Has anyone had experience using a sealant or adhesive to repair a crack in a "poly" gas tank? I have tried 5200 and J/B weld. Sanded surface and cleaned with acetone prior to application, but neither would stick to plastic surface
plastic fuel tank repair
- Thread starter Slipin Away
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The tank is most likely polyethylene. One of the nice qualities of PE is that nothing sticks to it, as you are finding out. They can be repaired by welding and I believe there is one company that makes a repair glue, but can't recall the company's name.
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TIPS FOR WELDING THERMOPLASTICS - King Plastic Corporation
From the archives IAPD Welding is the process of uniting surfaces by softening them with heat. When welding thermoplastics, one of the key components is the material itself. For as... Read more »
www.kingplastic.com
Nothing really sticks to poly except Permatex 2. Problem is that it's only a sealant and not an adhesive. If you can provide a picture of the leak, there may be a possibility of "flanging" it for a repair. It's also known as desperation.
Plastic welding is also a possibility but requires practice or you may destroy your tank. Depends on the location of the crack.
Plastic welding is also a possibility but requires practice or you may destroy your tank. Depends on the location of the crack.
That's a tough one. MAY be able to weld it, but high risk of contamination. For adhesives to stick to PE the surface must be activated. Can use a chemical activator like this system:
While it should stick OK it may not be a perfect seal and you risk leaks.
Or use a flame treatment:
Obvious risk using a flame on a used gas tank! I do not recommend it!
In the end your best and safest bet is to replace the tank.
While it should stick OK it may not be a perfect seal and you risk leaks.
Or use a flame treatment:
In the end your best and safest bet is to replace the tank.
a. Repairing a poly gas tank is a REALLY bad idea. PE is very tough to bond, it failed either because it was UV damaged or over stressed by pressure, and the repair will almost certainly not meet standards. Gasoline is dangerous stuff. Don't do it.
b. Gasoline permeates the plastic to some extend, meaning it is INSIDE the plastic. You can't wipe it off. This makes it VERY difficult to repair both plastic and fiberglass tanks that have seen gasoline or fuel for long periods. If it must be done for a small hole, a mechanical patch is often safer (someone poked or drilled a hole, not a crack), because bonding is never certain.
If you are going to bond PE, I've done this on water tanks and fishpond liners, and had the patches last >7 years.
* Wipe clean.
* Sand 80 grit. Rough.
* Flame the surface with a torch to denature the plastic. Just enough to make it turn dull, don't melt it.
* Bond a fabric patch (something like Sunbrella) (you need fabric to spread the bond area and add flexibility--about 1-inch overlap) using either Loctite PL S-40 or G-Flex. 3M sealants are not very good on PE and other epoxies suck. But G-Flex is quite good, approaching the strength of a weld if done well. Wet the fabric and blend, like laminating fiberglass.
But NOT gasoline or fuel tanks. For starters, 3M5200 is not gasoline resistant--it had zero chance of working.
(refinery engineer and licensed tank inspector)
b. Gasoline permeates the plastic to some extend, meaning it is INSIDE the plastic. You can't wipe it off. This makes it VERY difficult to repair both plastic and fiberglass tanks that have seen gasoline or fuel for long periods. If it must be done for a small hole, a mechanical patch is often safer (someone poked or drilled a hole, not a crack), because bonding is never certain.
If you are going to bond PE, I've done this on water tanks and fishpond liners, and had the patches last >7 years.
* Wipe clean.
* Sand 80 grit. Rough.
* Flame the surface with a torch to denature the plastic. Just enough to make it turn dull, don't melt it.
* Bond a fabric patch (something like Sunbrella) (you need fabric to spread the bond area and add flexibility--about 1-inch overlap) using either Loctite PL S-40 or G-Flex. 3M sealants are not very good on PE and other epoxies suck. But G-Flex is quite good, approaching the strength of a weld if done well. Wet the fabric and blend, like laminating fiberglass.
But NOT gasoline or fuel tanks. For starters, 3M5200 is not gasoline resistant--it had zero chance of working.
(refinery engineer and licensed tank inspector)
Yup. I figured that he has a leak in the plastic/poly tank for his dinghy (or gen-set) gasoline-fueled engine.
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Not too clear which fuel tank the OP refers to. Let's wait and see the purpose of the "gas" tank.
a. The OP said gas.
b. Yes, diesel too, enough that you can't be SURE of a good bond. Refinery experience with many petroleum products. Not worth the risk.
c. Yes, probably the tender tank. Another reason not to risk it (cheap enough).
If we assume that the OP knows the difference between diesel and gas and take him at his word, then we must be talking about an outboard fuel tank, which is not worth the effort to repair.
However, if Hunter is using plastic fuel tanks, then someone on here should pipe up and clarify that for the rest of us, please.
However, if Hunter is using plastic fuel tanks, then someone on here should pipe up and clarify that for the rest of us, please.
My 1999 Hunter has a poly tank so I assumed the OP's 45 CC (later model) has a poly tank as well.
If I could afford a 45 CC, I wouldn't be repairing an outboard fuel tank. I recently replaced the fuel tank in my 2.5 Merc outboard for about $85.00. Pretty cheap in terms of boat units.
Always looking on the bright side of things, eh
?
Absolutely. Way too much doom and gloom. Maybe they used a steel tank for fresh water.Always looking on the bright side of things, eh
First taste of boat's water on a month long excursion ........................
Let's see you put a positive spin on this design flaw.
uncle Ralph, I 'tol you not to drink from THAT tank.
Assuming this is a large fuel tank integrated into the boat AND the crack is small have you considered using some type of flanged fitting that would be normally used as a drain or fill fitting?
Drill the ends of the crack so it doesn’t get any bigger, remove enough of the area to insert the flange - fitting and put a shut off valve to seal the new fitting.
Probably not a legit repair, just thinking outside the box.
When I refer to a flange type repair, I'm thinking more of a rigid metal plate applied to a crack on a flat poly surface. The plate is held down by screws into the poly tank and there is Permatex 2 between the plate and tank. Only Permatrex 2 sticks to poly, but only as a sealant and not an adhesive. As you say, drilling the ends of the crack to remove the stress raiser is every bit as important.
A repair such as this on a larger boat's diesel fuel tank would be acceptable due to a) the high cost of a new tank b) the even higher cost of installing the new tank, and c) relative safety of diesel fuel as compared to gasoline.