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Black Tank [message #216334]

Tue, 30 July 2013 21:41

peter bailey

Messages: 367
Registered: March 2009
Location: Gawler, South Australia

Karma: 0

Senior Member

Hi.
I have a fine crack in my black tank under one of the holding straps what is recommended for glueing this?
If I need to do a plastic weld does anyone know what plastic it is so I can use the correct plastic filler rod.
Thanks in anticipation
Peter Bailey
from Ozy (Aussie)

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Re: [GMCnet] Black Tank [message #216336 is a reply to message #216334]

Tue, 30 July 2013 21:54

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

Peter,

Forget about gluing it and fiberglass won't stick to it either.

I had two bad cracks in Double Trouble's holding tanks where some bozo had over tightened the straps and caused the supports to cut
into the corners.

Here's how I fixed it until I can get the black tank out of my spare Avion.

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

Regards,
Rob M.

-----Original Message-----
From: Peter Bailey

Hi.
I have a fine crack in my black tank under one of the holding straps what is recommended for glueing this?
If I need to do a plastic weld does anyone know what plastic it is so I can use the correct plastic filler rod.
Thanks in anticipation
Peter Bailey

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Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426

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Re: Black Tank [message #216338 is a reply to message #216334]

Tue, 30 July 2013 22:00

Galen

Messages: 146
Registered: November 2011
Location: New Virginia, IA

Karma: 0

Senior Member

I patched the sending unit hole on my tank. There are alot of threads about tank repair and the type of plastic this is, and I read through every thing I could find. I think some of the debate on the kind of plastic used for the tank could be due to tanks being replaced over the years. I finally gave up guessing and took some shavings and did a burn test. Mine was PE,so I patched it with a PE plug welded in, then an over sized PE patch over that welded to the tank. I realize your repair is different, but my point is you will find a lot of debates on here about what kind of plastic it is, from ABS to PP to PE. None of us will know for sure because it appears there have been tanks over the years replaced with different materials. I think the shop manual says PP.

Good luck.

Galen Briggs New Virginia, Iowa 1978 Palm Beach

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Re: Black Tank [message #216339 is a reply to message #216334]

Tue, 30 July 2013 22:02

lqqkatjon

Messages: 2324
Registered: October 2010
Location: St. Cloud, MN

Karma: 5

Senior Member

who knows what will hold. but I had the same issue near the corner where the strap was, and here is what I did:

1. used soldering pen and melted tank on crack. I did not use filler, I was very careful.

then

I went with versachem epoxy:

http://www.amazon.com/Products-SR-213-Professional-Holding-Repair/dp/B000786GM6/ref=sr_1_5?ie=UTF8&qid=1375239491&sr=8-5&keywords=versache m+plastic+tank+repair

then I gave it a coat of 3m 5200:
http://www.amazon.com/3M-Marine-Adhesive-Sealant-White/dp/B0065HGC5O/ref=sr_1_1?ie=UTF8&qid=1375239624&sr=8-1&keywords=3m+5200

I messed up and got a normal cure of the 5200. took amost a week to harden. but when it did, it seemed pretty permanant. I would of gotten the fast cure if I was to try again.

I think it is pretty decent repair.

but depending on plastic, it might not last.

here is my write up:

http://lqqkatjon.blogspot.com/2012/10/black-tank-repair.html

Jon Roche 75 palm beach EBL EFI, manny headers, Micro Level, rebuilt most of coach now. St. Cloud, MN http://lqqkatjon.blogspot.com/

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Re: [GMCnet] Black Tank [message #216344 is a reply to message #216334]

Tue, 30 July 2013 22:06

Emery Stora

Messages: 959
Registered: January 2011

Karma: 4

Senior Member

Should be polypropylene unless you have a 1973 where someone reported it is polyethylene.

Emery Store

On Jul 30, 2013, at 8:41 PM, Peter Bailey <bugeye@internode.on.net> wrote:

>
>
> Hi.
> I have a fine crack in my black tank under one of the holding straps what is recommended for glueing this?
> If I need to do a plastic weld does anyone know what plastic it is so I can use the correct plastic filler rod.
> Thanks in anticipation
> Peter Bailey
> from Ozy (Aussie)
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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Re: Black Tank [message #216350 is a reply to message #216338]

Tue, 30 July 2013 22:46

A Hamilto

Messages: 4508
Registered: April 2011

Karma: 39

Senior Member

Galen wrote on Tue, 30 July 2013 22:00

...I finally gave up guessing and took some shavings and did a burn test. ...

How do you do a "burn test"?

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Re: [GMCnet] Black Tank [message #216353 is a reply to message #216344]

Tue, 30 July 2013 23:09

roy1

Messages: 2126
Registered: July 2004
Location: Minden nevada

Karma: 6

Senior Member

Emery Stora wrote on Tue, 30 July 2013 20:06

Should be polypropylene unless you have a 1973 where someone reported it is polyethylene.

Emery Store

On Jul 30, 2013, at 8:41 PM, Peter Bailey <bugeye@internode.on.net> wrote:

>
>
> Hi.
> I have a fine crack in my black tank under one of the holding straps what is recommended for glueing this?
> If I need to do a plastic weld does anyone know what plastic it is so I can use the correct plastic filler rod.
> Thanks in anticipation
> Peter Bailey
> from Ozy (Aussie)
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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Maybe my memory is going but Emery I thought you corrected me a while back and said it was polyethylene and could be repaired with a milk bottle? At any rate melting the correct plastic into the crack with a large soldering iron will fix it but you need to take out the tank to repair it.

Roy Keen Minden,NV 76 X Glenbrook

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Re: [GMCnet] Black Tank [message #216354 is a reply to message #216353]

Tue, 30 July 2013 23:28

emerystora

Messages: 4442
Registered: January 2004

Karma: 13

Senior Member

Roy

That was the fresh water tank. It is polyethylene.

Emery Stora

On Jul 30, 2013, at 10:09 PM, roy@gmcnet.org wrote:

>
>
> Emery Stora wrote on Tue, 30 July 2013 20:06
>> Should be polypropylene unless you have a 1973 where someone reported it is polyethylene.
>>
>> Emery Store
>>
>> On Jul 30, 2013, at 8:41 PM, Peter Bailey <bugeye@internode.on.net> wrote:
>>
>>>
>>>
>>> Hi.
>>> I have a fine crack in my black tank under one of the holding straps what is recommended for glueing this?
>>> If I need to do a plastic weld does anyone know what plastic it is so I can use the correct plastic filler rod.
>>> Thanks in anticipation
>>> Peter Bailey
>>> from Ozy (Aussie)
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
> Maybe my memory is going but Emery I thought you corrected me a while back and said it was polyethylene and could be repaired with a milk bottle? At any rate melting the correct plastic into the crack with a large soldering iron will fix it but you need to take out the tank to repair it.
> --
> Roy Keen
> Minden,NV
> 76 X Glenbrook
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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Re: Black Tank [message #216365 is a reply to message #216334]

Wed, 31 July 2013 07:19

Galen

Messages: 146
Registered: November 2011
Location: New Virginia, IA

Karma: 0

Senior Member

Mine is a 78, and it is polyethylene. I can't explain why, as I haven't had the coach for the entire 35 years of its life so I don't know the whole story. Others on here have reported their tank repaired by plastic shops were polyethylene as well.

Here is a quick google on plastic identification:

http://www.boedeker.com/burntest.htm

Helps to have some plastic samples of a known type to test against.

Galen Briggs New Virginia, Iowa 1978 Palm Beach

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Re: Black Tank [message #216376 is a reply to message #216334]

Wed, 31 July 2013 08:45

Matt Colie

Messages: 8547
Registered: March 2007
Location: S.E. Michigan

Karma: 7

Senior Member

peter bailey wrote on Tue, 30 July 2013 22:41

Hi.
I have a fine crack in my black tank under one of the holding straps what is recommended for glueing this?
If I need to do a plastic weld does anyone know what plastic it is so I can use the correct plastic filler rod.
Thanks in anticipation
Peter Bailey
from Ozy (Aussie)

Peter,

As one that has dealt with a damaged black tank, I can tell you that it does not matter if it is Polyethylene or Polypropylene, you just can't glue it to a water proof seal. You can get things to seal to it if it is unloaded, but welding is your only good answer.

Both PE and PP need a cover gas to weld as they oxidize very easily at their welding temperatures. (That kills the cheap HF tools.)

I personally believe that your best bet will be to find a plastic fabricator to weld the crack. I can't begin to tell you where to start looking for one of those...

Good Luck

Matt

Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

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Re: Black Tank [message #216441 is a reply to message #216334]

Wed, 31 July 2013 19:22

gbarrow2

Messages: 765
Registered: February 2004
Location: Lake Almanor, Ca./ Red Bl...

Karma: 3

Senior Member

Peter,
Ten years ago my black tank had a leaking crack under/above one of the hold down/up straps just as you describe. I wasn't smart enough to get six opinions from three experts on the net.
So I went to the nearest RV supply store and bought a cheap black tank repair kit that consisted of sandpaper, fiberglass mat, and a tube of black goop (I think it was epoxy).

When the tank was empty and the crack was dry I removed one end of the strap and applied the patch. I didn't even have to jack up the coach- just raised the bags to max.

Since then I have driven the coach 100,000 miles and consequently filled and dumped the tank countless times. No leak yet.

I used the same type of kit to repair another GMCer's black tank. It held while I was delivering that coach across the US. As far as I know it is still holding.

Hope yours will be that simple and easy.

Gene Barrow
Lake Almanor, Ca.
1976 Palm Beach

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Re: Black Tank [message #216459 is a reply to message #216441]

Wed, 31 July 2013 21:11

roy1

Messages: 2126
Registered: July 2004
Location: Minden nevada

Karma: 6

Senior Member

gbarrow wrote on Wed, 31 July 2013 17:22

Peter,
Ten years ago my black tank had a leaking crack under/above one of the hold down/up straps just as you describe. I wasn't smart enough to get six opinions from three experts on the net.
So I went to the nearest RV supply store and bought a cheap black tank repair kit that consisted of sandpaper, fiberglass mat, and a tube of black goop (I think it was epoxy).

When the tank was empty and the crack was dry I removed one end of the strap and applied the patch. I didn't even have to jack up the coach- just raised the bags to max.

Since then I have driven the coach 100,000 miles and consequently filled and dumped the tank countless times. No leak yet.

I used the same type of kit to repair another GMCer's black tank. It held while I was delivering that coach across the US. As far as I know it is still holding.

Hope yours will be that simple and easy.

That can work with a minor repair although not with my luck I had a bad leak with a major crack caused from using body pads that were too tall. I managed to fix the tank with a propane torch in the thick area and a large soldering iron in the thinner area with a piece of polyethylene material.

Roy Keen Minden,NV 76 X Glenbrook

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Re: Black Tank [message #216499 is a reply to message #216441]

Thu, 01 August 2013 07:51

peter bailey

Messages: 367
Registered: March 2009
Location: Gawler, South Australia

Karma: 0

Senior Member

Gene,
I think I could be where you were at with your leak mine is just weeping not even dripping and I fear if I dont fix it it will get worse but I dont want to do something wrong like hitting it with a hot iron and making it worse, that is why I was looking for advice from others who had been there and done it so that when I do it from the correct advice it will be a no brainer repair.
Thanks all for your advice I will try to get a suitable adhesive available in Australia.,
Peter Bailey
from Ozy (Aussie)

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Re: [GMCnet] Black Tank [message #216516 is a reply to message #216499]

Thu, 01 August 2013 09:43

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

Peter,

If you decide you want to use 3M-5200 and you can't get it Downunder I'll send a tube back with Helen when she leaves here September
30th.

Regards,
Rob M.

-----Original Message-----
From: Peter Bailey

Gene,
I think I could be where you were at with your leak mine is just weeping not even dripping and I fear if I dont fix it it will get
worse but I dont want to do something wrong like hitting it with a hot iron and making it worse, that is why I was looking for
advice from others who had been there and done it so that when I do it from the correct advice it will be a no brainer repair.
Thanks all for your advice I will try to get a suitable adhesive available in Australia.,
Peter

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Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426

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Re: Black Tank [message #216518 is a reply to message #216499]

Thu, 01 August 2013 09:53

gbarrow2

Messages: 765
Registered: February 2004
Location: Lake Almanor, Ca./ Red Bl...

Karma: 3

Senior Member

Peter,
If you can't find repair kit locally; Adventure RV has several on their web site.
Good luck.

http://www.adventurerv.net/plastic-tank-repair-kit-p-540.html?utm_campaign=partsfeed_ppc&utm_medium=cpc&utm_source=Froogle&gclid=CJ_yiLy_3 LgCFWfhQgodK1AA2w

Gene Barrow
Lake Almanor, Ca.
1976 Palm Beach

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