Hi guys!
My lawn mower gas tank had a hole in it and I had to repair it because I could not find another one to replace it.
Later I had an issue where my Radiator reservoir busted a hole in it and so I used the same method to fix it as well.
The result is a permanent repair consisting of welding plastics together correctly for a permanent molecular bond that
is not glued or cemented together to fail later. Do NOT use a soldering iron or anyting that will scorch or burn the plastic.
... If you see smoke or smell melting plastic, you are doing something wrong and the material is getting way too hot.
I thought to myself, Maybe I should post this in case someone needs to know how to do this.. This might be old news
to most of you gear heads out there, but maybe it can help someone... I will put some pictures of my repair on the gas
tank for you to look at.. You can do the same with the radiator overflow or the washer fluid reservoir too or any plastic
container on a lawnmower or other car or stuff...
Read this all the way through and the notes at the end so you know the process and understand it before jumping in.
This is really simple and easy to accomplish.
check it out:
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First, here is a list of the tools you will need... nothing real elaborate or complicated..
You will need some plastic of the same kind to repair the break you find in your thing that you are repairing.
For this "slimy" kind of plastic like the radiator overflow bottle, the materials you need could be a plastic milk
container, or an alcohol container like I used here which is the same kind of plastic material (I used the alcohol
bottle simply because the bottle was similar shape to my gas tank). Do not use thick layers if possible to repair,
but instead lay down thin layers of patch until you feel secure that it is thick enough.. If you need it thicker, lay down
thin layers to build its thickness up one at a time.
Here is the damage I am repairing on my gas tank... It had some kind of plastic repair goop on it where someone
tried to plug the hole with some kind of plastic repair stuff.. Do not use this stuff because it is not a molecular bond
and will leak sooner or later. Welding it makes the plastic into one piece of plastic in the end.
I cleaned the tank outside very clean with some acetone and the alcohol in the bottle so I would have a squeaky
clean surface to bond to. I cut the bottle to match the contour of my hole I was patching... If you can see, I make the
patch about 1 inch bigger than the hole. This is to have bonding area all around the breach so the hole is thoroughly
covered, and the patch has leverage over the hole area since I can not weld on the inside.
Here is a picture of the piece cut out in front of my repaired tank so you see what it looks like and how it will look when finished.
It is bigger than the hole so the bond will be sure to reach all around the hole. If your issue is a crack or fracture, you might just
be able to tack the materials on both sides together without a patch, but I suggest using it to give a backbone to the parts being
joined.
I placed the cutout formed piece over the hole in the tank like this.. I am holding it in place to see how it will fit and how much work
I will need to do to make it fit best.. I will apply only one layer because I feel it is strong enough and will patch very well.
Here is the steps to weld it on:
* Warm a wide area around the tank surrounding the hole with the heat gun until it feels and looks "tacky" and a little "gooey", but do not "melt" it.
* Keep the tank at that temperature by moving the gun away from it a little and put the patch in the heat path to make it start to be 'tacky" too.
* Drop the patch onto the tank exactly how you planned it out before and apply heat back to the patch on top of the tank.
-- they should both be "tacky" at this point and will adhere readily.
The plastic patch and tank are now bonded to each other, but you will need to "knead" them together a screwdriver or putty knife to apply some
pressure in case any air bubbles or liquid is trapped between the two plastics to keep them from bonding. Be careful though because the hot plastic
is easy to distort until it cools off again.
The result will look similar to this:
You can take more time and dress it up to look better, but in my case, the gas tank is under some framework, so I was just
happy it was fixed finally. You can see where my dirty fingers got the plastic dirty as well touching on it inadvertently.
When you finish patching the hole, the plastic will be "tacky" for quite some time until the plastic cools off...
!!! Let it cool off by itself and do not try to hurry it along or you could crack the new welds !!!
I pressurized the tank withe all the holes plugged using compressed air to be sure I had a good bond all around.
Here I filled it with water to sit over a weekend to come back and see it it seeped out any or did not bond..
It was a perfect patch job and the repair is stonger than the original plastic because the bonded plastic is thicker than the original was.
** Notes to keep in mind..........
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** When you do this process, do NOT take a shortcut and try to do something with a soldering iron: That is wrong. This instantly melts the plastic and it will lose its plastic properties in doing so.
** If you see smoke at anytime, you are doing it wrong and it is simply too hot. You should not smell it burning or see any smoke EVER.
** The key to success in plastic welding is to be squeaky clean and well prepared ahead of applying any heat.
** It is better to apply patches in thin layers like a milk container one on the other instead of laying down a thick patch and melting the whole thing into a ball of resin.
I hope this helps someone out here or at least gives confidence in doing it yourself.
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Stan
1988 Fiero GT.. All stock.. for now.
