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| Re: [GMCnet] Black tank basics [message #61491 is a reply to message #61486] |
Sat, 24 October 2009 18:29   |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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G'day Dennis,
I've put some comments in CAPS below.
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Dennis Sexton
Sent: Sunday, 25 October 2009 9:45 AM
To: gmclist@temp.gmcnet.org
Subject: [GMCnet] Black tank basics
I have never worked on the plumbing system of an RV and I need help and
advice on my plans for repairing the black tank on my 73, 23ft, with side
bath.
The tank inlets for the shower drain and the kitchen/bath sinks were welded
to the tank top, but both had developed cracks and weld failures. I have
removed these fittings and the tank has developed cracks in the web between
the inlets.
http://www.gmcmhphotos.com/photos/showphoto.php?photo=31250
http://www.gmcmhphotos.com/photos/showphoto.php?photo=31260
I have drizzled Loctite Plastic Adhesive (says it works for polypropelene)
into the cracks and am letting it dry. If it does not hold I was considering
gluing on a thin plastic patch or finding a plastic welder to make a repair.
EVEN IF THE LOCKTITE DOESN'T HOLD I'D SUGGEST MAKING UP A DOUBLER AND USING
3M-5200 TO GLUE IT IN PLACE. THAT WAY YOU KNOW ITS' FIXED AND WILL STAY
FIXED!
http://www.gmcmhphotos.com/photos/showphoto.php?photo=28384
A local RV dealer had rubber fittings which I understand are used for
attaching drain line to holding tanks so I plan to insert those in the
existing holes.
JOHN SHARPE USED THESE FITTINGS TO PLUMB IN THE NEW BLACK TANK IN HIS ROYALE
AND THEY WORKED FINE. HOWEVER, THE CONDITION OF THE TOP OF YOUR TANK WHERE
THEY WILL BE INSERTED DOESN'T LOOK TOO GOOD; IT MIGHT BE A GOOD IDEA TO GLUE
THEM IN WITH 3M-5200.
http://www.gmcmhphotos.com/photos/showphoto.php?photo=31259
http://www.gmcmhphotos.com/photos/showphoto.php?photo=31261
Plastic 1 1/2" pipe inserts into the rubber grommets and from there I
thought I would use rubber plumbing fittings from Lowe's to attach to the
existing drain pipe.
Does all this seem reasonable?
What do you do with the Thetford dump valve? Does this get replaced if I
eventually go to a macerator?
DEPENDS ON HOW YOU WANT TO PLUMB IN THE MACERATOR. I WOULD NOT DO AWAY WITH
THE 3" DRAIN, HOWEVER; HERE'S WHY! WHEN I WAS GETTING DOUBLE TROUBLE READY
TO PUT IN STORAGE I NEEDED TO DUMP THE BLACK TANK (OBVIOUSLY). WHEN I PULLED
THE HANDLE THE SHAFT THAT CONNECTS TO THE SLIDE VALVE IN THE 3" DUMP VALVE
PULLED OUT OF THE SLIDE COMPLETELY WITH THE VALVE OPEN. I LOOKED UP UNDER
THE COACH AND NOTED THAT THERE WAS A STREAM OF WASTE WATER SQUIRTING OUT OF
THE HOLE WHERE THE SHAFT WAS. I HAD TO USE THE 3" DUMP SYSTEM TO EMPTY THE
TANK.
http://www.gmcmhphotos.com/photos/showphoto.php?photo=31251
Thanks,
Dennis
--
Dennis Sexton
73 Painted Desert 230
Germantown, TN
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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: [GMCnet] Black tank basics [message #61513 is a reply to message #61491] |
Sat, 24 October 2009 20:57 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Rob,
Thank you for the input.
I have located 3M 5200 at the local Ace Hardware for $20 a tube. Also have a quote request in to local plastic welder.
As for the doubler on the top -- it would need to be larger in diameter than the inlets to allow the new rubber grommets to fit -- the groove is only as wide as the current tank thickness.
Regards,
Dennis
Dennis Sexton
73 GMC 230
Germantown, TN
G'day Dennis,
I've put some comments in CAPS below.
Regards,
ob Mueller
ydney, Australia
US '75 Avion-The Blue Streak TZE365V100428
SA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
rom: gmclist-bounces@temp.gmcnet.org
mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Dennis Sexton
ent: Sunday, 25 October 2009 9:45 AM
o: gmclist@temp.gmcnet.org
ubject: [GMCnet] Black tank basics
I have never worked on the plumbing system of an RV and I need help and
dvice on my plans for repairing the black tank on my 73, 23ft, with side
ath.
The tank inlets for the shower drain and the kitchen/bath sinks were welded
o the tank top, but both had developed cracks and weld failures. I have
emoved these fittings and the tank has developed cracks in the web between
he inlets.
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: Black tank basics [message #61514 is a reply to message #61486] |
Sat, 24 October 2009 21:14 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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I looked at your pictures. It looks definitely weldable. Several years ago I had mine welded in two different places. I have had no problems since then. It cost me $25.00 to have it done.
I recommend you try welding it.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Black tank basics [message #61515 is a reply to message #61508] |
Sat, 24 October 2009 21:10 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Dennis,
Gene and Dan have a point, however, a new tank is going to cost you two /
three hundred bucks by the time you get it to Memphis.
It's not going to cost you much in time, effort, or money to:
1) sand the top of the tank with very rough sand paper to remove all traces
of old glue
2) clean the surface with Acetone or MEK
3) fill the gap in the rubber fittings with 3M-5200 and install them in the
tank
4) remove any excess 3M-5200 that is around the fittings on the top of the
tank
5) make a doubler out of 1/8" - 1/4" thick plastic that extends about 2
inches beyond the outermost diameter of both holes leaving a gap 1/8" or so
around each rubber fitting
6) coat the bottom of the doubler completely with 3M-5200 and fit it over
the two fittings
7) fill the gap around the rubber fittings with 3M-5200
Since the repair is on top of the tank it will only be subject to waste
sloshing around and no real pressure.
The doublers I put on the bottom of my tank are plugging two cuts; one that
is 3" long and the other is 5" long. To make sure they got sealed I widened
them from thin cracks to about 1/8" wide or so in order to pump some 3M-5200
in them to fill them just before I fitted the doublers. To date they haven't
dripped one bit.
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Dan Gregg
Sent: Sunday, 25 October 2009 12:09 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Black tank basics
Dennis, I am with Gene, call Jim K for a price on a new one.
Dan
--
Dan & Teri Gregg
danandteri.blogspot.com
///Halon Automatic Fire Extinguishers
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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: [GMCnet] Black tank basics [message #61516 is a reply to message #61513] |
Sat, 24 October 2009 21:12 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Dennis,
This came in as I sent you the detailed version of my suggested fix!
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of dennisfsexton@aol.com
Sent: Sunday, 25 October 2009 12:57 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Black tank basics
Rob,
Thank you for the input.
I have located 3M 5200 at the local Ace Hardware for $20 a tube. Also have a
quote request in to local plastic welder.
As for the doubler on the top -- it would need to be larger in diameter than
the inlets to allow the new rubber grommets to fit -- the groove is only as
wide as the current tank thickness.
Regards,
Dennis
Dennis Sexton
73 GMC 230
Germantown, TN
G'day Dennis,
I've put some comments in CAPS below.
Regards,
ob Mueller
ydney, Australia
US '75 Avion-The Blue Streak TZE365V100428
SA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
rom: gmclist-bounces@temp.gmcnet.org
mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Dennis Sexton
ent: Sunday, 25 October 2009 9:45 AM
o: gmclist@temp.gmcnet.org
ubject: [GMCnet] Black tank basics
I have never worked on the plumbing system of an RV and I need help and
dvice on my plans for repairing the black tank on my 73, 23ft, with side
ath.
The tank inlets for the shower drain and the kitchen/bath sinks were welded
o the tank top, but both had developed cracks and weld failures. I have
emoved these fittings and the tank has developed cracks in the web between
he inlets.
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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: [GMCnet] Black tank basics [message #61528 is a reply to message #61514] |
Sun, 25 October 2009 03:29 |
Tin Gerbil
Messages: 236
Registered: October 2006
Location: Vancouver Island, B.C.
Karma: 0
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Senior Member |
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Ken;
I scarfed the old fittings off with a Skilsaw and had new ones spun
welled on with a router for the galley sink drain and the toilet drain.
The outlet fitting was cracked and I had it welded up. That was 2.5
years ago and I have no leaks. Total $40.
Gordon
Ken Burton wrote:
>
> I looked at your pictures. It looks definitely weldable. Several
> years ago I had mine welded in two different places. I have had no
> problems since then. It cost me $25.00 to have it done.
>
> I recommend you try welding it.
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Gordon
'74 Canyon Lands "Tin Gerbil"
Vancouver Island, B.C.
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| Re: [GMCnet] Black tank basics [message #61579 is a reply to message #61569] |
Sun, 25 October 2009 13:19 |
Tin Gerbil
Messages: 236
Registered: October 2006
Location: Vancouver Island, B.C.
Karma: 0
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Senior Member |
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Jerry;
I cut strips off the waist of my cotton "T" shirt and cemented a poly
pipe on to a tank with 3000 live salmon in it using RTV and a propane
torch to set it off at -10*F. In a panic, any fix that holds is a good
one. My retired high school chemistry teacher made up a good poly glue
using di-methyl something and acetone to dissolve poly chips 40 years
ago. Now 3M has an excellent poly glue available at Home Depot, why not
use it? The local sewer surgeon purchased a can last week, glued some
poly pipe to PVC, let it set overnight and then beat it to death with a
hammer. IT WORKS WELL!
Gordon
Jerry Holloway wrote:
> Use abs cement and fiberglas on black plastic tanks. I have used that combo
> to replace a fitting that was broken off completly.
>
> Jerry
> 77 E2
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Gordon
'74 Canyon Lands "Tin Gerbil"
Vancouver Island, B.C.
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| Re: [GMCnet] Black tank basics [message #61584 is a reply to message #61579] |
Sun, 25 October 2009 13:58 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Gordon,
Do you have the name or number of the 3M product your plumber used?
I looked for 8005 but no one seems to stock it locally.
Thanks,
Dennis
Dennis Sexton
73 GMC
Germantown, TN
USA
-----Original Message-----
From: The Tin Gerbil, Ad Nauseum <wizwing@telus.net>
To: gmclist@temp.gmcnet.org
Sent: Sun, Oct 25, 2009 1:19 pm
Subject: Re: [GMCnet] Black tank basics
Jerry;
cut strips off the waist of my cotton "T" shirt and cemented a poly
ipe on to a tank with 3000 live salmon in it using RTV and a propane
orch to set it off at -10*F. In a panic, any fix that holds is a good
ne. My retired high school chemistry teacher made up a good poly glue
sing di-methyl something and acetone to dissolve poly chips 40 years
go. Now 3M has an excellent poly glue available at Home Depot, why not
se it? The local sewer surgeon purchased a can last week, glued some
oly pipe to PVC, let it set overnight and then beat it to death with a
ammer. IT WORKS WELL!
ordon
Jerry Holloway wrote:
Use abs cement and fiberglas on black plastic tanks. I have used that combo
to replace a fitting that was broken off completly.
Jerry
77 E2
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MCnet mailing list
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_______________________________________________
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Black tank basics [message #61598 is a reply to message #61574] |
Sun, 25 October 2009 16:01 |
Tin Gerbil
Messages: 236
Registered: October 2006
Location: Vancouver Island, B.C.
Karma: 0
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Senior Member |
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Roger;
Isn't that the standard method on all GMC's?
Behind this rubber coupling I have a 4" dia. 12" long, expansion joint
one foot back from the tank. It is pulled out half it's travel, so in
the event of a minor rear end collision, the dump valve, tank and pipe
will not be crushed. It eliminates all the pressure on the welded
flange on the tank. This is a $9.00 joint they use in the vent stack of
2+ floor buildings. It allows my solid ABS which turns and runs parallel
to the bumper, to rotate down toward the drain. It is held up
completely out of the way during travel by two bungie cords. We have to
be very careful with the design of our sewer pipe because we have a
sharp drop on and off the ferry ramp every time we leave the island. I
think I will improve the system that holds it up will some SS chain.
Gordon
Roger Black wrote:
> Get the fitting solid then go with a flexible rubber coupling from the
> tank to piping. Works for me.
>
> Roger Black
> Burns, TN
> 77 Birchaven SB
>
>
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
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_______________________________________________
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Gordon
'74 Canyon Lands "Tin Gerbil"
Vancouver Island, B.C.
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| Re: Black tank basics [message #61609 is a reply to message #61486] |
Sun, 25 October 2009 17:10 |
rgleas
Messages: 48
Registered: May 2009
Location: Tulsa, Ok.
Karma: 0
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Member |
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I had a crack under one of the braces when I brought my coach along with the fresh water tank had cracked at a seam.
I brought a new tank from Jim K. it was a very easy replacement the only difficult part was laying out the holes in the top of the tank. I hate dealing with the black wate so for me I just did not want to have to fix this problem again.
I then welded both the fresh water and the black water tanks figuring I would have a spare if anyone needed it. The fresh water tank is still full of water since I wanted to test the weld. The black water tank cracked back open along the original crack.
Bottom line I do not regret purchasing a new tank.
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