Cleaning out fuel tank of Sq 4

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MikeEndicott
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Cleaning out fuel tank of Sq 4

Postby MikeEndicott » Sun Feb 24, 2019 11:37 am

Hi my wife and I have just agreed to buy a sq4.
One of the things that we noticed was that the inside of the fuel tank has seen better days. Almost like old rust from condensation when in storage. There also appears to be some sort of sealant residue in there as well.
Do you guys has any suggestions on how to best remove and clean this to its former glory?
Cheers mike

StewartPorter
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Re: Cleaning out fuel tank of Sq 4

Postby StewartPorter » Sun Feb 24, 2019 5:20 pm

http://www.realclassic.co.uk/techfiles/ ... moval.html
I used this method on my Triumph 5ta a couple of weeks ago with excellent results. Gonna do my rusty Sq4 tank soon too and repeat the process.
Good luck
Stewart
'59 D1Bantam, '60 5Ta Speed Twin, '76 Yamaha FS1-E, '58 Sq4 (Lazarus project)

john.whiting
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Re: Cleaning out fuel tank of Sq 4

Postby john.whiting » Mon Feb 25, 2019 1:23 am

I have always used sharp gravel well shaken with a hosing out every few minutes is best for a start.....about a jam tin full of gravel,the best is crushed blue metal,often used for driveways....When the tank is well shaken and plenty of water,you can then clearly see if there is sealant inside.........if there is significant rust in the seams,then small nails or screws will get rust out of seams...........my advice is to never use HCl,never use any chloride,including methyl chloride ,as uncontrollable rusting may be the result............if there is a coating of sealant,you will need the correct stripper to remove it properly,then you can repeat the sharp gravel shakeout.Its possible caustic soda will remove some sealants,but most need the correct stripper for the coating...............on the subject of cleaning.....have you taken note of the advice to clean out sludge traps in the cranks?

KenGriggs
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Re: Cleaning out fuel tank of Sq 4

Postby KenGriggs » Tue Feb 26, 2019 4:06 pm

https://www.tankcareproducts.co.uk/ I used their products on my Sq4 tank, which had previously been sealed with a product called Petseal, which wasn't compatible with the ethanol in modern fuels. They do a Petseal remover, and various de-rusters and chemical cleaners and de-waterers for use prior to using their sealant. It's quite a laborious process, but worth it, and it's worked for me. You need to get the large sealant tub for the square 4. I think it's called Sureseal Titanium. If you don't fancy tackling it yourself, they will do it for you.

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paul.jameson
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Re: Cleaning out fuel tank of Sq 4

Postby paul.jameson » Wed Feb 27, 2019 8:49 pm

I'm glad to hear that the fuel tank is clean.

A tad more important is the cleanliness of the crankshaft sludge traps. If these are not clean, your engine will self destruct, usually in under 500 miles. Spares are virtually impossible, due to the number of fools who have ignored warnings such as this.
Paul Jameson
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Former Machine Registrar & Archivist, General Secretary and Single Spares Organiser (over a 25 year period).
Now Archivist once more - but not Machine Registrar.

roger.fellows
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Re: Cleaning out fuel tank of Sq 4

Postby roger.fellows » Wed Feb 27, 2019 10:26 pm

I think this bike belonged to a club member of long standing and was well-used and maintained but if so it must be recognised by some????????

john.whiting
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Re: Cleaning out fuel tank of Sq 4

Postby john.whiting » Thu Feb 28, 2019 4:41 am

I would think any 4 without an oil filter would need a crank clean out...........the cranks are a centrifugal separator in operation,and it doesnt matter what kind of oil is used ,anything heavier than oil will lodge in the traps.

tomwalker
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Re: Cleaning out fuel tank of Sq 4

Postby tomwalker » Thu Mar 07, 2019 5:49 pm

Mike
I have used acetone to remove old tank sealant and old petrol gunge.
It wont touch rust, but you should be able to rinse the worst of that out.
It might be worth trying before the very comprehensive acid technique from RC.
Acetone is not as dangerous as acid, but will lift paint very effectively, so you need to keep it off the outside of the tank.
Tom Walker
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Re: Cleaning out fuel tank of Sq 4

Postby malcolm.johnson » Fri Mar 08, 2019 8:59 pm

My Square 4 had a liner that was gradually dissolving into the fuel and hence carburettor, as well as flaking off the inside of the tank. I removed my liner using MEK (methyl ethyl ketone) and the resultant pile of debris is pictured below.
6.  Removing old liner.JPG
The next phase included an acid rinse to clear the rust and finally after lots of cold water rinsing, a neutralising treatment using phosphoric acid. The end result is pictured looking into the filler and shows the panel that was taken out and welded back in after tank repairs (before my ownership). I think the liner was installed as a precaution by the restorers at the time. I never replaced the liner as it did not leak and now the carburettor does not gum up as it used to.
16.  Tank second clean  (1).JPG
Some time later I did a second MEK treatment and still some more came out from the blind side of the tank inner. As with all these jobs the chemicals can be dangerous to use, so take every precaution.
Attachments
16. Tank second clean (4).JPG


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