I know this is off track but thought someone might have an answer. I have an old (20-25 years) snapper leaf blower, back pack style which has developed a crack in the plastic gas tank. Any suggestion as to the type of sealant or glue which will stick to the tank to seal this crack? Thanks for any input. A replacement is not available that I have found.

 

If its a fuel tank be pretty careful with any 'fix' you make its not worth the risk sometimes.
That said there are several options - if you glue the plastic you'll need to know what type of plastic it is so you buy the right glue.
I've seen plastic tanks fixed by 'V'ing out the affected area, the filling it with resin, then fibreglassing over the resin for strength.

 

You might call some of the companies such as POR-15 that sells fuel tank sealant. If the crack is not to big/wide. I've used a heated needle to make holes along both sides of a plastic crack and fishing string to close the crack so it doesn't spread. I then fiberglass both sides. I never used it on a fuel leak, so I don't know if the fuel will affect the fiberglass resin. chuck

 

As a rule Polyethylene, what most fuel tanks are made of, does not bond well to solvents or glues. There are a few options one is plastic welding. if you melt a bonding patch (piece of milk carton) to lay over the crack you might get it to seal.
I also googled plastic adhesive and found this. Don't know anything about it but it "might" work.
Weld-On #1829 4oz Kit Multipupose Glue Adhesive

good luck.
brian...

 

I fabricate and weld plastic for a living. The tank is probably some type of polyethylene. There is low density, high density,Linear low density, and several other types of PE. If it is cross linked PE, it is not weldable at all. To weld it you need to have a welding rod of the same type of material. My experience fixing these things is not that good, sometimes you get lucky and find the right welding rod, but sometimes not. I don't do it, because you can spend a lot of time trying to find the right combination, then people don't want to pay for the time because it is way more than buying a new one. I have heard that someone has developed a glue that is marginally successful in gluing PE, but I think it is limited in what it can do. I doubt that it would stand the gas or the vibration.

 

I agree with Brian and Don. I doubt that there will be any fixing a poly tank. At least long term.

 

Didn't Eastwood have an adhesive for this type of problem?

 

I fixed a cracked plastic radiator tank on an 80's camaro with jb weld back in the early 90's and ran it for several years with no leaks. Might be worth a shot.

 

May want to .try some pig putty. This stuff can fix anything.