Cracked plastic fuel tank, possible repair method?

[AndyAndyAndy]

Fuel tank is cracked right at the neck. Just under the thread to screw on the cap. It goes around 50% of the circuit. Usually I would drill holes, zip-tied it, put epoxy/glue around. But because of threads I can't do any of that.

Do you have any idea how to fix that? I have hard time finding replacement tank. I would prefer cheaply fix this one anyway.



I just found that tank in promotion for 8$ including shipping

 

[Snaker]

Aw, the broken fuel tank neck. In the snowmobile world sheds and swap meets are full of those things. Hard to fix but no one wants to throw it away.
The most likely cause is letting the gas pump gun hang while filling. The weight of the gun/hose pry's against the sides till crackity crack.
I have repaired a few but it depends on individual tank. Some are fixable and some aren't. Don't hurt to try.
Just stay aware that your dealing with gas fumes if your fix includes heat.

 

[itsid]

if one knows the plastic... one could weld it ;9

(likely a PE tank, PE filler rod and a soldering gun and it'd be as good as new.. given you can clean it properly and reach the cracked spot well enough (ideally from both sides)

'sid

 

[7thofa2nd]

Like Sid said...
You may also try using a hot glue gun. Look all around the tank for any symbols or abbreviations that may tell you what kind of plastic it is, then do a search for repairing that type of plastic.

Types of Plastics

Identify the types of plastic we use every day by their symbols. Find out what they are, how we use them and which plastics we can recycle.

www.pureplanetrecycling.co.uk

Repairs...

Identify Plastic for Repair

 

[madprofessor]

Sid's got the right and proper repair idea with using something to MELT the plastic and seal ITSELF back up. That's actually plastic WELDING instead of soldering, regardless of what that mfr. calls their product. Melting the crack itself, and mixing the semi-molten sides together to become one again is the best way there is, while glue guns and etc. just lay a sealer something or other across the the surface of the still-existent crack.
Unfortunately, if that crack is between some of the threads (weakest part of the neck), you can only work on the inside of the neck, but that might be good enough.
However, if you're willing to sacrifice some threads to get a solid melt repair, it's just plastic threads! You can carve new threads into it with a razor knife, then run the cap down over it to finish the threading job.
Or you could raid the piggy bank for a new tank, the shape, capacity, color, etc. you really want.

 

[7thofa2nd]

Sid's got the right and proper repair idea with using something to MELT the plastic and seal ITSELF back up. That's actually plastic WELDING instead of soldering, regardless of what that mfr. calls their product. Melting the crack itself, and mixing the semi-molten sides together to become one again is the best way there is, while glue guns and etc. just lay a sealer something or other across the the surface of the still-existent crack.
Unfortunately, if that crack is between some of the threads (weakest part of the neck), you can only work on the inside of the neck, but that might be good enough.
However, if you're willing to sacrifice some threads to get a solid melt repair, it's just plastic threads! You can carve new threads into it with a razor knife, then run the cap down over it to finish the threading job.
Or you could raid the piggy bank for a new tank, the shape, capacity, color, etc. you really want.

True, using a glue gun won't nessesarily meld them together... unless you allow the hot tip of the glue gun to melt the original plastic too, thus blending the plastics together. A glue gun is plastic welding, but It really depends on the type of plastic. I've done both with success. With that said. Sid's idea is the surest... just match up the welding stick with the same plastic as what you're attempting to weld.

 

[rockman96]

Don't know how well this would work on the area of the tank where yours is cracked, but I had a push mower that the plastic tank got hit on the side with a branch stub of a juniper, and subsequently received a puncture/split on the flat area of the tank. I scuffed the damaged area and the surround with some 80 grit paper, cleaned it several times with lacquer thinner and a rag, and dried it well with air... Then I mixed some JB Weld (original formula) and spread it over the area. I applied some regular kitchen tin foil over that and 'massaged' it on, then went over the top of that with another coating of JB Weld and let it all cure for over 24 hours. That tank repair held for the several years I used that mower before I scrapped it.

 

[madprofessor]

rockman, you rock man! I dearly love 2-part epoxy JB Weld. Have probably used every brand there is, JB Weld is the winner.
Andy, my current 212 got a "hole" punched in the top of the case from the inside when the governor arm slid down into the case. Hard to see, just a raised ragged little spot, but oil got pumped out of it when running. Cleaned and rasped that little flat section on top (little bigger than a matchbox), and filled it with a little lake of JB Weld. Cured for 3-4 days, cranked it up, it's solid as steel, no leaks, no peel when heated up, all good.
Home Depot sells a series of JB Weld 2-parts. Read the labels, pick the one that's for plastic and is fuels-proof, don't worry be happy.