K75C Tank Help/Advice

[ledoux]

Need some help from all you experienced techs/builders. I got hosed on a deal for a 17k mile 1989 K75C I discovered tonight when I began to prep the tank for pinhole leak repair and discovered 3 holes hidden with bondo and smart paint matching.

Can the pictured hole be repaired? The other 2 I think will be fine with some JB Weld. The pictured hole is past the seam on the lower left side of the the tank.

I'm glad I found this before the bondo failed on the highway but dude took me for a ride and my $2500. Plead help me reclaim some of my pride at least.

[MonkeyMcBean]

I found this at Napa and carry it with me on long trips just in case. It should work. It says "for permanent repairs" in the instructions.

[Chaos]

I've had the jb weld patch leak after a couple years.  The permatex patch has been good the last 5 years. Clean up the area good and put a big patch over the mess, you should be fine.

[ledoux]

Thank you Monkey & Chaos! This forum is great bc of members like you willing to help.

My next question would be of how to apply it. Would it be best to apply externally or internally to the tank? If applied internally, would you tape/block the external side or just sand it down after it cures?

[MonkeyMcBean]

I've never done it, but I'd probably push from inside until it smooshes out. Then I'd form the outside a bit. Let it cure and then sand/file to the shape I want.

I've never used the product though.  So assume everything I say is wrong.

[ledoux]

Can't make it any worse. Some one at work recommended a shop in MN that does tank work. If it doesn't work I'll send it there. Thanks MonkeyMcBean.

[wmax351]

I'd try either the JB Weld stick or a dedicated tank repair goo. Push from the inside, and flatten on the outside. Let that dry, then put a bit more on the outside.

Worst comes to worst, a used tank is cheap on ebay or CL.

[frodef]

I did my tank with some of those aluminum brazing rods off ebay. Took a bit of practice but seems it worked well (except I scorched the paint around it too much). My hole was a bit smaller though.

[dansvan]

use the tank repair epoxy. JBWeld will leak eventually as others have said. Apply from either side and flatten out both sides.

[thegingerbeardman]

as with any adhesive, prep is the key to success

if you can get your hands inside the tank to thoroughly clean the metal (scotchbrite or similar, wipe with acetone after to remove oil) absolutely do it from the inside

and then do a little more from the outside.

[Liverpool Brick]

I have a similar sized hole in exactly the same place in my tank. JB weld lasted 4 years, Permatex lasted less than a year. Worse still, the Permatex putty you put in the hole before applying the gauze had disintegrated into grot and was lying in the tank. I've taken the tank off today and stripped it and I'm hoping to get it aluminium welded as a permanent repair.

[kenray]

I read someone used a aluminum epoxy type subtance. Apparently it comes in a tube, you pinch off what you need, and work it in your hands to activate it. Then apply it to the hole, sand as needed. User beware as I have never tried it.  I think there may be several variations of the stuff. I believe you have to be sure and get the type made for aluminum. Kenray in Katy Tx.

[stryder]

So, I'm a little miffed. They're aluminum tanks. What causes holes in them?

I didn't think this would ever be an issue.

Thanks.

[Chaos]

Aluminum does not rust but it corrodes.  That spot is where water settles.  Good idea to add a can of gas treatment that absorbs water every once in a while.

[stryder]

Aluminum does not rust but it corrodes.  That spot is where water settles.  Good idea to add a can of gas treatment that absorbs water every once in a while.

Any recommendations?

[jay1622]

I'm a huge fan of Sea Foam. I use it in damn near everything. Read up on it; it's been around for a while, but has really taken off in the past few years. There's plenty others, but this gets my vote.


http://seafoamsales.com/sea-foam-motor-treatment/

[The Mighty Gryphon]

I've used Seafoam in the past.  It's a great system cleaner, but a bit expensive for just soaking up water. 

I would recommend getting a good drygas additive.  Check the label.  The ones with isopropyl alcohol are the best as the ones that use ethanol or methanol are more corrosive and harder on the fuel system.

[F14CRAZY]

I run Starbrite Startron once in a while. It's a marine gas additive which would take care of moisture.

Considering I run my gas tank pretty low (4+ gallons until full again) and refilling, and doing this a few times a week, do I have to worry about holes from internal corrosion? I would think that any moisture that gets in there would be burned-out.

With how hot K's get in warm weather, and boiling gas in the tank, wouldn't moisture get boiled off?

[MonkeyMcBean]

Gas boils at a much lower temp than water. The water does not boil when the gas does. Have you ever felt like the tank was 100 degrees? (212F).?? Really hot.

[HuckItForward]

I had a pretty gunked up tank when I bought mine and was looking at tanks on ebay.  Many can be found in good condition for under $100, which is less than you'd have to pay a shop.  Might be worth trying the permatex and if it fails, you can always get a used tank online.  Sorry to hear about the swindle.

[The Mighty Gryphon]

Water that separates out settles to the lowest point of the tank.  You would have to run the tank totally dry to remove the water that has separated out.  And as soon as you sucked it up it would shut down the engine.  This is how the water stays in the tank long enough to do damage.

You need to use a drygas to absorb the moisture and dissolve it in the fuel at a low enough concentration to allow the engine to keep running.

[stryder]

So I bought some K100 fuel additive, that's supposed to stabalise fuel for up to 2 years, and, get this, "burn water".  :laughing-on-ground:

The parts department dude tells me it, get this, turns water into alcohol.  :mbird Hmmm, where have I heard stories of water being turned into alcohol before...oh yeah..now I remember.  :yes

In any case, I've been a snake oil sucker all my motoring life so I buy me a large bottle of the stuff and immediately put some in my tank. Don't ask how much, but it was a nice little pour. It's supposed to be like 1:150 or something like that, so a nice little pour sounded about right.  :2thumbup:

I get home and immediately pour some in my other bike, which is almost in storage, and run the engine for a bit. I then go on the interwebs and look the stuff up, and came across this page that shows the K100 stuff being "tested" with a couple of other popular fuel additives in a way I thought was pretty neat: 4 small jars, 3 with fuel additives, one without, equal amounts of gas and water in each jar, with a steel screw placed inside, and then let sit for 1.5 years.  The jar with the K100 shows the water and fuel have not separated, and the screw has not rusted. The other three screws didn't fare as well and the water and fuel separated.

I'm not flogging this stuff as I just bought it for the first time, but do feel that test could be seen as pretty relevant to corroding surfaces inside a fuel tank, and effective water "containment".  :riding:

http://ttrno.com/blogs/news/4761782-ethanol-vs-fuel-treatments-k100-success-story