ABS or Polyethylene black water tank ?

[gonorthwest]

I have a 24' 1979 Argosy (minuet, I beleive). The toilet is mounted on top of the black water tank. The black water tank has a crack in it near the outlet that connects to the plumbing, but otherwise appears to be in excellent shape. I'd like to try to repair it, but the owner's manual simply identifies the material as "plastic." The tank is whitish / light gray in color. It is pliable to the touch. Does anyone know what this material is and how to repair it.

Thanks in advance.

[Dave Park]

Does it have a waxy feel? If so it is polyethylene.

[gonorthwest]

It's soft and flexible. Not so sure about waxy. Can you recommend a repair material?

[helmsman]

I have a "67 Safari. I purchased it in the mid '70s. The former owner told me it was in perfect shape. HA! -- On the 1st outing I discovered the Black Water tank was cracked. The dealer told me no replacement tanks were available, etc.

I removed the tank and took it to another A.S. dealer and asked if he had any plastic scraps of the same type of plastic. He just handed me a few scraps that were lying around. I cut them into small bits and put them into a glass jar. Then covered them with acetone. I put a lid on the jar and waited several days. The plastic chips dissolved, creating a plastic slurry in the jar.

I cleaned the black water tank, sand-papering the area with the crack in it. Then I painted the crack with the plastic slurry. I repeated this several times allowing it to dry between coats, untiil I had built-up a good thickness.

I reinstalled the tank and have used it without further problems for more than 30 years.

Just my experience! -- Don

[gonorthwest]

Interesting you should mention using acetone. I found one company with a repair product that specifically calls for prepping with acetone before using their repair material.

Thanks for the response.

[mgmcnamara]

is there a safe, effective way/product to repair thin crack at the top of the clean water tank in a 1982 Classic?

[cojer]

if you know someone who has a plastic welder...or find some of the same type of plastic and use a heat gun and some pliers..heat both tank and scrap carefully until both are soft (don't let the plastic melt! just get it soft) then press your scrap material onto the tank...i was successful with this technique on some water jugs which is basically what a clean water tank is, maybe just a little thicker . i have a friend who has a plastic welder who was able to fix my fresh water tank. but after watching him i decided to try the heat gun and plastic scrap method which is really what a plastic welder is only a little less "high tech"

[Jammer]

Originally Posted by gonorthwest

I have a 24' 1979 Argosy (minuet, I beleive). The toilet is mounted on top of the black water tank. The black water tank has a crack in it near the outlet that connects to the plumbing, but otherwise appears to be in excellent shape. I'd like to try to repair it, but the owner's manual simply identifies the material as "plastic." The tank is whitish / light gray in color. It is pliable to the touch. Does anyone know what this material is and how to repair it.

Thanks in advance.

It's probably polyethylene. ABS is black.

You can try the plastic welding methods described upthread. However, with cracks in a stress area like that, it is difficult to make a lasting weld.

I have had good results with polyethylene using West System G/Flex epoxy. The polyethylene has to be flame treated per the instructions that come with the epoxy in order to adhere properly. If you use multiple layers of epoxy, and perhaps some fiberglass fabric to reinforce the area between the layers, you should have good results.

Originally Posted by mgmcnamara

is there a safe, effective way/product to repair thin crack at the top of the clean water tank in a 1982 Classic?

Same methods apply

[dwightdi]

If the plastic dissolves in acetone or MEK it is ABS. Making a cement up by dissolving some is a good fix for the problem. If it does not dissolve it is likely Polyethylene. If you take a small scrap and burn it, it should smell like a candle. Getting a stick of PE and using it as a filler when you locally heat the tank enough to just barely melt it would be a good way to weld it back together. You might be able to find a plastics fabricator in the yellow pages in some areas that could perform the service.

[purman]

You can by epoxy kits just for plastic. I have used them on my tanks with no problems..

[DGJackson]

Check out West System G-Flex epoxy. This is a product for plastic repair. They have an ad where they cut a roto molded kayak in half and put I back together. I've been using it to patch cracks and holes in various ABS components in the enterior - i.e. interior wheel wells. You can get it at West Marine.