleaning tanks this way - wash off spills on the outside immediately. Unfortunately can't say the same for brazing up pin holes.

Always add the chemical slowly with mixing to the required volume of water. Adding water to caustic soda pellets (or drain cleaner powder) will cause an extremely vigorous reaction and risk of severe burning or other injuries.

How about trying electrolosis for rust removal ??

I've used this for rust removal on other vehicles ( Land Rover ) and it certainly gets the rust off !!

The only trouble I see with any method of rust removal is the preventing of flash rusting afterwards, some sort of fuel proof plating would be required or indeed a tank liner otherwise you'll be back to square one in no time at all.

I have used electrolysis, it worked but was very messy and the iron nail suspended in the fluid needed cleaning a lot for the process to work. A flush with phosphoric acid will stop any rust bloom as it creates a very thin non porous layer of iron phosphate on the surface of the steel.

I used electrolysis on my Navigator tank and used a length of 1/2" studding with a bend at the top so when in the tank it went the full internal length. and a wooden plug to hold and isolet the bar. It worked well.

Milk stone remover is phosphoric acid and diluted works well (think Jenolite) but you’ll need some bicarbonate if you want to neutralise it. - get from Mole Valley Farmers etc.

Picking vinegar is £3 - £5 a gallon in tescos or on the net. 

I went down the old fashioned route of a handful of chains, nuts and bolts being inserted inside my Dominator tank and then shaken about for 5 minutes. This was then flushed out with a litre of petrol before a repeat of the former.

My tank was then allowed to dry out inside the green house during daylight hours before having a litre of rust bonder / converter goo thrown inside to coat the inner surfaces. The excess was poured out and the tank given 24 hours to dry, including another session keeping company with various plants in the green house.  The result was a black coating inside the tank which did not peel or flake. Total cost of around £10.  I added a small glass external filter in the fuel line which never showed any significant residue from the tank contents. Worked for me!!!

All good tips above, but to save you from doing anything; just use E 0 petrol.

EG: Esso Supreme Synergy 99 with the RED label, available in most of the UK.

Very long shelf life too.