[GMCnet] Black tank repair - Plasti-Mend

[Eric Monce]

For any interested GMC owners - My 77 Kingsley had a leak at the rear of the blank tank just above the tank strap. I tried the Plasti-Mend product and it worked great. It's available through the Plasti-Mend web site or Amazon.
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[Eric Monce]

Sorry guys - I take it back - it lasted for a while and then started leaking again.....
--
E.Monce
Escondido, CA
77 Kingsley

[gene Fisher]

I "plastic welded " mine, and the same thing happened

I put in a new tank
gene

--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html

[Bill Wevers]

I mended mine with the ABS pipe cement. It worked for a few years.
Then it started leaking again.
I recently took the tank out and patched it up again.
I hope it holds.

Regards,
Bill

[Emery Stora]

For a proper "mend" the material that you use has to dissolve the plastic and then dry or solidify. This can be done by heat or in the case of some plastics by a solvent.
However, there is no solvent for either the water tank which is polyethylene or for the holding tank which is polypropylene (on most GMC models). So for those plastics the only way to do it is to melt the surface with heat and fuse in some more of the same material. That is what plastic welders do. Some have been able to repair water tanks by using a soldering iron and melting in some strips of a plastic milk jug which is also polyethylene. But in most cases this will harden the plastic as it evaporates off some of the plasticizers (chemicals that keep it soft and flexible). If it is hardened it will easily crack again.
Use of a commercial plastic welder keeps the heat at just the right temperature without overheating it.

The patching compounds that are sold to repair tanks are basically epoxy or silicone compounds that stick to the tank solely by a mechanical bond. That is why they all say to sand the surface before applying them. By roughing up the surface it allows it to "grab" and stick better. These are often good for a temporary patch but will eventually break loose and start leaking again.

Plastics that work well with solvent type products are styrene or vinyl plastic based products such PVC (Polyvinyl chloride) pipe (usually white but also comes in clear, grey or black and even other colors) or the black pipe drain pipe ABS (Acrylonitrile butadiene styrene).

Emery Stora
77 Kingsley
Frederick, CO

[Emery Stora]

On Nov 28, 2012, at 2:20 PM, Bill Wevers wrote:

>
>
> I mended mine with the ABS pipe cement. It worked for a few years.
> Then it started leaking again.
> I recently took the tank out and patched it up again.
> I hope it holds.
>
> Regards,
> Bill
>

It won't. You are lucky that it held that long. ABS cement will not dissolve the surface but merely coat it Sort of like putting duct tape over it. It will hold for awhile but eventually fail.
If you have the tank out take it to a plastic welder (check the yellow pages under plastics) and have it mended properly.

Emery Stora

[Jim Bounds]

Plastic deteriorates over time and when it does it also shrinks.  This is why many times you will have a crack  on an edge or a star crack around a fitting.  The plastic shrinks and cracks.  If you fix that crack, there's a good chance it will crack again or somewhere wlese because remember, the plastic is deteriorating.   I've been asked what the 1/2 life of these plastics are-- I would say now.  If you want to really fix your system from leaking and the best way is simply replace the tank, fittings, downpipe and while you're at it stop launching carriers down a 3" pipe, install a maserator.  Just close your eyes and write the check, remember the world ends Dec. 21!
 
Jim Bounds
----------------------


________________________________
From: Emery Stora <emery...@mac.com>
To: gmc...@temp.gmcnet.org
Sent: Wednesday, November 28, 2012 4:29 PM
Subject: Re: [GMCnet] Black tank repair - Plasti-Mend

[Eric Monce]

I just have to try one more thing before putting out the big bucks - this is supposed to be for polyethylene and polypropylene - I'll let you know how it goes.....

TAP Plastics Poly-Weld Adhesive check out their website.....

--
E.Monce
Escondido, CA
77 Kingsley

[Gary Berry]

Hey;

I have a leaking water tank in the Stretch. I took it out and
took it to an RV place to see if they could find a replacement. They
couldn't. I asked them then to try and fix it, and they tried, but it
is now leaking again (after the first trip). So sometimes you can't
just write a check to get a new tank, but now I will try to find a
"plastic welder" in the yellow pages (remember I live out here in the
middle of no where (kids call it Hooterville). Thanks for the tip.

--
Gary and Diana Berry
73 CL Stretch in Wa.

[RC Jordan]

If I were going to try the adhesive repair route I'd use some fiberglass drywall tape to bridge the cracks. Its mesh is open enough that the adhesive can easily penetrate down to the tank. And it's cheap enough to build out several layers. That glue isn't cheap though.
--
77 Royale "Retro Chic" (currently at GMCcoop)
Elizabeth City, NC
1 hour south of Norfolk VA
1 hour west of Kitty Hawk, NC

[gene Fisher]

did you look here
http://www.bdub.net/Ardemco/index.html

gene

--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html

[Rob Mueller]

G'day,

I listened to Jim and this is how we fixed the black tank on Double Trouble at the COOP.

http://www.gmcmhphotos.com/photos/g6238-black-tank-repair.html

That was four years ago and so far so good!

Regards,
Rob M.

-----Original Message-----
From: Jim Bounds

Plastic deteriorates over time and when it does it also shrinks.  This is why many times you will have a crack  on an edge or a star
crack around a fitting.  The plastic shrinks and cracks.  If you fix that crack, there's a good chance it will crack again or
somewhere wlese because remember, the plastic is deteriorating.   I've been asked what the 1/2 life of these plastics are-- I would
say now.  If you want to really fix your system from leaking and the best way is simply replace the tank, fittings, downpipe and
while you're at it stop launching carriers down a 3" pipe, install a maserator.  Just close your eyes and write the check, remember
the world ends Dec. 21!
 
Jim

[Matt Colie]

Gary Berry wrote on Wed, 28 November 2012 18:39

> Hey;
>
> I have a leaking water tank in the Stretch. I took it out and took it to an RV place to see if they could find a replacement. They couldn't. I asked them then to try and fix it, and they tried, but it is now leaking again (after the first trip). So sometimes you can't just write a check to get a new tank, but now I will try to find a "plastic welder" in the yellow pages (remember I live out here in the middle of no where (kids call it Hooterville). Thanks for the tip.
> --
> Gary and Diana Berry
> 73 CL Stretch in Wa.

Gary,

Without know where you are, I can not even offer suggestions, but I will give you two pieces of "Free" advice.
First, do not bother trying to weld PE or PP with air. You have to have nitrogen. Heat and oxygen will actually make it unweldable. So, don't both with the harbor fright part with a built in blower.
Second, what you want to search out are plastic fabricators. If you talk to them nicely, they should be able to help. When the yellow pages are no help, go to Thomasnet, this is an industrial process.

Matt

--
Matt & Mary Colie
'73 Glacier 23 Chaumière (say show-me-air) Just about as stock as you will find
SE Michigan - Twixt A2 and Detroit

[Kerry Pinkerton]

Gary Berry wrote on Wed, 28 November 2012 17:39

> Hey;
>
> I have a leaking water tank in the Stretch. I took it out and
> took it to an RV place to see if they could find a replacement. They
> couldn't. I asked them then to try and fix it, and they tried, but it
> is now leaking again (after the first trip). So sometimes you can't

> just write a check to get a new tank,...


Jim K has them: http://www.appliedgmc.com/prod.itml/icOid/836 and I'm sure that Jim Bounds at the Coop does also. For $250 I wouldn't spend the effort trying to fix it and risk being on a trip when it failed and you loose your water or, even worse....much worse, you wake up to a wet floor and unhappy spouse. 8o
--
Kerry Pinkerton

North Alabama, near Huntsville,

77 Eleganza II, "The Lady", 403CI, also a 76 Eleganza being re-bodied as an Art Deco car hauler

[Chris Choffat]

The Polyethylene is so brittle, nothng works. I welded my tank several times, still leaks. will be replacing it.
--
-Chr$: Perpetual SmartAss
Scottsdale, AZ
"The Escape Pod" A 77 Ex-Kingsley Featuring: Olds 455, Manny Power Drive, 3:21, Rockwell, Jim B QJET, Quadra bag. Still needs paint!

Photosite: Chrisc "It has Begun"