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| [GMCnet] black tank [message #165478] |
Thu, 05 April 2012 15:51  |
Brian Waddell
Messages: 409
Registered: March 2010
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my black tank valve was a thetford which was cream colored....it leaked badly and was sealed on with silicone like caulking....with great difficulty I got the inner part of that valve off....the tank itself looks not too bad in regards to the outlet where that valve bolts to...now my guestion....How to I attach a viterra valve which is black of which I have including the macerator port, to the black tank? ....also which type of glue do I use ? is this tank abs or pvc or what? any help much appreciated.....brian 77 elegansa 455
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| Re: [GMCnet] black tank [message #165489 is a reply to message #165478] |
Thu, 05 April 2012 18:12  |
Chr$
Messages: 2690
Registered: January 2004
Location: Scottsdale, AZ
Karma: 1
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Tank is Polyethylene (PE). You cannot glue it to anything. The new Valterra is ABS. You will need to get an adapter, or make one, or replace the tank with a new one that has a 3" round outlet that is easy to connect a rubber coupling to it and the Valve.
The threads on the tank are probably toast. I tried filling them with new PE (welded) and re-tapping them with both Helicoils and with nuts on the back. That leaked either way and with both.
I tried to replace my flange but it eventually leaked as the tank is not really smooth at that location nor conducive to good plastic welding. It leaks where it is welded to the tank, probably cracked at the weld because tank is too brittle.
I will buy a new one soon myself. Save yourself the trouble. Do the same. Jim K has them, you drop your tank, get the measurements of all the ports, then the MFG spin-welds new fittings onto the new one to match your locations.
Oh, New RTV or rubber gaskets won't last due to the leaks actually being at the welds.
-Chr$: Perpetual SmartAss
Scottsdale, AZ
77 Ex-Kingsley 455 SOLD!
2010 Nomad 24 Ft TT 390W PV W/MPPT, EV4010 and custom cargo door.
Photosite: Chrisc GMC:"It has Begun" TT: "The Other Woman"
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| Re: [GMCnet] black tank [message #165492 is a reply to message #165487] |
Thu, 05 April 2012 18:42 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| Brian Waddell wrote on Thu, 05 April 2012 18:39 |
No....not like those that I can see....those people appear to be using part of a thetford valve (whitish colored)...and then adapting a thetford to it.....I am trying to adapt my thetford valve (black colored) directly to the tank.....unless I missed somthing there, when I looked before ,they are using part of viterra valve...thanks...brian
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Brian,
All Thetford valves are white.
If it is black, it is something else.
Most available are Valterra. There are also Grentec and Anonda and others.
Thetford is not a type of valve, it is a manufacturer. The type of valve is slide gate waste valve.
The white block on the tank is welded to the tank. There are four screws holding the original Thetford valve to that block. The mounting screw locations of a Valterra valve are different than the Thetford valve. If the valve was leaking at the tank, the screw holes in the white block can be repaired by using spiral inserts (Helicoil) in the top two and through bolting the bottom two and replacing all the fasteners with stainless. New face seals come in the rebuild kit.
No matter what you do, you will have to arrange it so it fits between the tank and the floor frame directly aft. If you try to put an adapter between the white flange and the new valve, there will be space issues.
Replacement Thetford valve (JimK) are still available and rebuild kits for all but the stainless one side version are still available from Thetford.
The parts of the dump piping are all ABS, but with care and cleaning can be glued to PVC DWV pipe fittings. The tank is polyethylene. There are some special adhesives that can be used, but pretty much has to be welded.
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: [GMCnet] black tank [message #165494 is a reply to message #165489] |
Thu, 05 April 2012 18:54 |
Brian Waddell
Messages: 409
Registered: March 2010
Karma: -4
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Senior Member |
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this is not what I wanted to hear.....being that the tank is in good shape and the problem is with adapting a valterra valve to the original tank outlet....I am surprised that the most reasonable solution would be to get a new tank with the required adapters attached...brian
> To: gmclist@temp.gmcnet.org
> From: cchoffataz@yahoo.com
> Date: Thu, 5 Apr 2012 18:12:59 -0500
> Subject: Re: [GMCnet] black tank
>
>
>
> Tank is Polyethylene (PE). You cannot glue it to anything. The new Valterra is ABS. You will need to get an adapter, or make one, or replace the tank with a new one that has a 3" round outlet that is easy to connect a rubber coupling to it and the Valve.
>
> The threads on the tank are probably toast. I tried filling them with new PE (welded) and re-tapping them with both Helicoils and with nuts on the back. That leaked either way and with both.
>
> I tried to replace my flange but it eventually leaked as the tank is not really smooth at that location nor conducive to good plastic welding. It leaks where it is welded to the tank, probably cracked at the weld because tank is too brittle.
>
> I will buy a new one soon myself. Save yourself the trouble. Do the same. Jim K has them, you drop your tank, get the measurements of all the ports, then the MFG spin-welds new fittings onto the new one to match your locations.
>
> Oh, New RTV or rubber gaskets won't last due to the leaks actually being at the welds.
> --
> -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"
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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| Re: [GMCnet] black tank [message #165495 is a reply to message #165492] |
Thu, 05 April 2012 19:13 |
Brian Waddell
Messages: 409
Registered: March 2010
Karma: -4
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Senior Member |
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sorry I got my terminology wrong.....black valve is valterra....white valve is thetford....on mine the base or inside part of the thetford is bolted to the tank and then glue or silicon was used to seal it....this block was never part of the tank but half of the thetford valve of which the slide part of the valve screws to....anyway I was able to remove all thetford parts ....now I have a tank with a round opening and 4 bolt holes in a square pattern around the opening....so how do I attach a viterra valve to this?.....brian
> To: gmclist@temp.gmcnet.org
> From: matt7323tze@gmail.com
> Date: Thu, 5 Apr 2012 18:42:48 -0500
> Subject: Re: [GMCnet] black tank
>
>
>
> Brian Waddell wrote on Thu, 05 April 2012 18:39
> > No....not like those that I can see....those people appear to be using part of a thetford valve (whitish colored)...and then adapting a thetford to it.....I am trying to adapt my thetford valve (black colored) directly to the tank.....unless I missed somthing there, when I looked before ,they are using part of viterra valve...thanks...brian
>
> Brian,
>
> All Thetford valves are white.
> If it is black, it is something else.
> Most available are Valterra. There are also Grentec and Anonda and others.
> Thetford is not a type of valve, it is a manufacturer. The type of valve is slide gate waste valve.
>
> The white block on the tank is welded to the tank. There are four screws holding the original Thetford valve to that block. The mounting screw locations of a Valterra valve are different than the Thetford valve. If the valve was leaking at the tank, the screw holes in the white block can be repaired by using spiral inserts (Helicoil) in the top two and through bolting the bottom two and replacing all the fasteners with stainless. New face seals come in the rebuild kit.
>
> No matter what you do, you will have to arrange it so it fits between the tank and the floor frame directly aft. If you try to put an adapter between the white flange and the new valve, there will be space issues.
>
> Replacement Thetford valve (JimK) are still available and rebuild kits for all but the stainless one side version are still available from Thetford.
>
> The parts of the dump piping are all ABS, but with care and cleaning can be glued to PVC DWV pipe fittings. The tank is polyethylene. There are some special adhesives that can be used, but pretty much has to be welded.
>
> 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
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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| Re: [GMCnet] black tank [message #165496 is a reply to message #165494] |
Thu, 05 April 2012 19:25 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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[quote title=Brian Waddell wrote on Thu, 05 April 2012 16:54]
this is not what I wanted to hear.....being that the tank is in good shape and the problem is with adapting a valterra valve to the original tank outlet....I am surprised that the most reasonable solution would be to get a new tank with the required adapters attached...brian
>
> I had to deal with that last year as the mounting screw flanges that hold the thedford valve to the tank got broken off dealing with body pads that were too thick. What I did was grind the 4 mounting holes off . I went to Home Depot and got a rubber pipe adaptor with a metal shield . I'm not sure of the size probibly 4" to 3". Had to add a little rubber spacer to the tank side as it wasn't quite 4". I also had to open up the removible frame support so it fit thru. Connected the Valterra valve and adjusted dump pipe length as needed. Pain in the *** but it worked.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] black tank [message #165501 is a reply to message #165495] |
Thu, 05 April 2012 20:44 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Brian,
At one time someone produced an adapter -- a short coupling that had Thetford bolt hole spacing on one end and Valterra on the other. In my searching I have not found one. I considered all manner of custom adapters -- but all had draw backs -- and space was critical to the final install.
So -- I just bought a new Thetford valve to attach to the black tank and used a rubber sweeping Tee to install the macerator. The other end of the Tee accepted the Valterra which I have for alternative dumping.
Here is my photo album...
http://www.gmcmhphotos.com/photos/showgallery.php?cat=5767
Dennis
| Brian Waddell wrote on Thu, 05 April 2012 19:13 |
sorry I got my terminology wrong.....black valve is valterra....white valve is thetford....on mine the base or inside part of the thetford is bolted to the tank and then glue or silicon was used to seal it....this block was never part of the tank but half of the thetford valve of which the slide part of the valve screws to....anyway I was able to remove all thetford parts ....now I have a tank with a round opening and 4 bolt holes in a square pattern around the opening....so how do I attach a viterra valve to this?.....brian
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] black tank [message #165578 is a reply to message #165478] |
Fri, 06 April 2012 17:38 |
Chr$
Messages: 2690
Registered: January 2004
Location: Scottsdale, AZ
Karma: 1
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Senior Member |
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I found one of those adapters. But the Flange already welded to the tank was the problem. You can try to fix it, but given what I and others have found, it is a fools errand and a messy one at that.
Just my opinion.
I'm getting a new tank so I no longer have to worry about it.
-Chr$: Perpetual SmartAss
Scottsdale, AZ
77 Ex-Kingsley 455 SOLD!
2010 Nomad 24 Ft TT 390W PV W/MPPT, EV4010 and custom cargo door.
Photosite: Chrisc GMC:"It has Begun" TT: "The Other Woman"
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| Re: [GMCnet] black tank [message #165581 is a reply to message #165578] |
Fri, 06 April 2012 19:08 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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| Chr$ wrote on Fri, 06 April 2012 15:38 |
I found one of those adapters. But the Flange already welded to the tank was the problem. You can try to fix it, but given what I and others have found, it is a fools errand and a messy one at that.
Just my opinion.
I'm getting a new tank so I no longer have to worry about it.
|
A new tank is a good thing but I just had to see if I could adapt the Valterra to the tank before I parted with more of my hard earned cash. I don't have to punch a clock any more so I have a little more time to devote then a hard working guy like you.
If you remove the webbing from the 4 mounting holes it will leave enough meat to fasten the adapter but you will need to increase the size of the flange a little. I used some thin rubber to get it too the correct diameter, it doesn't take much. If you just clamp the adapter on it you will not get a leak free connection on the 3" side as it won't be an even clamp.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] black tank [message #166323 is a reply to message #165489] |
Sat, 14 April 2012 11:40 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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Actually the original holding tanks are polybutylene (at least that is what the manuals say).
But you are correct that glue doesn't hold to them. However a good plastic welder can usually fix them and even weld a different outlet onto them to fit the Valterra style valve.
I however did as you suggest and replaced the tank a few years back. The plastic tank does get brittle over years and it's often best to just replace it.
Emery Stora
On Apr 5, 2012, at 5:12 PM, Chris Choffat <cchoffataz@yahoo.com> wrote:
>
>
> Tank is Polyethylene (PE). You cannot glue it to anything. The new Valterra is ABS. You will need to get an adapter, or make one, or replace the tank with a new one that has a 3" round outlet that is easy to connect a rubber coupling to it and the Valve.
>
> The threads on the tank are probably toast. I tried filling them with new PE (welded) and re-tapping them with both Helicoils and with nuts on the back. That leaked either way and with both.
>
> I tried to replace my flange but it eventually leaked as the tank is not really smooth at that location nor conducive to good plastic welding. It leaks where it is welded to the tank, probably cracked at the weld because tank is too brittle.
>
> I will buy a new one soon myself. Save yourself the trouble. Do the same. Jim K has them, you drop your tank, get the measurements of all the ports, then the MFG spin-welds new fittings onto the new one to match your locations.
>
> Oh, New RTV or rubber gaskets won't last due to the leaks actually being at the welds.
> --
> -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"
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
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| Re: [GMCnet] black tank [message #166332 is a reply to message #165478] |
Sat, 14 April 2012 13:20 |
Galen
Messages: 146
Registered: November 2011
Location: New Virginia, IA
Karma: 0
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Senior Member |
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According to x7525 page 24L-3, its says its polypropylene. Were there different plastics used in different years? Mine is a '78...I thought it was polyethylene, but I'm no plastics expert, just based on my amateur test with the scraps from removing the sending unit. My tank is in good shape, except the sending unit hole is bad. I was thinking of trying to block it off, but I seems I've read at least three different ideas on the plastic used, PE, PP and PB.
It sounds like my tank is the same as Brian's, with no separate flange on the tank (just molded flat), or that the Thetford valve mounts flush on the tank to the embedded threaded metal "nuts" or whatever.
Galen Briggs
New Virginia, Iowa
1978 Palm Beach
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| Re: [GMCnet] black tank [message #166334 is a reply to message #166332] |
Sat, 14 April 2012 13:56 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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You are correct. I should have said polypropylene. I don't know why I said polybutylene as I know better.
Emery Stora
On Apr 14, 2012, at 12:20 PM, Galen Briggs <gpbriggs@iowatelecom.net> wrote:
>
>
> According to x7525 page 24L-3, its says its polypropylene. Were there different plastics used in different years? Mine is a '78...I thought it was polyethylene, but I'm no plastics expert, just based on my amateur test with the scraps from removing the sending unit. My tank is in good shape, except the sending unit hole is bad. I was thinking of trying to block it off, but I seems I've read at least three different ideas on the plastic used, PE, PP and PB.
>
> It sounds like my tank is the same as Brian's, with no separate flange on the tank (just molded flat), or that the Thetford valve mounts flush on the tank to the embedded threaded metal "nuts" or whatever.
> --
> Galen Briggs
> New Virginia, Iowa
> 1978 Palm Beach
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