Fuel Tanks Cracking

[Honda Hoarder]

I have had a few fuel thanks crack lately, they had unblocked breathers and the fuel caps were loose.
Some of the tanks had not had fuel in them for some time

So does anyone have any tips to stop this. 


Thanks

[TT5 Matt]

id say the plastic has dried out greatly reducing its flexibility a lot and todays fuel with lots of ethanol leaches polimers (spellin)out of the plastic. Brentj on here wouldn't buy a plastic tank unless the seller was prepared to fill the tank full with fuel for 2 weeks to see if it was going to crack and lots of guys who sanded/polished their old tanks only for a lot of them to crack on the 1st outing. sometimes your better to buy a new Clarke tank.

[Honda Hoarder]

Thanks for the reply

Brought a Clarke tank for my 84 CR 500 and it's crap, the colour is way off and the fitment is shit also $$$$


Going to do a few tests

Put another 84 tank in a clip lock tub with 3 small tins of pre mix fuel around it.
Think after a week I'll spray the outside of the tank with pre mix in a Wurth bottle
Also after another week thinking of a fuel soaked rag stuffed inside the tank

[David Lahey]

Dungar Pilot on this forum treated a ~1984 plastic Italjet trials bike tank by immersing the whole thing in a big metal tank of petrol. From memory I think it was successful
http://www.trials.com.au/forum/viewtopic.php?f=16&t=4785&hilit=italjet&start=2000

[geoff]

I have filled plastic fuel tanks that have been stood for many months with engine oil to the filler and left for another month. Emptied the oil out and filled up with pre-mix and up to now no problems.
I know if tanks are left empty for any length of time they do crack and usually along the fuel level in the tank.

[MEREA]

I have an 84 CR500 tank that  has cracked next to one of the lugs underneath. I ground the crack out with a die grinder and filled with an epoxy plastic glue. It did last a year or so, but after being empty for a few years it has cracked further and now leaks again. Has anyone had any luck with plastic welding?

[PeterC]

Plastic welding does work if
The joins are clean, the plastic filler is the same as the tank plastic and welded/melted together just like welding metal

Cracking etc happens like metal when unsupported, stretching or stressing same as metal.

If unseen you may be able to add a patch etc

[MEREA]

OK cool. There is a plastic welding place on the coast, I might just take it in there for them to deal with

[Husk72]

Let us know how the plastic welding goes Andrew. I have a crack in my 86 CR500, that is fairly clean, and straight.


                                                                                                     Cheers, Mark

[arwtee]

If it is only fine cracking, What about a fuel tank sealer paint?
I used some stuff many years ago which was very thick and rubbery on a tank which had some fine cracking and it worked for a long time. The cracks filled up with the paint and sealed themselves.
I strapped the tank to a cement mixer with sand and gravel in it. After a while the interior was perfectly clean and nicely abraded and once dry ready to paint.
Rob