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Fuel Tank Repair


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#1 gaspen

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Posted Yesterday, 06:17 AM

Hi

 

I cut the tank in two to clean as a thick "material" sticked hardly on the bottom. Now it's cleaned as good as possible

 

I have degreaser and Brunox. My idea to brush it with Brunox, weld it, and fill the welding seam with Brunox again.

 

Finally I'd fll it with POR-15 but I am not sure if Brunox is a good primer fro POR-15

 

Any advice ?

 

 

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#2 sonscar

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Posted Yesterday, 07:46 AM

Just my experience here POR paint over rust.I bought all there recommended steps and followed the instructions.Months later it peeled off in strips.Use two pack epoxy onto the bare metal.Others may have had better results.rough the surface with 80 grit,NOT a wire wheel.Steve..

#3 mbolt998

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Posted Yesterday, 07:50 AM

Nice job. I suspect that anything you put in there will melt, smoke, catch fire, and make horrible fumes and a mess when you weld it. Could you weld it first, block up the hole at the bottom, fill it up with something, and then drain it back out of the bottom? That way it would coat everything in there if it was sticky enough. But I don't know what you can put in there anyway that petrol won't wash off.



#4 Spider

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Posted Yesterday, 08:09 AM

POR15 likes lightly rusty or course blasted steels, no primer or anything else there.

For this job though, and again, similar preparation of the steel, they have a Fuel Tank Repair Kit, which would be much better suited. Clean the tank back to bare metal, weld it up, then use their kit which comes with a cleaner and pre-treatment. I suggest welding (or brazing) the tank back together as bare metal as i) it will weld (or braze) better and happier with clean metal and ii) you chosen tank liner will work MUCH better if there's no contamination from burn Brunox or anything else.

For what ever it's worth, I make a few special fuel tanks, which I line with either the POR15 Fuel Tank Kit or we have a local product, KBS, which is just as good.



#5 stuart bowes

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Posted Yesterday, 08:54 AM

so what do you do once it's welded back in one piece, pour in the POR and just turn it round and round to cover all the surfaces, pour out excess ? or is there some clever trick (just out of curiosity really)

also would it not have been better to pull the seam apart and re-weld that again, instead of now having to seam-weld all round the outside (again just curious if there's some reason) when they make it originally is that just spot welded and how do they get a good seal or is it a roller seam weld thing

Edited by stuart bowes, Yesterday, 08:59 AM.


#6 Ethel

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Posted Yesterday, 10:30 AM

Getting the seam apart would be hard work, but cutting just inside it should leave you with something that's easier to weld up and even easier to braze. I'd have been tempted to chuck some gravel in & tumble it, but have to admit the Gaspen's done an excellent job of cleaning it up that I doubt would have been matched.



#7 gaspen

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Posted Yesterday, 11:12 AM

so what do you do once it's welded back in one piece, pour in the POR and just turn it round and round to cover all the surfaces, pour out excess ? or is there some clever trick (just out of curiosity really)

also would it not have been better to pull the seam apart and re-weld that again, instead of now having to seam-weld all round the outside (again just curious if there's some reason) when they make it originally is that just spot welded and how do they get a good seal or is it a roller seam weld thing

 

Originally it was welded with a "roller-welder", that's why it does not leak. I haven't got the equipment to cut and re-weld that seam. 

 

POR-15 kit has a degreaser and a surface conditioner, I guess it has some acid to "bite" the surface and the final layer will adhere better to that surface.

 

If the surface is prepared you just fill the final sealer into the tank and rotate it every direction to reach every "corner"

 

It looks like Brunox is a different story.



#8 stuart bowes

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Posted Yesterday, 11:22 AM

gotta be honest looking at yours now I do want to cut mine open and clean it properly lol

 

I won't though, it's pretty clean (looking with a torch) and with my limited skills it'll be more risk of leaking (and looking wonky or something)

 

how did you cut it open anyway, and did you flush it first or steam it or anything


Edited by stuart bowes, Yesterday, 11:23 AM.


#9 sonscar

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Posted Yesterday, 12:27 PM

My tr7 tank suffered badly from rust.I used a tank sealer kit ethanol proof from a UK firm Rustbusters.Twelve years later it is still good.No cutting open was involved.It was reasonably expensive and if a tr7 tank cost the same as a mini tank I would have bought new.Just my experience.Steve..

#10 nicklouse

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Posted Yesterday, 12:30 PM

Some reading and products 

https://www.frost.co...TxoCLJIQAvD_BwE

 

ps Brunox and petrol. Not sure. I seem to remember using petrol to clean it up.


Edited by nicklouse, Yesterday, 12:32 PM.


#11 weef

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Posted Yesterday, 12:41 PM

Thats a good job cleaning up the tank ready to weld together.

I don't know what method you are going to use to weld it back together, TIG, MIG or OXY /ACC,  TiIG would be best if you have it.

In any case getting to the practicalities of welding it, on the half without the origonal seam I would plug weld a strip, maybe 30mm wide and 1.5mm thick, right round the inside of the cut to form a lip that can be pushed into the other half, just like a tin lid, this will accurately locate the two halves and allow you to leave a small gap between the edges to ensure complete penetration. when welding. 

The lip will locate the two edges together and prevents them from moving / distorting when welding.



#12 Spider

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Posted Yesterday, 05:55 PM

To be honest here, I feel cutting a tank apart to clean it makes for a lot more work.

If the tank is sound enough, but has some rust on the inside, there's a whole host of chemicals available these days that can be used to clean them up, or another popular method is if you can get a hold of a cement mixer, wire the tank to that, so you can tumble the tank, fit an old sender, put 2 handful of 5 and 10 mm gravel in it, an old cap on, and let it run for about 2 - 3 minutes, have a look inside to see how it's cleaning up, usually within 10 minutes it'll be done.

I'd also suggest removing the gauze filter that's in the tank. If you want a 'filter' here, fit an external one, at least then it'll be serviceable.

Then clean it out, fresh water will be OK, use a POR15 Kit and follow the instructions to the letter, even here, the cement mixer is handy as you need to tumble the tank over and over and over,,,, The tanks I do are usually new and clean of rust, so I use an engine stand to tumble the tanks for the POR15 process. One thing I'll add here is don't under estimate the time this will all take.

 

The Tank halves are resistance welded together originally. Any rust that resides in the seem here, the preparation chemicals in these fuel tank repair kits will deal with that. I find with the POR15 Kits, they have available one that's size to do motorcycle fuel tanks, that's fine to do one Mini (or Moke) fuel tank. If you follow the instructions, you'll get 20+ years from the tank, as long as the outside is in good order.

 

Don't forget to blow out the breather and fuel take off pipes as the last part of this process !



#13 gaspen

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Posted Yesterday, 05:57 PM

This crap was sticked on the bottom. It was 2-3 cm thick and dense. It would take ages to remove it without cut the tank.

 

Also the bracket of the pipe gone but I've spotted an other one. I discarded the blocked filter also.

 

Anyway I will buy a POR15 kit and take a try

 

Thanks

 

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#14 gaspen

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Posted Yesterday, 06:41 PM

Thats a good job cleaning up the tank ready to weld together.

I don't know what method you are going to use to weld it back together, TIG, MIG or OXY /ACC,  TiIG would be best if you have it.

In any case getting to the practicalities of welding it, on the half without the origonal seam I would plug weld a strip, maybe 30mm wide and 1.5mm thick, right round the inside of the cut to form a lip that can be pushed into the other half, just like a tin lid, this will accurately locate the two halves and allow you to leave a small gap between the edges to ensure complete penetration. when welding. 

The lip will locate the two edges together and prevents them from moving / distorting when welding.

 

I don't know how dense the sealer is but I'm afraid that it won't flow under the strip






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