Rusty Petrol Tank: Advice Required Please

If it were my tank the first thing to do would be to empty the contents and let it dry out, then wrap the exterior in cling film to protect it.

Next I would drop a handful of stainless nuts and bolts into the tank and shake it all about. This will deal with the loose stuff you need to shake out.

Once as clean as possible I would use either the Wildes ethanol resistant Flow Liner or Slosh sealant but first use their tank cleaner / preparation fluid. (You can buy the kit)

You will need to seal the tank during the cleaning /sealing process. I keep a kit of an old tank cap and 1/4 BSP short set screws but there are other ways.

Other owners / restorers have their own preferences and I respect that as long as what you do works.

I would advise using E0 petrol if you want to look after your tank and fuel system in the long term. Avoid EN228.

I have had to do a number of tanks, I agree with Neil as to protecting the tank paintwork but I would strongley recommend once you have flailed the inside as suggested you then use the complete kit of sustances before lining it [if this is what you wish to do,] I use POR15 and the associated chemicals, however the Velo I have the P/O used 'slosh' as Neil says it doesn't matter as long as it works for you, but don't be to impatient or you will be wasting your time. kind regards

Do you chaps recommend sealing it if it is not actually leaking? Isn't there some sort of phosphoric acid treatment to stabilise it? Shouldn't chemicals be a last resort?

Anti rust treatments are good but if the tank is not leaking I would not use any sealer as there is little to prevent the fuel makers using any chemical they like, so whatever works today may not work next week.I saw the spec of what goes in to our fuel and the list was endless. If its not broke don't mess with it.

I had a similar tank, after the nut and bolt shake around I left it for a week full to the brim with diet value coke from Tesco. I then pressure washed it, rinsed it out with alcohol and dried it quickly to stop flash rusting. Put in a gallon of 2 stroke swished it around and job done. I still run an in line filter just in case!

"there is little to prevent the fuel makers using any chemical they like"

Absolutely true and why I wouldn't use any sealant at all. Remember when we all got excited about unleaded - nobody thought we'd have the odd cocktail we've now ended up with. And for what it's worth, I don't believe it's ethanol that's the problem but some of the other strange ingredients. Ethanol is blamed for rotting cork and copper components but remember that it's the "active ingredient" in whisky which is made in copper stills and kept in bottles with corks.

In the 1950s there were several petrols, including Cleveland Discol which had quite high quantities of ethanol which was supplied by Distillers Ltd and I don't believe it caused any problems.

A weak solution of phosphoric acid should clean up the inside.

Phosphoric acid is the active ingredient in the Coke application but the Coke is very weak. Go to a chemist to see what you can get.

Mike

Ethanol turned my petseal to a sticky substance (Needle sticking) & I am 100% certain this was a result of ethanol, during 2006/2007.

However, the petseal contained inhibitors that protected the inside of the tank and after the removal of the ethanol contaminated petseal the inside of the tank, as much as I could see was perfect and shiny. I never, after that had need to use a tank sealer in those two tanks.

My 16 H tank was treated with the same pet seal in 1997 and remains in perfect condition. It has never had ethanol near it, nor will it or any of my bikes.

The only pump petrol you can be sure of not containing ethanol (Yes mistakes can happen with delivery) is ESSO Supreme Synergy+ (97 RON) with a red label. This is not available in Devon and Cornwall, Teesside ethanol zone (It goes all the way South to Ripon) and Scotland. Look for the red label.

You can of course use EN228 but don't say I didn't warn you.

Lifting the needle...

I used Diet Coke exactly because it is dilute phosphoric acid that you can pour down the drain when youâve finished but the rust was fairly light. On another tank I used milk stone remover ( conc phosphoric acid) from an agricultural store (mole valley .... others are available!) you dilute it about 4 to one and it took about an hour, however you have to be careful itâs strong stuff and I needed a kilo of bicarbonate of soda to neutralise it afterwards. I also had more of a job preventing the flash rusting. Do it on a warm day and have plenty of isopropyl alcohol available to wash it out.

Next time Iâm using value Diet Coke again (no sticky sugar) it was less than £3 for 3 gallons as I recall! Even if I have to change it a couple of times.

if you google it there are a number of ways Iâd doing it, one way I havenât tried is putting in abrasive material - from broken windscreens to nuts and bolts then bubble wrap the tank and jam it in the tumble dryer and leave it on cold for an hour or two. I might try that on another tank but am worried about getting all the grit out. I think flash rusting will be less of a problem that way, although it will need to be pressure washed afterwards I think.

My advice is start with the easy ways first and move to stronger acids if that doesnât work. Iâd stay clear of hydrochloric or sulphuric acid ... too nasty!

Dan

Steel petrol tanks never had any coating in the old days. You have a couple of options once you get the inside clean if you don't want to line the tank. Keep it full or keep it empty and dried out when not using it.

Or just use E0 petrol and forget the hassle. Other fuel system components are also compromised by ethanol.

E0 gives you more MPG too, along with a much longer shelf life.

Needle sticking...

Previously david_evans wrote:

Steel petrol tanks never had any coating in the old days. You have a couple of options once you get the inside clean if you don't want to line the tank. Keep it full or keep it empty and dried out when not using it.

I agree but there was no coating in the old days but there was no ethanol in the fuel then. Ethanol has a greater affinity for absorbing water than petrol.

I wonder how many old tanks we still have around would have survived if most fuel was contaminated with ethanol back then, as it is today. Certainly NO fibreglass tanks, that's for sure.

ESSO Synergy Supreme+ (97 RON) is E0 but not in the 3 UK ethanol zones. SW, Teesside and Scotland.

Needle stuck.

If you want a phosphoric acid rust killer, try Jenolite. It's a concentrated semi-liquid, which you can dilute as desired. It can be used concentrated to neutralise heavy corrosion, or diluted to soak and pickle a component.

But with a rusty tank, use the nut n bolt method first

Paul

Previously michael_sullivan wrote:

A weak solution of phosphoric acid should clean up the inside.

Phosphoric acid is the active ingredient in the Coke application but the Coke is very weak. Go to a chemist to see what you can get.

Mike

Milkstone remover is cheaper I think, if you are anywhere near Devon you are welcome to some of mine!

Previously david_evans wrote:

I agree but there was no coating in the old days but there was no ethanol in the fuel then. Ethanol has a greater affinity for absorbing water than petrol.

Actually, there was. Cleveland Discol which was very popular in the 1950s, had 10% ethanol supplied by Distillers Co. And I'm not aware of any complaints.

I believe the problems with modern fuels are more likely to be caused by the cocktail of other stuff like benzene which is added.

as an aside, I often think you don't get rusty 2stroke tanks, or do you , is it because the bikes didn't last the ravages of youthful exuberance perhaps? and would the addition of a drop or two of oil added to the petrol, preferable Castrol 'R' help prevent the effects of sodding ethenol etc? kind regards

If your tank is full then it shouldn't rust because the oxygen can't reach the surface.

Previously ian_soady wrote:

Previously david_evans wrote:

I agree but there was no coating in the old days but there was no ethanol in the fuel then. Ethanol has a greater affinity for absorbing water than petrol.

Actually, there was. Cleveland Discol which was very popular in the 1950s, had 10% ethanol supplied by Distillers Co. And I'm not aware of any complaints.

I believe the problems with modern fuels are more likely to be caused by the cocktail of other stuff like benzene which is added.

Ian, I have said this before but I need to say it one more time: Back in the day there were very few machines laying about unused for weeks, giving ethanol time to attack components. In addition, most fuel was E0 and so even if a vehicle was left with fuel in the tank it would unlikely have a significant amount of ethanol in it, if any at all. Today however nearly all pump fuel is contaminated with ethanol. We know the damage it causes and now discovering the pollution too but the ethanol remains in order to meet government renewable energy targets!

Needle stuck.

Previously david_evans wrote:

If your tank is full then it shouldn't rust because the oxygen can't reach the surface.

Interesting point. Why do prams and push bikes etc rust at the bottom of canals and lakes?

It is quite common for modern steel tanks to rust at the bottom even when in regular use. Maybe more to do with blocked filler drains than ethanol but the ethanol contributes surely as it will hold 50 times more water than petrol.

I personally have had poor results with internal coatings. I'm not saying good results aren't possible, only that I did my best to follow the directions and the result was poor coverage and failure of the coating. I ended up with a glass inline filter that I emptied of coating bits now and again.

Surprisingly I've gotten good results with vinegar. The first time I tried it was really just to prove that it didn't work. Instead, after soaking for two or three day I had nice, gray metal which I then cleaned and coated with light oil which prevented rust until it was in use.

None of my bikes have original paint so leaks get fixed with a torch.