Petrol Tank - somewhat rusty/cruddy inside - quick fix ?

[hoogerbooger]

I was hoping to get my B40f on the road initially with the minimum of tinkering ( then have a more concerted effort at restoring next winter - when I'm feeling braver).

My tank ( pics attached) has chips & a few rust bubbles on the outside and some rust and crud inside. Looks like the tank was sealed with something by the previous owner but this was 20/21+ years ago. The bike last ran 18 years ago on leaded.

I've just been viewing youtube on using the POR15 kit .... but that would seem best done when/once I've repainted the tank.....which I wasn't hoping to do now.   Is there a quicker fix in the interim just to wash out the crud ?  if so any advise on technique ? I was hoping that using a fuel additive like Millers VSPE Power Plus might then get me by with the ethanol resistance ?

[AWJDThumper]

Normally, rust removal from inside the tank is straightforward unless sealant has been used. If it has then it has to be removed before de-rusting. I've got a similar tank to do and the best way to protect the tank during the process is to cover it in cling film. I will then use strong paint remover poured and swilled around the inside the tank to dissolve the sealant. Sometimes it can take quite a bit of effort to remove the old sealant but has to be done if you want to properly de-rust it. Swill out when necessary with plenty of water using a hose pipe.

[hoogerbooger]

How can I be sure if sealant has or hasn't been used ? Is it just a case of anything inside that looks like a paint coating is a sealant ....... & if it wasn't sealed it'd look metallic or rusty ?

also  I'm wondering if I don't know how to measure Imperially !!   as measuring the threaded opening that the tap was in, it would seem to be 5/8" (16mm).This doesn't seem to match anything I've found so far online.  (draganfly have the part listed as: Petrol tap, 3/8x3/16, back entry, reserve only, with filter 68-8024).  So were there tanks with 5/8" outlets & whee are the 5/8 taps?

Will all imperial bolts have the same thread ? (as I'll need to find one to block the outlet if I clean and seal it).


(Wishing now I had myself a small imperial nut & bolt set..... to check & convince myself on the right fittings).

[A10 JWO]

Sorry to jump on the thread, mine is similar in as much as it sat with stale petrol in it for years. No rust but a  sediment  type of coating inside I was going to soak it with a mixture of clean petrol and paraffin for a week or so ? would this work ? Thanks.

[Phil C]

Like A10 JWO, sorry to jump on the thread. Mine (see photo) looks similar to hoogerbooger's. Is that a coating/sealant of some kind, or bare metal? I'm thinking it might be bare metal? Also, I assume the dark spots are rust. Would they get significantly worse even when covered with fuel, or would the fuel protect them by preventing much air or water getting to them (I believe rust needs air and water?)   Phil.

[JulianS]

Petrol tap thread is 3/8 BSP.

[AWJDThumper]

I've cleaned up a lot of tanks and the most difficult have been when someone has used a sealant on top of rust - this seems to happen a lot and some of the older types of sealant can be difficult to spot. It's always best to start by trying to remove as much of the rust or crud as you can by giving the tank a good shake with pebbles or nuts inside followed by a good wash out with soapy water or other solvent to clean and degrease it, followed by a good rinse with a hose pipe.

Since you can't always spot the presence of sealant, you sometimes need to try a rust removing liquid first to see how effective it is. With the liquid I use, I normally have to leave it in the tank for up to a week. If there is no sealant present, the liquid will remove all the rust. If it doesn't, then there is probably sealant present.

I remove sealant with paint stripper after protecting the tank if necessary with cling film. Depending on what sealant has been used, this can take a number of days to dissolve and it can be difficult to tell when it's all gone. Sometimes you can only tell when the sealant has gone after re-applying the rust removing liquid and seeing whether it completely removes the rust. If not, more paint stripper might have to be used followed by another stage of rust removal.

Once all the rust has gone then the use of POR-15 sealant is very effective.

[RobinG]

I've had success in the past cleaning rusty tanks by electrolysis. If you look on you tube or google it there are several examples of how to do it. It will shift rust on a tank that has not been internally coated with sealant. All you need is some washing soda, a battery charger and a piece of scrap steel.
Sounds a bit strange at know, but it does work surprisingly well.


Robin

[Mike Farmer]

 

I find that once you knock the lumps of rust out, by whatever means, the electrolysis method is good.

You will need: - a plastic receptacle large enough to hold your item with some extra space.
                       a battery charger
                       A lump of iron (For big stuff I use an old brake disc) called the annode???
                       A slack handful of kitchen soda.   
                       Warm water.

Method: -    Dissolve the soda in the warm water enough to cover at least most of your rusty bit.
                  Connect the rusty oblect to the negative terminal.
                  Connect your lump of iron to the positiv terminal
                  Ensure the two are not touching(or kiss goodbye to your charger)
                  Switch on after a short time you will start to see a line of bubbles 'tracking' on the surface between the two items.
                  You will then see the rust start to surface it will bring with it a lot of other *rap.



.
                  Ensure that your item and your lump are not touching(or kiss goodbye to your charger)

[Phil C]

What would be a good rust-removing liquid for patches like this (see photo)? Doesn't seem severe/widespread enough to necessitate techniques such as electrolysis?

Also, will it get worse even with petrol in it, or will the petrol prevent the rust getting worse?

Phil.

[Greybeard]

If your main concern is getting the bike on the road for this summer (if we get one  ) then I would suggest that giving your tank a good swill out to remove loose muck is as much as you need to do for the time being. It'll not get noticeably any worse for a while. Its water contamination in the fuel that causes the rust and ethanol absorbs it from the air, hence the problem makes itself known quicker than it used to - unless you can track down ethanol free fuel - my local BP garage's ordinary petrol is fine - or use what's in there faster so it has less chance to absorb the water 
Tank restoration, done properly, is quite time consuming and not by any means a quick fix. Personally I wouldnt spend the brass doing half a job. If you're going to restore the bike anyway, then doing the inside of the tank first saves any worry about marking the paintwork.
Ive done a few tanks now, both mine and for mates, and have found that POR15 is the easiest to use. Tapox is a bit thin and watery, and whilst probably ok, I was happier with two coats in my AJS 650 tank. Time will tell. Tank Care Products, which I used in my Matchless G80 tank gives a good coating but is very temperature sensitive in terms of flowing well. Too warm and it goes off too quickly, too cold and it stops flowing. Never used it again though I did get two kits intending to do the G9.
My method starts by giving the tank a good slosh with hot degreaser. POR do one but its expensive. Halford alloy wheelcleaner diluted about 3 to 1 gives good results, though if you fancy the challenge, caustic soda is even cheaper - just be careful!
If there is a sealant already in there, then Sealeater is excellent. Around 25 quid a litre which is enough to do two heavily sealed tanks. Use about 250ml, dont breathe it in, and close the lid. Leave it alone for up to a week. The sealeater breaks down the old epoxy into what looks like cornflakes that are dry and can be shaken out. Another wash with degreaser will shift the dregs. Occasionally, if a tank has been sealed in a hamfisted way, like my AJS tank, it can take over a fortnight to break down very thick layers of sealer. That had great gobs over half inch thick in the bottom but they gave up eventually.
Once the tank has been cleared of sealant then rust removal is next. I use a product called Jebsol 62, which i can get locally atround 30 quid for a 5 gallon drum. Its just phosphoric acid initially produced for cleaning ali milk churns. About a gallon, diluted at 4 to 1 sloshed around the tank will remove every trace of rust. If you dont feel inclinded to swirl it around the tank every half hour or so for a day then simply top the tank up to the brim and leave it overnight. Phosphoric acid wont eat through the steel like hydrochloric does and doesnt damage paintwork etc so is safer to work with.
Once youre happy that all the rust has gone then your next task is to rinse out the tank and dry it before any flash rusting of the wet steel gets a look in. A litre bottle of isopropyl alchohol (rubbing alcohol) is cheap, and tipped into the tank soon takes up any free water. Tipped out, its then just a question of using an airline with a high pressure jet to rapidly dry out the tank.
Its then simply a question of using your chosen sealant to finish the job.
I have tried other chemicals to remove the rust, fertan was one, which i found distinctly unimpressive as it left a loosely adhering purple coloured deposit on the metal that didnt inspire confidence.
Kits are available which do the above but are expensive for what you get, though they do work.
You pays yer money and yer takes yer chance 

If youre anywhere near East Yorks Ill be happy to assist.
Steve

[Phil C]

Thanks very much for this, Steve. I'm a long way from you - South Devon. I'm not sure there is a coating in mine - looks a bit like it's maybe been blasted in some way? I could be wrong of course.  Phil.

[hoogerbooger]

Thanks Steve.  Your advice matches what my mind had begrudgingly concluded.  Clean and seal the tank inside properly now. ( But Paintwork on the outside of the tank can wait til later)

For simplicity of supply & instructions I think the POR15 Bike Tank Repair kit  (£50) is the way I'll go ( unless others know of problems with it).   

[I'm in mid Wales -  but thank you for the offer of helping us novices  - no sign of spring or summer from here either - sheep are in the pub by the fire]

[Phil C]

Do any fuel additives help prevent/limit the rust?  Phil.

[Greybeard]

Millers VSP claims to help. I use it just to keep the petrol fresher. Its also reckoned to be an octane booster. It seems to work in the fuel I keep for the outboard of my sail boat. I tend not to use a great deal though as the engine is only used for manoeuvring on and off jetties if the winds a bit contrary. A gallon has lasted 3 years for that with no ill effects and all the bikes appear happy with it 
The best remedy of course is to keep using the fuel by riding regularly. That way it doesnt get chance to take up much in the way of water or go stale.

Steve