[Sofa_King_Tired]

Hi guys,
I've got a small leak on a fuel tank right where it bolts to the lawn tractor. I've tried using a soldering iron to melt the plastic. That holds for a few days but eventually it leaks again. What else can I do to seal it up?

 

[Oscar Leroy]

Interesting question. I have managed some repairs on hdpe items using a heat gun to melt it till it's pliable and molding things into shape. But I have never had to fix something containing a liquid. I'll be following this to see how others do this too.

 

[Gizmo2]

Is it a crack or a hole?

 

[DBCSteve]

Did a quick Google search and found several sites (here’s one below) that say do not use epoxy since it dries rigid and hdpe will expand and contract with temperature variation (and/or will get dissolved by fuel). Several sites say use a heat gun and filler. The only experience I have that is similar is ski base repair, and ptex (a type of polyethylene) is readily available. Not sure if hdpe filler is the same as ptex filler, but could be (see Amazon link below).

How to Repair a Polypropylene Gas Tank

You cannot repair a damaged polypropylene gas tank with epoxy or a plastic tank repair kit, because gasoline will quickly dissolve the epoxy and the leak will reappear. Polypropylene is a thermoplastic, which means that you can use heat to melt the plastic and create a permanent repair in the...

itstillruns.com

Edit: polypropylene and hdpe are different plastics but perhaps similar to repair, need to find the right filler — HDPE and PP Plastic: What's the Difference? | Acme Plastics

Amazon.com: High Density Polyethylene (HDPE) Plastic Welding Rod, 1/8" diameter, 30 ft., Natural: Automotive

Buy High Density Polyethylene (HDPE) Plastic Welding Rod, 1/8" diameter, 30 ft., Natural: Arc Welding Equipment - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[Kurt L]

Hi guys,
I've got a small leak on a fuel tank right where it bolts to the lawn tractor. I've tried using a soldering iron to melt the plastic. That holds for a few days but eventually it leaks again. What else can I do to seal it up?

I worked in the automotive prototype and design industry for 30+ years. All plastics are different. Some plastic such as ABS can be epoxied together with specific adhesives. Other plastics such as Polypropylene and HDPE need to be “ plastic welded” together at specific temperatures due to the fact that if it is too hot the plastic compounds will crystalize and be worthless.

The Drader Plastic Welder is the industry standard for fixing and repairing plastic. Unfortunately the welder is very pricey and the average person cannot justify buying it.

Drader Injectiweld | Plastic Injection Welder

The Drader Injectiweld is the best plastic welder with easy to use hand held operation for strong plastic welding to thermally bond and repair most plastics.

www.drader.com

A hot air welder is your second best option but they are not bullet bullet proof like the Drader.

Beyondlife 1600W Plastic Hot Air Welder Heating Gun PVC Vinyl Rod Welding Hot Gas Pistol Tool - - Amazon.com

Beyondlife 1600W Plastic Hot Air Welder Heating Gun PVC Vinyl Rod Welding Hot Gas Pistol Tool - - Amazon.com

www.amazon.com

Unfortunately there is not an easy solution to the best of my knowledge. Plastic welding at the correct temperature with HDPE filler rod is your best bet. The filler rod can be home made from HDPE flat stock cut into strips if needed

 

[Sofa_King_Tired]

Oh and open to ideas of mounting an aftermarket tank. I tried looking a few up but not sure how I would mount it. I've got an lt166.

 

[Sofa_King_Tired]

Thank you both for the reply. Yeah I've seen comments about epoxy,jb weld and seal all. Thats why I tried the soldering iron first. I wonder of its not cleaned enough or getting to hot. Seems to hold for a few days while I work on other parts then out of no where it starts leaking. Its like its slowly dissolving. I will try again make sure it cleaned and try to use a lower temp as well!
I can't justify 200to 300 $cad. For a new or used tank.

 

[Kurt L]

Thank you both for the reply. Yeah I've seen comments about epoxy,jb weld and seal all. Thats why I tried the soldering iron first. I wonder of its not cleaned enough or getting to hot. Seems to hold for a few days while I work on other parts then out of no where it starts leaking. Its like its slowly dissolving. I will try again make sure it cleaned and try to use a lower temp as well!
I can't justify 200to 300 $cad. For a new or used tank.

I doubt a soldering iron will work. But it doesn’t hurt to try again. Hot air welder with HDPE soldering rod is your best shot at a permanent repair.

 

[Kbar]

JB weld that sumbich

Is it a crack or a hole?

Depends on how close you look

 

[Oscar Leroy]

Depends on how close you look

Oh, I bet a real close-up of that would make an interesting picture! 🤔😉

 

[X758]

I’ve never tried to weld hdpe in the way you are talking but I have fused (welded) miles of hdpe pipe in a fusion machine. The heating plate is set at 475 degrees no matter the thickness or diameter of the pipe. The difference is the pipe gets squeezed together and you need a filler of some sort.

 

[Seasled]

I’ve had really good luck with JB Weld on plastic fuel tanks

 

[Josh.]

Get it soft and push some short 1/4" staples into it with the pointy ends sticking out across the crack.

 

[Sofa_King_Tired]

So I pulled the tank and used grinded the previous "fix" down and found a large crack i didnt notice the first time. I cleaned it all up and instead of using a soldering iron I used a small wood burning tool I had. It doesn't get as hot and seemed to have melted the plastic a lot better. I pressurized the tank for a few min and didn't see any bubbles. Mounted it and put some gas back in. Ill check on it in a few days see if the leak comes back. I dont actually use the mower to cut grass, just rebuilding it to drive daughter around the yard(mower deck completely removed of course.)
I've got my govenor set and just need to make final adjustments on the carb. Next step is to replace the drive belt. Noticed some cracks on it and was slipping a lot on the winter driving in the snow ❄ 😃

 

[rydplrs]

We used to get hdpe welded at the local plastic shop for my last job.

 

[Sofa_King_Tired]

so far so good, been 2 days and no leak yet. see what its like by the weekend. i guess taking your time and doing it properly really helps lol.

 

[pede]

I just fixed a big hole in a gator tank, used a heat gun to get it back in shape then after a lot of research used Loctite epoxy, only one that said will work with some plastics, 6 months and stilling holding.

 

[BWV]

If it does it again, look and see if you can figure out the source of the stress thats causing it to crack, ans see if you can do something to "unload" that stress. That way your crack fix will be "pluggin a leak" instead of a load bearing repair.
Also... if you can get a hot air rework station for SMT electronics, and find out the temp for the plastic, that might make a good tool for you.
Lastly.. for your "welding rod" .. look for webbing, mold flash, or other "extra" plastic on the tank that you could maybe scrape, grind, or cut off for welding material..good to use the same plastic for this type of repair.
The staple idea above does work... and if you can melt a layer if thin plastic over it..the staple wont rust and fail as quickly.
Good luck!!!

here's an inexpensive rework setup..

Hot Air Rework Station, 110V SMD Hot Air Gun Soldering Station 100-500 °C Heat Gun Temperature & Air Speed Adjustable LED Screen Display with 3 Air Nozzles Desoldering Pump Anti-Static Tweezers Cutter - - Amazon.com

Hot Air Rework Station, 110V SMD Hot Air Gun Soldering Station 100-500 °C Heat Gun Temperature & Air Speed Adjustable LED Screen Display with 3 Air Nozzles Desoldering Pump Anti-Static Tweezers Cutter - - Amazon.com

www.amazon.com