Hi all. just wondering if any one has had any experience with plastic welding. My buddy is building a 1929 model a with a small block Ford c/4 in it. The project came with two plastic saddle bag type gas tanks and one is leaking around the fuel bung. Tried doing some slight grinding and prep work and using some special epoxy, two part sealant it stopped for a bit and then started slightly again. Would hate to have to get two new tanks again. Any ideas would be appreciated. thanks. YRUHOT........Doug
The tank is probably HDPE. This can be heat welded best w/ HDPE filler. Polyethylene is the poor mans teflon and I don't know of any epoxy that can get good adhesion. I use a sheet of polyethylene to mix epoxies because it cleans off so easy.
As a side note, some of the older plastic tanks do not do well with Ethanol gasoline. I have heard that the tank makers have addressed this problem but some of the older ones were being eaten up when using Ethanol gas. We were replacing a lot of plastic and fiberglass tanks in boats when I was in that business. Don
Thanks for the input so far. Not good news for my buddy. Yes that stuffis like teflon when trying to glue.yruhot''''''''''doug
Hey Yellow dog, could you tell me more about hdpe fillers? such as were to find them and what else they might be used for? Much appreciated. yruhot..Doug
Harbor Freight has a welder for about $70 with adjustable temp. This is important for the melting point of the base material and filler rod. There are tons of info and suppliers just google it...also some really good how-to's on Youtube. I would bet the tank is HDPE ...take a close look for signs of crazing before investing much time though. If the bung hole is the only damaged area its probably worth repair. The sealing surface might not be perfect after welding, but you can probably dress up. Alternatively if you can reach to the inside of the tank maybe you could just install a bung fitting sandwiching the tank. If its just threaded into the tank, that's always going to be suspect dan
I've sealed cracks in plastics that epoxies wouldn't stick to by trimming a piece off somewhere(flange) and using a hot soldering iron, melt the piece/ tank together. Used this process on cracked battery cases also. this way you know the two parts are the same type plastic and should bond.
I totally agree with fordor41. He knows what he is talking about. We in the body business fix all kinds of plastic parts.The best results for a crack or tear is what he said.Plastic epoxy is good also but melting it together with a electric solder gun is the best. Think about this, if it was steel would you prefer adhesive to bond together or weld! Melt the two together! Just my 2 cents.
The plastic tanks are reasonable in price, would replacing it be easier and safer. The possibility of a unique shape and size may limit just repacing however. I just am spooky about gas leaks. Good luck. ~sololobo~
I agree. Cut down/drill out the bung and install a bulkhead fitting made for fuel cells. You should be able to go in through the sending unit hole. Repairing a bad existing weld or a defective component is iffy at best and not worth the risk. I'd go mechanical fastner with seals or get a new tank. http://www.jegs.com/i/JAZ/547/832-108-11/10002/-1