Plastic Gas Tank Repair

[bill]

I'm after a quick fix to repair the IMS plastic gas tank on my DRZ.

I'm currently in Pattaya, over from Cambodia, and noticed the tank is weeping from underneath where the rear mounts bolt on.
The plastic around the mounts is slightly cracked.
Hoping to head back to Cambo tomorrow so wondering what type of stuff I can easily source to stop the leak.

 

[johnnysneds]

I'm after a quick fix to repair the IMS plastic gas tank on my

Hey bill, I think you would be struggling to "quick fix" repair a plastic fuel tank safely. Just did a quick search to confirm and came up with the below. Is it really worth the risk of fuel dripping onto the header!!!


"Epoxy WILL NOT WORK. The problem is that the polypropylene molecules that the tank is made of link with the fuel molecules in the tank, and the plastic gets contaminated. The fuel actually passes thru the plastic on a molecular level. That's why graphics bubble if they don't have holes in 'em; that's why they turn brown; and that's why "natural" or "clear" tanks turn brown after a couple of years if you don't drain the fuel when the bike is sitting. Epoxy is VERY VERY sensitive to surface prep and cleanliness, and since you can't get the fuel out of the plastic (remember, it's on the molecular level), a good fix just ain't gonna happen. A better bet might be either a urethane (again, surface prep is critical...good luck) or an acryllic adhesive. Acryllics are very agressive at the molecular level and are not as sensitive to surface prep. They are also resistant to hydrocarbons (fuels and oils). The problem with acryllic adhesives is that they have very low strain to failure (are very brittle), and are also pretty sensitive to high and low temps. You might try some polysulfide aircraft fuel tank sealant if all you want to do is plug the hole...but it will not add strength and the crack will continue to grow (and create new leaks). A commercial product called "Kreem" is kinda an equivalent. The thickness, contour, and fuel contamination make it not a candidate for plastic welding, either.

Not to piss in the punch bowl, but you aren't going to be able to make a durable fix on that tank. Most cars come with rotatinally molded polypropylene fuel tanks these days. Call your local Ford, Chevrolet, or Daimler Chrysler dealer, and ask the service department if they can fix a cracked plastic fuel tank. They won't help you."

 

[madjbs]

Can you not drain and rinse the tank and then plastic weld it? We plastic weld polypropylene kayaks so I think it should work with a fuel tank too (as long as you make sure there is absolutely no chance of any fuel being left in it!).

EDIT: oops, didn't read the bit about plastic welding.....I still think it would be possible depending on the crack, but you are probably best just buying a new tank...

 

[KTMphil]

Get the area completely free of benzine and use some solvent to get the cracked area completely clean.


Go buy a 2 litre plastic milk jug from 7-11 empty it out and get it clean.



with a cigarette lighter, hold the flame on the plastic milk jug and let the melted plastic drip into the cracked area of the tank. try and open and close the crack to get the melted plastic inside the crack.


I've heard people have had success with this and it will bond.


Good Luck.





Another option - get all the benzine out of the tank




Put some red Pematex high temp. silicone on the outside of the cracked area and with a vacuum cleaner sealed around the fuel fill, suck the silicone all through the crack and let cure

 

[KMA]

In the states I would take mine to an RV repair shop. The material is the same as the water holding tanks on RV's. The other option was p-tex. It's the stuff you light and then drip into & fill holes on the bottom of snowboards or skiis. I always carried a stick on the trail. Both of which probably won't help you out here but you never know. Good luck!

 

[bill]

Thx for all the suggestions

The quick fix got me home..

I went to HomePro Monday evening and checked out their range of adhesives/repair gunk.
3 different Thai attendants gave me 3 different recommendations.
In the end, nothing seemed exactly what I needed so I went for something I knew would stick, at least initially

The cracks where fuel was leaking were just below the dotted black lines. I simply ran a few beads of superglue along the cracks and allowed to dry overnight on the balcony of my hotel room.

The dotted lines on the above pic show where the corbin seat was putting undue pressure on the tank. Rather than being supported by its own mounts on the sub frame, it was resting on the tank. That was the reason for the plastic around the rear bottom mounts to crack.

I remounted the tank in a way to take pressure of the mounts and rode 600km back to Cambodia. No leaks yet but I suspect the superglue will be brittle and crack under any offroad use.

Not sure what to do next for a long term fix.

 

[LivinLOS]

Would a hot glue gun be able to get it deep enough into the cracks ??

 

[Faz Harris]

Madjbs and KTMphil have given the correct answer. Identify the material used. Most Plastic tanks are of PE. If your tank is made of PE, the plastic weld would be an ideal solution. All you need is either a heat gun or a hair dryer or a lighter.(make sure your tank is clean from any fuel substance).
Grab some engine oil plastic containers of the same color of your tank. Look at the bottom and see whether there are any triangular markings with the letters HDPE.
Cut the container into small strips . Then use the heat gun to soften these strips. Heat the tank (with the cover removed of course), until it is mildly hot and a bit soft (take care not to burn a bigger hole there)...and then reheat the HDPE strips till the melt and cover the cracks on the tank. After the cracks are covered enough, allow to cool and sand the that area so that it looks normal.
Good luck. This is how I plastic weld by Mission kayak.

 

[Faz Harris]

Another option wud to go for Bostik Plastic Bonding Adhesives. Read the adhesives and if it sates, "Plastic Bonding" then it shud be ok for a temporary fix. But I am sure plastic welding can be sort of an almost permanent repair.
I have even seen someone using mineral water bottles as a material for plastic welding, and it works, provided the material is made from HDPE.
Some other HDPE made items are yogurt containers, milk palstic containers etc.....As for plastic welding, I suggest u try it on another palstic container till u get the hang of it. I believe it would work. Anyway, u got nothin to loose. Try it and if you don't like it, buy a new tank.