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1Back to top Go down   How to repair a leaking fuel tank? Empty How to repair a leaking fuel tank? Wed Jul 15, 2009 5:13 pm

Guest

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Hi all,

My 1984 K100 has been up and running for a month or more now - after finally getting it registered in the UK. It's running well, but there is a small leak from the fuel tank (front bottom left-hand side before the lower seam).

This is a leak that had been repaired before.

Should I repair this from inside or out?

What is the best method/material for the job?

Will post some pics - there's an odd fairing on my bike! Wonder if anyone else has one.

Best,
Neal

    

downssm

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Hey Neal, Hi!

My 88 was repaired with JB weld on both sides when I bought it. It looked to have been on there a long time, since it had been painted over. I replaced my tank but who know how long it would have lasted... A good welder can fix it easily with a TIG machine also, once it's cleaned out. I don't know about sealing the inside. Maybe someone else can say how that works.

Luck!
Steve

    

K-BIKE

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Hi Neal,
There are two ways to fix this, internally and externally. The internal fix uses a resin which coats the whole tank interior and works really well. My pal's Suzuki Intruder tank rusted out and had a big hole. A patch was fitted and brazed in and the tank treated and is now perfect again plus protected from further problems. My K bike tank had a small spot where it was getting damp with petrol and I used Permatex kneadable petrol tank sealer. I took the tank off, cleaned the area and with the tank positioned so there was no pressure pressed a blob into place firmly. It sets very hard and has not leaked at all since. I know several people who have used that and a similar Loctite product.
Regards,
K-BIKE

    

Guest

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Great thank you!
Neal

    

the mule

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Hi neal

Just discovered I had a 3mm hole in the tank immediately underneath where the fuel pump sits just inside the seam. After reading this thread and others on flyingbrick website and general google search on various products available went with the Permatex GTR 1 Gas Tank and Radiator Repair kit. $8. Only used 10mm piece off the roll. They claim it sets hard within 5 minutes and can be drilled machined etc in 2 hrs is pretty accurate too as it set hard as a rock. The Full cure time indicated is 24hrs and unlike some of the other products claimed suitable it is impervious to fuel deisel oils detergents etc. not merely resistant.

https://s5.photobucket.com/albums/y156/the_mule/
    

6Back to top Go down   How to repair a leaking fuel tank? Empty fuel tank leakage Fri Jan 10, 2020 7:25 am

chris.edwards2

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I'm in the UK. I've repaired my  fuel K100 tank with putty twice. First time lasted 5 years. Second time 5 months. Second time I cleaned the area scrupulously. I used Granville repair putty. I have been told that the latest petrol additives in the UK are much more reactive and aggressive. I know this as my fibreglass tank on my old BSA became very porous a few back after 40 years of ownership! So does anyone know of a putty that will work for a decent time with current petrol? (None of the ads seem to mention this)

    

mike d

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The following has been around for years (notsuitabel for plastic or fibreglass tanks though)

https://www.amazon.co.uk/Por-15-Sealer-Repair-prevention-236ml/dp/B00APFN1YM

Supposed to be o.k. for use with high ethanol fuel.

Mike

    

brickrider2

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1996 K1100LT
    

9Back to top Go down   How to repair a leaking fuel tank? Empty fuel tank leakage Fri Jan 10, 2020 2:02 pm

chris.edwards2

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Thank you both. I hadn't thought of the low temp brazing option, although have come across it years back. Never done it tho'~. I'll strip the tank down and decide when its bare, cheers

    

10Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Fri Jan 10, 2020 2:50 pm

moriarti

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Hi Neal You don't say if the tank is Alloy or steel but i would think Allo on this year.low temp Alloy welding/brazing is a first class repair. For safety rig up a steam feed to the inside of the tank to prevent igniting of fumes,simple is best ie kettle with rubber tubing works well. Smile Smile
N/B good videos on utube

Just remembered Liquid Metal developed for the military impervious to petrol etc no heat required flows well wort a try



Last edited by moriarti on Fri Jan 10, 2020 3:52 pm; edited 1 time in total (Reason for editing : brain in slo/mo)


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1984 k100 rs red/black VIN  0004449
    

11Back to top Go down   How to repair a leaking fuel tank? Empty last try with putty Tue May 05, 2020 3:02 pm

chris.edwards2

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thanks for all ideas but I needed to use my bike so tried a last attempt fix with a putty. I used PC7 - it took 3 days to cure and I read somewhere that slower cure meant more inert epoxy.. (maybe rubbish). Only 4 months but no leak yet... time will tell

    

12Back to top Go down   How to repair a leaking fuel tank? Empty alloy Tue May 05, 2020 3:03 pm

chris.edwards2

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ps -tank is alloy

    

13Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Mon Aug 02, 2021 10:31 am

Beamer

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@downssm wrote:Hey Neal, Hi!

  My 88 was repaired with JB weld on both sides when I bought it. It looked to have been on there a long time, since it had been painted over. I replaced my tank but who know how long it would have lasted... A good welder can fix it easily with a TIG machine also, once it's cleaned out.  I don't know about sealing the inside. Maybe someone else can say how that works.

 Luck!
  Steve

I'd be doubtful that welding would be successful on a rotted through tank since the metal is very likely thin and weak in the surrounding area. It's a bit like welding a rusty exhaust pipe. If you can add a patch to some sound material a bit further it can work but filling will just melt more holes.

Also ali has high thermal retraction on cooling so the repair pulls in and is never clean. You could get away with welding inside the line of the seam where it would be less visible but it's tricky on ali tanks. 

I have K100 tank which has corroded through in several places due to water infiltration resting in the bottom of the tank. I have to assume that the well on both sides is pretty thin and  weak in multiple places. I will try to find a fluid resin suggested here by some.

The challenge is how to clean the inaccessible metal inside the tank. First port of call is jet cleaner but I'd like some abrasive solution to remove any oxide and have clean sound metal. At the same time I don't want any kind of sand or carborumdum dust hanging around. Well may be course gained quartz sand ... ?

The trouble is these tanks really don't drain well because of the deep ring for the filler cap.

Any ideas on chemically reducing the oxide layer with an acid rinse before applying these products?

Any tricks to share?

    

14Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Mon Aug 02, 2021 12:36 pm

Jibe

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Mine went I had it tig welded but it was unsuccessful, I ended up using chemical Metal epoxy

    

15Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Mon Aug 02, 2021 1:26 pm

Laitch

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@Beamer wrote: The trouble is these tanks really don't drain well because of the deep ring for the filler cap.
Would you please explain how a ring for the filler cap affects drainage of the tank? How much fuel is left over after emptying that couldn't be sopped up with an old sock?


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1995 K75 81,000 miles
How to repair a leaking fuel tank? Usa-lo10
    

16Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Mon Aug 02, 2021 1:34 pm

Beamer

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@Laitch wrote:
@Beamer wrote: The trouble is these tanks really don't drain well because of the deep ring for the filler cap.
Would you please explain how a ring for the filler cap affects drainage of the tank? How much fuel is left over after emptying that couldn't be sopped up with an old sock?

I was not discussing removing fuel.

    

17Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Mon Aug 02, 2021 1:49 pm

Laitch

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@Beamer wrote:I was not discussing removing fuel.
I enjoy a cryptic answer as much as the next person. Smile

I didn't read that you were discussing drainage until the post to which I responded. That's why I asked. Drainage and filler cap were in the same sentence. Previously, you seemed to be discussing fuel separation leading to water residing along the lower seams of the tank. How does the filler cap opening contribute to all this.


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1995 K75 81,000 miles
How to repair a leaking fuel tank? Usa-lo10
    

18Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Mon Aug 02, 2021 2:30 pm

Beamer

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me wrote:The challenge is how to clean the inaccessible metal inside the tank. First port of call is jet cleaner but I'd like some abrasive solution to remove any oxide and have clean sound metal. At the same time I don't want any kind of sand or carborumdum dust hanging around. Well may be course gained quartz sand ... ?

The trouble is these tanks really don't drain well because of the deep ring for the filler cap.

It was in the post you replied to, on the previous line!  If you don't read what is there, I can understand you finding it "cryptic". Just don't blame me or get snarky.

    

19Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Mon Aug 02, 2021 7:56 pm

Laitch

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@Beamer wrote: If you don't read what is there, I can understand you finding it "cryptic". Just don't blame me or get snarky.
Are you trying to corner the market on snarkiness, or keep up the pace, Beamer?   Laughing  Regardless, my interpreter tells me you might be referring to removing the filings, so I'll go with that.


__________________________________________________
1995 K75 81,000 miles
How to repair a leaking fuel tank? Usa-lo10
    

20Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Tue Aug 03, 2021 2:48 am

Beamer

Beamer
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Fine, so now we've established that the deep ring supporting the sunken filler cap impedes cleaning of the fuel tank, hopefully we can get this thread back on the subject of repairing leaks.

    

21Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Tue Aug 03, 2021 10:18 am

moriarti

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White Vinegar strong enough to remove reside without risk of damage.You can make several Thingamagigs to scrub about with.  Iwould look at repairing the tank Inside and Outside, Belt and braces moto Very Happy


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1984 k100 rs red/black VIN  0004449
    

22Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Tue Aug 03, 2021 10:32 am

Laitch

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@Beamer wrote:. . . we've established that the deep ring supporting the sunken filler cap impedes cleaning of the fuel tank . . .
You really should take sole credit for establishing that.  Smile

I agree with Moriarti. Also, the tank bodies seem thin enough that abrasion of them could become problematic. Once tanks have been cleaned,  POR-15  has been used successfully by several Brick owners.


__________________________________________________
1995 K75 81,000 miles
How to repair a leaking fuel tank? Usa-lo10
    

23Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Tue Aug 03, 2021 10:57 am

Beamer

Beamer
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@moriarti wrote:White Vinegar strong enough to remove reside without risk of damage.You can make several Thingamagigs to scrub about with.  Iwould look at repairing the tank Inside and Outside, Belt and braces moto Very Happy

I was wondering about some kind of mild acid wash to remove the oxide layer but that needs to be based on science, it could end up worse. Abrasion seems better but with all the baffles, tubes and other structures inside these tanks, I don't see that being very practicable for much of the area.

    

24Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Tue Aug 03, 2021 1:06 pm

moriarti

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Mild acid wash!! That's vinegar. Should you require a scientific 100% guarantee, Send the tank to Professional tank repairer  company. study


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1984 k100 rs red/black VIN  0004449
    

25Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Tue Aug 03, 2021 1:15 pm

Beamer

Beamer
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@moriarti wrote:Mild acid wash!! That's vinegar. Should you require a scientific 100% guarantee, Send the tank to Professional tank repairer  company. study
Yes, thanks, I am aware that vinegar is A weak acid. That does not mean it is the best choice or suitable for aluminium or even that acid is the best option.

If I could rely on anyone who called himself "professional" to deliver 100% guarantees, I would not need to fix my own bikes and would not be wasting my time on forums. 

Seems like I subscribed to the smart reply thread by accident.

    

26Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Tue Aug 03, 2021 1:46 pm

Point-Seven-five

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Vinegar does a good job of gently cleaning the inside of fuel tanks. I have successfully used vinegar in three tanks to clean them out. There are at least 30 tanks that have been cleaned with white vinegar and documented on this and the Motobrick forums. A search will reveal a number of them.

Please know I am not being snarky with this post, just politely offering some of my experience.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

27Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Tue Aug 03, 2021 2:16 pm

Beamer

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many thanks .75 , that's useful. 

I think the question is what are we trying to remove?  General gunk and stale petrol vinegar is probable a good solution.

The thing here it for the corrosion there will be fluffy white aluminium oxide. For the resin to bond well I think that probably needs either etching way chemically or a bit of ( gentle ) mechanical abrasion to stick to clean metal.

I get the gut feeling swilling course quartz sand back and forth with water would be sufficiently abrasive, if I could clean it out well enough afterwards.

Maybe a water capable vacuum cleaner would suck it out to get around problem with the rim.

Moriati's suggestion of sealing both in and out side sounds a wise precaution, at least inside the folded rim.

    

28Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Tue Aug 03, 2021 2:32 pm

moriarti

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Easy Beamer, nobody's time is wasted on our forum, we ask and reply as best we can,sometimes with tong  in cheek humour, Maintaining/repairing our bikes is a way of life and if we can help each other that's a bonus  I F YOUR TANK IS A EARLY ONE WITH SINGLE BOLT MOUNT. Then i have a spare without any damage/repairs /leaks.If this of use PM me for price and shipping costs. Very Happy Very Happy  Happy to help.


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1984 k100 rs red/black VIN  0004449
    

29Back to top Go down   How to repair a leaking fuel tank? Empty Re: How to repair a leaking fuel tank? Tue Aug 03, 2021 4:38 pm

Beamer

Beamer
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Many thanks for that offer.  I'll chew it over. I'm getting more inclined to giving this one the bullet. It's probably more cost/trouble than it's worth to end up with a damaged/repaired tank. 
If I was a bit nearer, I'd snap it up.

    

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