mk1 petrol tank cleaning the rust out

[kevs 1961 mk1]

hi had a look inside my mk1 tank and its not too bad has some surface rust and some sludge at the bottom ,whats best to loosen/get rid of the rust, ive also heard you can coat the inside of the tank with some kind of seal stuff ,but how would that work as there is a filter in the tank and surely the seal stuff would block it ,any ideas would be gr8 thankyou

[MiNiKiN]

Depending on the amount and depth of rust I would use citric acid or (better) phosphoric acid.
If you got deep rust first add two or three hands full of fishing "lead ball thingies" and attach the tank to a concrete mixer and leave it rotating for some hours.
Remove the lead remains (dispose of acc. to your local regulations - Lead is carcinogen and poisonous!) and avoid the tank seal paint - it's only going to cause you grief in the futuire, when it comes loose.

[woodypup59]

I'm cleaning one at the moment.

It 2" thick sludge in the bottom and was rusty as well, after 20 years resting.

I pressure washed it and filled it with hot water and De-Ox.

I kept it as warm as poss, and when I emptied it out a week later the improvement was amazing.

The difficult bit was sealing the cap/neck it well enough to have it upside down.

[kevs 1961 mk1]

thanks I think il have a go at it over the wk end, got some old chain ,and il get some deox and try that

[dklawson]

Before you think about chemically cleaning a tank... ask if it is really necessary. You can rinse a lot of evils out of the tank using caustic cleaners and water. If you stop with the caustic cleaners and a fresh water rinse most the debris and gum will be removed without opening up pinholes which require more attention (like lining).

I encourage you to read the cleaning and prep instructions for products like: POR-15 tank liner, Kreem tank liner, Red Kote tank liner, and Caswell Epoxy tank liner. You'll find the instructions and prep chemicals are similar between the kits. However, avoid lining the tank unless you have to.

I agree about tumbling the tank if you are trying to remove some really stubborn rust or deposits. However, I would not use the lead balls mentioned earlier. It's fairly common to use lengths of chain, gravel, or old nut and bolts instead. Using old nuts and bolts has the advantage that they can come away from the process much cleaner and be worth using again.

[kevs 1961 mk1]

Before you think about chemically cleaning a tank... ask if it is really necessary. You can rinse a lot of evils out of the tank using caustic cleaners and water. If you stop with the caustic cleaners and a fresh water rinse most the debris and gum will be removed without opening up pinholes which require more attention (like lining).

I encourage you to read the cleaning and prep instructions for products like: POR-15 tank liner, Kreem tank liner, Red Kote tank liner, and Caswell Epoxy tank liner. You'll find the instructions and prep chemicals are similar between the kits. However, avoid lining the tank unless you have to.

I agree about tumbling the tank if you are trying to remove some really stubborn rust or deposits. However, I would not use the lead balls mentioned earlier. It's fairly common to use lengths of chain, gravel, or old nut and bolts instead. Using old nuts and bolts has the advantage that they can come away from the process much cleaner and be worth using again.

thanks for your reply il try some kind of caustic cleaner ,which would you recommend ? someone on another forum mentioned caustic soda

[dklawson]

...il try some kind of caustic cleaner ,which would you recommend ? someone on another forum mentioned caustic soda

Caustic soda is Lye. While it would work it is dangerous and I would not use it. However, it is your decision.

Unless you are located in the U.S. it is unlikely that you will have access to what I use. I use a product called ZEP Industrial Purple Degreaser. It is sold by the gallon at local DIY/home centers. Even though it is not Lye... I use heavy rubber gloves with the ZEP degreaser. Without gloves it will ruin skin.

[InnoCooperExport]

Why would you avoid coating the tank unless absolutely necessary? I am about to clean out and coat my old Inno tank that has stood still for 20+ years. It's pretty grimey and flakey in there and had been advised to strip and coat it by a few different people who said it was the best thing for it. So I am curious to hear any arguments against it.

The case for it as I understand it with modern Ethanol fuels is that it can start to condense on the tank when it goes stale which can cause corrosion. Sealing it will stop that from happening, if done properly!

[MiNiKiN]

Why would you avoid coating the tank unless absolutely necessary? I am about to clean out and coat my old Inno tank that has stood still for 20+ years. It's pretty grimey and flakey in there and had been advised to strip and coat it by a few different people who said it was the best thing for it. So I am curious to hear any arguments against it.

The case for it as I understand it with modern Ethanol fuels is that it can start to condense on the tank when it goes stale which can cause corrosion. Sealing it will stop that from happening, if done properly!

If the surface is not entirely rust- and grime-free you might get the coating come loose over time (happened to a few mates on motorcycle tanks) and then you have lumps of coating blocking your fuel line - try getting that remaining coating off from the tank - good luck.
I'd rather leave the tank blank and ever so often add a few drops of 2-stroke oil for preservation, or add fuel stabiliser for longer periods.

BTW: The beauty of the lead balls (sinkers) and concrete mixer method is that they leave a fine lead coating on the tank surface which imho additionaly protects.

No offense, but degreaser is pointless when it comes to rusty tank insides. As I mentioned I'd use phosphoric acid (i.e. a products similar to 'Tiger Rost-KO', available here in Austria) or citric acid which is available at the baking area of your supermarket and pretty harmless.
Takes some patience, but I have had really good results with the latter on various tanks.

[woodypup59]

The trouble with coating the inside of the tank is that it will coat the basket filter on the pick-up pipe.

Or have you got a clever way of preventing that ?

[CooperTune]

We fill the tanks with rock polishing media, nuts and bolts. I close the fill with a 2 inch rubber plumbing cap. I seal the sender opening with a proper rubber seal and flat plate cut correct size. Mount the tank on a gear box and rotate it for a couple of days remounting several times to get good coverage. Once the machine portion is done we have 5 gallons of Rustsolvo for a few days and if there are no holes we use it.

I have a couple of tanks at the shop that have been coated inside and the stuff is flaking off in sheets. Steve (CTR)

[Herbert]

The way to keep the inner filter clear is to blow an airline every hour. I used the product by FROSTs...fabulous stuff, but it takes a week to harden up into a rubber coating.
Fertan Tapox 2K Tank Sealer for 40L Tank : https://www.frost.co.uk/fertan-tapox-2k ... -40l-tank/

[InnoCooperExport]

The trouble with coating the inside of the tank is that it will coat the basket filter on the pick-up pipe.

Or have you got a clever way of preventing that ?

Do you mean during the coating, or afterwards?

For during the coating I will simply remove the whole pickup and sender unit and blank off the hole with something to keep it from running out, thereby avoiding the whole thing (though the pickup and sender in the same removable part may be an Inno quirk). For afterwards, a well cured coating shouldn't come off and block the pickup pipe at all so that shouldn't be an issue.

As for what MiniKin says about the condition of the tank pre-coat I completely agree, hence my caveat "if done properly".

The way to keep the inner filter clear is to blow an airline every hour. I used the product by FROSTs...fabulous stuff, but it takes a week to harden up into a rubber coating.
Fertan Tapox 2K Tank Sealer for 40L Tank : https://www.frost.co.uk/fertan-tapox-2k ... -40l-tank/

I actually have the Fertan set ready and waiting to go. Just need to line up a few days where I can do the strip and coat in a few consecutive days to prevent any fly rust forming between stripping and coating.

[woodypup59]

For during the coating I will simply remove the whole pickup and sender unit and blank off the hole with something to keep it from running out, thereby avoiding the whole thing (though the pickup and sender in the same removable part may be an Inno quirk). For afterwards, a well cured coating shouldn't come off and block the pickup pipe at all so that shouldn't be an issue.

I was thinking of early tanks where the pickup pipe is brazed into the base of the tank. The one I'm cleaning atm is from a '72.

[Dr.Mabo]

The trouble with coating the inside of the tank is that it will coat the basket filter on the pick-up pipe.

Or have you got a clever way of preventing that ?

I already coated 5 MK1 tanks with CREAM ROT. 3 left and 2 right tanks. I couldn't find a way to remove the filter, without distroying it. The filter is placed on the pick-up pipe before it was installed to the tank. So it has to stay in the tank during coating.
At the first and second tank I was able to put a little plastic bag over the filter. This was a quite difficult task to manage with some home made extension tools, but it works. On the other tanks I wasn't able to cover the filter, even not with the extension tools. I solved the problem by les coating in the tank. Basically the coating procedure is focusing on motorcycle tanks with nothing left in the tank. The coating instruction tells you to fill the tank comletely with the coating stuff and to remove the surplus fluid. This works with 5 or 7 liters motorcycle tanks but not with 25 liters car tanks. Thus I just filled the amount of coating into the tank i needed and moved the tank by hand. While moving by hand you can control where the fluid runs. When almost every corner is coverd then I moved the tank upwards so that the rest of the coating can run under the filter without reaching the grid.

I did the first tanks some 15 years ago and the coating is still working fine.