ETZ250 Petrol Tank (so near and now so far)

[nice2day]

Hi Chaps. Just when you think it's finished something always seems to go wrong and your weeks away from finishing. Yep. Today I refitted the carb (I think I have improved the tickover now) and thought I'd check if the petrol tap was tight. To my shock and horror it WAS leaking and had bubbled up a great big area of paint under the newly sprayed tank. I really couldn't say if had just started or had been leaking since I removed the petrol pipe a few days ago. I'm not absolutely sure but it seems the threaded tap stub might be the source of the leak so it will need re-braising and the tank completely stripped and resprayed

BUT>>>>Here is the problem...the tank was massively rusty inside (outside perfect) so I used TAPOX tank sealer. I am a great fan of this product and used it lots of times on different tanks with total long lasting success. Unfortunately what must have happened is that on tightening the tap I must have slightly rotated the stub within the tank as maybe the metal was extra thin due to corrosion. So now I have to get the leak fixed but what with the TAPOX inside, trying to use a hot flame isn't going to do this sealant any good. I was thinking that maybe TIG BRAISING might be possible? (thoughts on this?)

I also considered that to get a firmer stronger fixing it might be better to make up a new male threaded fitting in the shape of an inverted top hat so that the wide flange of the fitting (about 22-25mm in diam?) could be TIG welded to the bottom surface of the tank after the original stub had been removed. At least there is good metal surrounding the hole. This would avoid the original threaded tube (stub) simply twisting again when tightening the tap.
Any thoughts or personal stories on these tanks?...Much obliged for your ear as ever...All the best.

Les

[Puffs]

Removed

[breakwellmz]

BRAZED







BRAISED -

[AlanJ]

Hi Les,
What a bummer, sadly I don't know the setup you have for this petcock but what's bothering me is it's failed in the area due to previous corosion then, if you attach it as was, and it's leaking because there is a lot of leverage against that surface it will probably do it again. Is there any way you can large penny washer that area inside and out on the stub, then you could easy flo (silver solder) the outside washer to the tank or, you could epoxy it to the tank, but with the amount of leverage on that tap ( all my pets are hard to turn) I would bite the bullet and solder? If you had a threaded stub with a large washer welded to the top edge then into the tank and washer the outside with a nut to hold it you could then use epoxy or something similar. If any of that doesn't come over, give me a pm with your nr if you want to Les.
Stay safe Alan.

[Puffs]

Removed

[breakwellmz]

Hi Chaps. Just when you think it's finished something always seems to go wrong and your weeks away from finishing. Yep. Today I refitted the carb (I think I have improved the tickover now) and thought I'd check if the petrol tap was tight. To my shock and horror it WAS leaking and had bubbled up a great big area of paint under the newly sprayed tank. I really couldn't say if had just started or had been leaking since I removed the petrol pipe a few days ago. I'm not absolutely sure but it seems the threaded tap stub might be the source of the leak so it will need re-braising and the tank completely stripped and resprayed

BUT>>>>Here is the problem...the tank was massively rusty inside (outside perfect) so I used TAPOX tank sealer. I am a great fan of this product and used it lots of times on different tanks with total long lasting success. Unfortunately what must have happened is that on tightening the tap I must have slightly rotated the stub within the tank as maybe the metal was extra thin due to corrosion. So now I have to get the leak fixed but what with the TAPOX inside, trying to use a hot flame isn't going to do this sealant any good. I was thinking that maybe TIG BRAISING might be possible? (thoughts on this?)

I also considered that to get a firmer stronger fixing it might be better to make up a new male threaded fitting in the shape of an inverted top hat so that the wide flange of the fitting (about 22-25mm in diam?) could be TIG welded to the bottom surface of the tank after the original stub had been removed. At least there is good metal surrounding the hole. This would avoid the original threaded tube (stub) simply twisting again when tightening the tap.
Any thoughts or personal stories on these tanks?...Much obliged for your ear as ever...All the best.

Les

Save yourself a lot of time and effort (and possibly an Mot failure next time round) and look for a replacement tank, they can`t exactly be rare. From someone who can TIg weld, braze and Oxy-acetylene weld i wouldn`t attempt any of them on such a tank, sorry.

[breakwellmz]

Brazed or welded then; my life will be so much better knowing this, and now Les will know exactly what to do. Thanks breakwellmz!

On the topic, my fear is indeed too that corrosion is more widespread. Then more drastic measures may be required.

Brazed or braised. Glad to be of service.

[AlanJ]

Hi Les,
Sad to say, I think breakwellmz is right.
Alan.

[nice2day]

Thanks for ALL your replies....
Let me explain the paint problem first. The idiot car sprayer I took the tank too used water based base coat!...I did not realise he would be so stupid. He might have used 2K lacquer on top but I have a feeling even that might not be. As you can see my etch primer and filler primer has mostly resisted the petrol but the water based colour coat has sucked up the petrol better than a sponge and blistered up like a balloon and fell off. 2K is totally resistant to petrol which is what I expected him to know and use....I will be getting back to him and asking for a refund.

I think the advice to get another tank now becomes a necessity as I THINK I can see pin hole swellings coming up elsewhere.
Even though I used 2x layers of my trusted TAPOX it seems this has not been successful. I was silly really when I knew there were a few pin holes I should have soldered up the outside of the tank before progressing further or writing it off at that point.

As there is nothing to loose now I will attempt a fix by soldering with a micro blow torch. It might work but then I need to fill the tank with petrol and leave it for a leak test. I will try to source a better tank (see wanted section) . Only a couple of days ago there were 2x brand new unused tanks for sale on Ebay...unfortunately and stupidly it slipped my mind and I forgot to bid on them. Second hand wise, I reckon the "oil in tank bikes" will have the least rust in them. I have now prepared the area and stub for soldering with a silver doped low melting point solder (photo No2) which has the other advantage of being the strongest solder available....I have nothing to loose I reckon.....More to follow and thanks again.

Les

[Puffs]

Removed

[Blurredman]

Petrol is the best cleaner out there, also the cheapest- water is the reason for rust, whether in the fuel from the petrol station, or just seeping through the seal. But water is heavier than oil and petrol- Metal tanks aren't very thick so it doesn't take a lot of water a lot of time to do damage. It's likely that the previous owners maybe only went a few miles into reserve.

My 251 tank was and still is extremely rusty inside- to the point that for the first few thousand miles I was constantly fishing small rust particles from the reserve flow on the tap- as it was clogged up. But that was a few years ago. Constant use I think has allowed my tank not to rust too much more.

[nice2day]

Hi Puffs thanks for the tips and comments. At the moment I have successfully soldered the stub. You can't see from the photo but I got a beautiful fluid run around the joint and it fully wetted the area. I then built up an extra level of solder to form a strengthening fillet, which is not easy with this silver doped, very fluid solder. This might give the impression that my soldering is a cold brittle one but it is simply the puddling of the surplus solder around the edges but the solder is fused really well below the fillet. I will attempt a leak test tomorrow but I'm still worried regarding the pin holes...TBC....Les

[breakwellmz]

That looks to have taken well.
Shame you havn`t got an endoscope to check out what the inside looks like.
This wouldn`t fit would it? - https://www.facebook.com/marketplace/it ... =undefined

[nice2day]

Thanks. I must say it looks a little clunky at the edges but as said, it is fully bonded to the stub and tank. It shouldn't leak....ooops ...now it will!
If it does I'll do it again.
Thanks for the heads-up on the tank but that is the later tank (251) Here's the link to the one I let get away...I'm so annoyed as this would have been perfect instead of having to restore a used one: https://www.ebay.co.uk/itm/Genuine-Bran ... 3809397453
As regards looking inside the tank, you can see clearly the inside area around the stub by shining a small torch and looking at an angle. I was amazed that the TAPOX was still intact but just a slight change in colour (lighter)
The micro blow torch was perfect for the job as it produces a tiny needle sharp flame that heats up the metal really fast but didn't heat up too much of the surrounding metal. There are several variations of this type of this tool:
https://www.ebay.co.uk/itm/12ml-Butane- ... 0005.m1851
Les

[JawasandMZs]

That happened to me on gs500. After weeks of fruitless faffing with snake oil remedies I just put on a 2nd hand one. £60 & the pain was the old lockable filler cap was locked shut & had to be hacked off. Be glad it's only an mz.