BMW K bikes (Bricks)

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1Back to top Go down   Tank pinhole leaks Empty Tank pinhole leaks Mon Sep 23, 2019 10:44 pm

futech

futech
active member
active member
So I’ve recently noticed a few pinhole leaks along around the weld seam. I’m eventually going to get the tank repainted so I’ll most likely have them weld up the pinholes at the same time. In the mean time, does anyone have any recommended temporary fixes? I’ve seen a few fixes (por-15, permatex, jb weld) on early posts from a few years ago but wanted to see if anyone knows of any good up to date solutions.Tank pinhole leaks C9020d10
Tank pinhole leaks B7345610

    

2Back to top Go down   Tank pinhole leaks Empty Re: Tank pinhole leaks Tue Sep 24, 2019 1:16 am

RicK G

RicK G
admin
admin
Best thing is to weld them but before strip the paint right off as that will often show up some more and sometimes you just have to chuck them in the bin.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

3Back to top Go down   Tank pinhole leaks Empty Re: Tank pinhole leaks Fri Sep 27, 2019 3:54 am

jbt

jbt
Gold member
Gold member
I had my tank repaired with Pattex 2-components epoxy repair paste . Very easy to use, very effective, yet it was not obvious as the leak was at the basis of the mounting plug, at the bottom of its will, under the tank. The bike had fallen and the plug was forced inside, creating a crack.
It was supposed to be an emergency repair, made at 3000m. high on a moutain track in the Alps to stop pouring fuel, but one year after, not a single drop of fuel has leaked from there.
The age of these tanks may create problems when welding them...the alloy loses its consistency, turning into flakes.

    

4Back to top Go down   Tank pinhole leaks Empty Re: Tank pinhole leaks Sat Sep 28, 2019 12:29 am

DadofHedgehog

DadofHedgehog
Silver member
Silver member
@futech wrote:So I’ve recently noticed a few pinhole leaks along around the weld seam. I’m eventually going to get the tank repainted so I’ll most likely have them weld up the pinholes at the same time. In the mean time, does anyone have any recommended temporary fixes? I’ve seen a few fixes (por-15, permatex, jb weld) on early posts from a few years ago...

Back in the 1980s when I rode my trusty R100CS all around the country, BMW and Harley bikes came OEM with the insides of their steel gas tanks painted to prevent rust from the inevitable H2O condensation inside the tank.

Understanding that the K bike tanks are aluminum, and thus rust-free, I wonder with my 24-year old K75 about the (in)advisability of painting the inside of its much, much more complex tank interior. Why do it: because a layer of appropriate gasoline-proof coating could prevent age-related tank pinholing described here. What could be problematic: the complexity of trying to get a coating to seal and adhere to all the inside shapes and pieces of a K bike's aluminum tank, without messing up the submerged fuel pump & pressurized gasoline supply system.

At the least, perhaps coating the inside bottom 1/4th of the tank would yield nearly all the benefits with fewer problems.

Since our aluminum tanks are long out of manufacture and are now a classic finite resource, I'm curious if anyone here has tried, or heard of such an attempt at inside-coating these tanks. Comments?


__________________________________________________
PRESENT:
1995 K75T.  I am the 3d owner.  Bought it in June 2019 with 6,242 miles on the odo.
1991 K100RS 4-valve attached to a 1990 Flexit sidecar. I am at least the 3d owner. Bought with 21,00+ miles on bike's odo.

PAST:
old (indeterminate age) Ural + sidecar
1997 Buell S3T Thunderbolt
1982 BMW R100CS
1974 Kawasaki KZ400
1970 Suzuki Titan
    

5Back to top Go down   Tank pinhole leaks Empty Re: Tank pinhole leaks Sat Sep 28, 2019 4:14 am

MartinW

MartinW
Life time member
Life time member
The reason the tanks corrode is due to running ethanol laced fuels. A bacteria forms in the ethanol water mix in the lower recesses of your fuel tank. The bacteria then secretes acid which proceeds to eat away at your tank. It will also degrade your fuel pump damper and hoses. A mate had problems with all four of his bricks tanks and pump dampers. One tank had been sealed with a coating which was yellow brown in colour, brand unknown. The coating started to flake off in small pieces and chunks. 

There are apparently good coatings out there but you need to do research. I have never ever run ethanol and have not experienced any problems. When I first got my brick about 20 years ago I was told to replace the pump damper. I replaced it even though it was fine, it has now resided as an unused spare for the last 20 years.
Regards Martin.


__________________________________________________
K75s Hybrid
    

6Back to top Go down   Tank pinhole leaks Empty Re: Tank pinhole leaks Sat Sep 28, 2019 12:59 pm

brickrider2

brickrider2
Life time member
Life time member
In my area, I'm happy to see that more and more sources of "pure gasoline" are available.  However, in years past (7 +/-?) I coated my Laverda fuel tank with the product Caswell sells.  It's been subjected to a fair amount of ethanol fuel over the intervening years but the coating remains intact.  Good product to consider if you decide to coat a fuel tank.


__________________________________________________
1996 K1100LT
    

7Back to top Go down   Tank pinhole leaks Empty Re: Tank pinhole leaks Sat Sep 28, 2019 8:26 pm

RicK G

RicK G
admin
admin
@jbt wrote:The age of these tanks may create problems when welding them...the alloy loses its consistency, turning into flakes.
When this happens a higher frequency of the TIG is needed, wont always solve the problem but usually does.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

8Back to top Go down   Tank pinhole leaks Empty Re: Tank pinhole leaks Sat Sep 28, 2019 10:17 pm

DadofHedgehog

DadofHedgehog
Silver member
Silver member
@brickrider2 wrote:...in years past (7 +/-?) I coated my Laverda fuel tank with the product Caswell sells.  It's been subjected to a fair amount of ethanol fuel over the intervening years but the coating remains intact.  Good product to consider if you decide to coat a fuel tank.


Uuuuu! Nice. Thanks.


__________________________________________________
PRESENT:
1995 K75T.  I am the 3d owner.  Bought it in June 2019 with 6,242 miles on the odo.
1991 K100RS 4-valve attached to a 1990 Flexit sidecar. I am at least the 3d owner. Bought with 21,00+ miles on bike's odo.

PAST:
old (indeterminate age) Ural + sidecar
1997 Buell S3T Thunderbolt
1982 BMW R100CS
1974 Kawasaki KZ400
1970 Suzuki Titan
    

9Back to top Go down   Tank pinhole leaks Empty Re: Tank pinhole leaks Sat Sep 28, 2019 10:46 pm

DadofHedgehog

DadofHedgehog
Silver member
Silver member
@DadofHedgehog wrote:
@brickrider2 wrote:...in years past (7 +/-?) I coated my Laverda fuel tank with the product Caswell sells.  It's been subjected to a fair amount of ethanol fuel over the intervening years but the coating remains intact.  Good product to consider if you decide to coat a fuel tank.


Uuuuu! Nice. Thanks.

...and now having read up on the Caswell Gas Tank Sealer and watched a YouTube or two on the application, I guess I know what my Winter motorcycle project will be haha. Thanks BrickRider2!


__________________________________________________
PRESENT:
1995 K75T.  I am the 3d owner.  Bought it in June 2019 with 6,242 miles on the odo.
1991 K100RS 4-valve attached to a 1990 Flexit sidecar. I am at least the 3d owner. Bought with 21,00+ miles on bike's odo.

PAST:
old (indeterminate age) Ural + sidecar
1997 Buell S3T Thunderbolt
1982 BMW R100CS
1974 Kawasaki KZ400
1970 Suzuki Titan
    

10Back to top Go down   Tank pinhole leaks Empty Re: Tank pinhole leaks Sun Sep 29, 2019 6:16 pm

Matthew-Brisbane

Matthew-Brisbane
Life time member
Life time member
Had mine welded  and pressure tested  

Under test they found a couple of more pin holes 

Ended up having  8 holes welded up no leaks now 

Tank pinhole leaks 723598


__________________________________________________
1986 K100 RS Motorsport
#### K100 RS Project 
2011 R1200 GS
    

11Back to top Go down   Tank pinhole leaks Empty Re: Tank pinhole leaks Sat Oct 26, 2019 9:12 pm

futech

futech
active member
active member
Thankfully I was able to find a radiator place who was able to weld up everything. I was a little worried that the pitted area was a no-go. For now I’m holding off on a sealer, but I did end up doing the metal prep step to clean it up a bit.

    

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