Home » Public Forums » GMCnet » Replacing black tank on a rear bath Birchaven
| Replacing black tank on a rear bath Birchaven [message #212429] |
Wed, 26 June 2013 22:29  |
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Richard RV
Messages: 631
Registered: July 2012
Location: Full-timer for 12 years, ...
Karma: -17
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Hi. My black tank has given up the ghost and I'm getting set to install the replacement I bought from Applied. The holding tank configuration that Coachmen came up with for the rear bath Birchaven was innovative, and by that I mean odd. I wasn't sure if a PO had reconfigured things when he put in the macerator, but from perusing the photo site, nope, it's a Coachmen original.
I would appreciate some input, warnings, and hell, encouragement couldn't hurt! I'm doing the work in Phoenix on gravel and it's supposed to be up around 115F this weekend, so the encouragement may be the most important part. 
My questions:
- is it necessary to disassemble the toilet riser box to replace the black tank? I read on the forum that people used a homebrew wood "wrench" to unscrew the toilet flange, but as best as I can see (trying to see the vent line from the small gap in the side of the riser box/vanity and floor) the vent line appears to be glued the whole way and takes some tight bends as it snakes around the poop chute inside the riser box. I ended up cutting the waste and vent lines flush with the top of the old tank to remove the tank, and would prefer to not have to open up the riser box if it's avoidable.
- The waste and vent lines are not perpendicular/plumb - they're tilted with the bottoms closer to the front of the coach, ~5-7 degrees. If both waste and vent tails can be removed without taking apart the riser box, will direct replacement (reinstalling the lines tilted) create problems with the rubber grommet tank seal?
- Mike Miller had posted a couple of pictures of his reconfiguration in progress, and mentioned he'd post pictures of the completed installation when he got a round tuit. Mike, if you're reading this, are those after images posted? I couldn't find them and I would like to see more.
- I'm going to be rotating the new tank so the outlet is on the driver's side which will consolidate a lot of the plumbing, allow the grey tank to flush out the black tank, and shift the black tank a couple or few inches towards the drivers side. I'm going to be redoing my exhaust, against my wallet's better judgement, and I'm wondering if shifting the tank over will improve my chances of getting a single rear muffler installed. Has anyone installed a single rear muffler in a 23' rear bath Birchaven?
Thanks in advance for any pointers.
Richard
'77 Birchaven TZE...777;
'76 Palm Beach under construction;
‘76 Edgemont waiting its turn
[Updated on: Thu, 27 June 2013 00:01] Report message to a moderator |
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| Re: Replacing black tank on a rear bath Birchaven [message #212465 is a reply to message #212429] |
Thu, 27 June 2013 08:06  |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Richard,
Not much new info from me -- but here is a link to a 77 black tank photo album..
http://www.gmcmhphotos.com/photos/g4079-birchaven-holding-tank.html
When lowering the black tank on my 73, I used a 20 inch square of plywood and a small floor jack to hold it in place while I removed all the mountings and then let it drop slowly. While it is not heavy it is awkward working under the coach.
Ken H has a photo album on macerator install on a Birch -- I believe he has two macerators on his coach.
Good luck -- "at least it is a dry heat" Phoenix.
Dennis
| Richard V. wrote on Wed, 26 June 2013 22:29 |
Hi. My black tank has given up the ghost and I'm getting set to install the replacement I bought from Applied. The holding tank configuration that Coachmen came up with for the rear bath Birchaven was innovative, and by that I mean odd. I wasn't sure if a PO had reconfigured things when he put in the macerator, but from perusing the photo site, nope, it's a Coachmen original.
I would appreciate some input, warnings, and hell, encouragement couldn't hurt! I'm doing the work in Phoenix on gravel and it's supposed to be up around 115F this weekend, so the encouragement may be the most important part.
My questions:
- is it necessary to disassemble the toilet riser box to replace the black tank? I read on the forum that people used a homebrew wood "wrench" to unscrew the toilet flange, but as best as I can see (trying to see the vent line from the small gap in the side of the riser box/vanity and floor) the vent line appears to be glued the whole way and takes some tight bends as it snakes around the poop chute inside the riser box. I ended up cutting the waste and vent lines flush with the top of the old tank to remove the tank, and would prefer to not have to open up the riser box if it's avoidable.
- The waste and vent lines are not perpendicular/plumb - they're tilted with the bottoms closer to the front of the coach, ~5-7 degrees. If both waste and vent tails can be removed without taking apart the riser box, will direct replacement (reinstalling the lines tilted) create problems with the rubber grommet tank seal?
- Mike Miller had posted a couple of pictures of his reconfiguration in progress, and mentioned he'd post pictures of the completed installation when he got a round tuit. Mike, if you're reading this, are those after images posted? I couldn't find them and I would like to see more.
- I'm going to be rotating the new tank so the outlet is on the driver's side which will consolidate a lot of the plumbing, allow the grey tank to flush out the black tank, and shift the black tank a couple or few inches towards the drivers side. I'm going to be redoing my exhaust, against my wallet's better judgement, and I'm wondering if shifting the tank over will improve my chances of getting a single rear muffler installed. Has anyone installed a single rear muffler in a 23' rear bath Birchaven?
Thanks in advance for any pointers.
Richard
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: Replacing black tank on a rear bath Birchaven [message #212467 is a reply to message #212465] |
Thu, 27 June 2013 08:11 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Richard,
Please note -- I did not take advantage of the opportunity to solicit sales for GMC round tuits -- but thank you for the opening 
http://www.gmcmhphotos.com/photos/round-tuits/p48440-gmcstoredtoolong.html
Dennis
| Dennis S wrote on Thu, 27 June 2013 08:06 |
Richard,
Not much new info from me -- but here is a link to a 77 black tank photo album..
http://www.gmcmhphotos.com/photos/g4079-birchaven-holding-tank.html
When lowering the black tank on my 73, I used a 20 inch square of plywood and a small floor jack to hold it in place while I removed all the mountings and then let it drop slowly. While it is not heavy it is awkward working under the coach.
Ken H has a photo album on macerator install on a Birch -- I believe he has two macerators on his coach.
Good luck -- "at least it is a dry heat" Phoenix.
Dennis
| Richard V. wrote on Wed, 26 June 2013 22:29 |
Hi. My black tank has given up the ghost and I'm getting set to install the replacement I bought from Applied. The holding tank configuration that Coachmen came up with for the rear bath Birchaven was innovative, and by that I mean odd. I wasn't sure if a PO had reconfigured things when he put in the macerator, but from perusing the photo site, nope, it's a Coachmen original.
I would appreciate some input, warnings, and hell, encouragement couldn't hurt! I'm doing the work in Phoenix on gravel and it's supposed to be up around 115F this weekend, so the encouragement may be the most important part.
My questions:
- is it necessary to disassemble the toilet riser box to replace the black tank? I read on the forum that people used a homebrew wood "wrench" to unscrew the toilet flange, but as best as I can see (trying to see the vent line from the small gap in the side of the riser box/vanity and floor) the vent line appears to be glued the whole way and takes some tight bends as it snakes around the poop chute inside the riser box. I ended up cutting the waste and vent lines flush with the top of the old tank to remove the tank, and would prefer to not have to open up the riser box if it's avoidable.
- The waste and vent lines are not perpendicular/plumb - they're tilted with the bottoms closer to the front of the coach, ~5-7 degrees. If both waste and vent tails can be removed without taking apart the riser box, will direct replacement (reinstalling the lines tilted) create problems with the rubber grommet tank seal?
- Mike Miller had posted a couple of pictures of his reconfiguration in progress, and mentioned he'd post pictures of the completed installation when he got a round tuit. Mike, if you're reading this, are those after images posted? I couldn't find them and I would like to see more.
- I'm going to be rotating the new tank so the outlet is on the driver's side which will consolidate a lot of the plumbing, allow the grey tank to flush out the black tank, and shift the black tank a couple or few inches towards the drivers side. I'm going to be redoing my exhaust, against my wallet's better judgement, and I'm wondering if shifting the tank over will improve my chances of getting a single rear muffler installed. Has anyone installed a single rear muffler in a 23' rear bath Birchaven?
Thanks in advance for any pointers.
Richard
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Dennis S
73 Painted Desert 230
Memphis TN Metro
[Updated on: Thu, 27 June 2013 08:12] Report message to a moderator |
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| Re: Replacing black tank on a rear bath Birchaven [message #212494 is a reply to message #212429] |
Thu, 27 June 2013 10:48 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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Senior Member |
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| Richard V. wrote on Wed, 26 June 2013 20:29 |
...
- Mike Miller had posted a couple of pictures of his reconfiguration in progress, and mentioned he'd post pictures of the completed installation when he got a round tuit. Mike, if you're reading this, are those after images posted? I couldn't find them and I would like to see more. ...
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The final product isn't much different than the picture I had already posted. I am not happy with how low it is, as it is very easy to drag and as the lowest piping is the smaller stuff, it doesn't take much to break. But I think it is about the best I can do without replacing the tank(s). On the upside, it is fairly easy to reach to replace the broken parts. All the "extra" valves allows most parts to be replaced with "stuff" still in the tank.
<http://www.gmcmhphotos.com/photos/brichaven-rear-bath-macerator/p40076-rear-bath-macerator-in.html>
The differences are that the pump is electrically connected and all large gate valve handles are to the rear. I had to drill a hole in the frame for the discharge hose of the macerator. It ran close to the Onan exhaust pipe so I used conduit pipe in that section. I'll look for a picture of the discharge hose routing or take another picture.
When replacing the tank, if you can put the output on the side rather than under the bumper... DO SO!
With a 23 foot coach and two tanks, there isn't much room to work with, but when replacing tanks you have more options. Seems to me, what would work well is: One valve at the output of the gray tank, feeding to a Tee at the "side mounted" output of the black tank. Another gate valve just as the plumbing exits under the frame. Finish with a Tee with the macerator mounted in the center right behind the tank, and a 3 inch dump in the OEM location. (Both with gate valves.)
For power I tapped into "house" power at the circuit breaker under the Onan. The switch, mounted in the bumper bracket, supplies a ground to the pump. (Switched ground.) It works but I might change this later.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: Replacing black tank on a rear bath Birchaven [message #212496 is a reply to message #212465] |
Thu, 27 June 2013 10:53 |
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Richard RV
Messages: 631
Registered: July 2012
Location: Full-timer for 12 years, ...
Karma: -17
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Senior Member |
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Thanks, Dennis. I took a look at your pictures, and they were of the early stages of your tank replacement. Your waste line in the picture was new, and I'm assuming that it was threaded at both ends, but the vent line was the old one and you cut that to get it out. Do you recall if the vent stub threaded into the upper fitting inside the toilet riser box, or did you have to glue on a coupling?
I love the Round Tuit! You're selling them? I'd take some...one of these days! No seriously, what's the deal with them, and do you have them in 23' rear bath Birchavens? I bought an GMC enameled metal stick pin from Ramona Sirum at a rally last year, and I was proud as a peacock wearing it until someone pointed out that I have a 23' and the pin is a 26'!
Richard
'77 Birchaven TZE...777;
'76 Palm Beach under construction;
‘76 Edgemont waiting its turn
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| Re: Replacing black tank on a rear bath Birchaven [message #212498 is a reply to message #212471] |
Thu, 27 June 2013 10:57 |
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Richard RV
Messages: 631
Registered: July 2012
Location: Full-timer for 12 years, ...
Karma: -17
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Senior Member |
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Hi, Miguel. I took your advice and JimK was so fast with the shipping that the tank was delivered last week! So I have the tank, it's just a question of what was initially going to be a simple black tank goop repair, which morphed into a tank replacement, will morph again into opening up the toilet riser box to rework the fittings.
Richard
'77 Birchaven TZE...777;
'76 Palm Beach under construction;
‘76 Edgemont waiting its turn
[Updated on: Thu, 27 June 2013 10:58] Report message to a moderator |
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| Re: Replacing black tank on a rear bath Birchaven [message #212501 is a reply to message #212494] |
Thu, 27 June 2013 11:13 |
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Richard RV
Messages: 631
Registered: July 2012
Location: Full-timer for 12 years, ...
Karma: -17
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Senior Member |
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Thanks for the advice, Mike. I appreciate the "what I'd do next time" comments as I really don't want to do this a next time. I don't even want to do it this time!
I noticed the wide flat steel tank guard that is bent up at the ends and bolted to the diagonal bracing of the rear clip. I thought mine was a homebrew as the bolt holes were nasty burned holes in the frame. It also acted as a very effective "impact force redistribution system" - wherever along it's length the tank guard took an impact it very considerately imparted some of the impact to the lowest part of the OEM tank it was meant to protect. And it made a reasonable facsimile of a road grader blade.
Please elaborate a bit on what you wrote:
"Seems to me, what would work well is: One valve at the output of the gray tank, feeding to a Tee at the "side mounted" output of the black tank. Another gate valve just as the plumbing exits under the frame. Finish with a Tee with the macerator mounted in the center right behind the tank, and a 3 inch dump in the OEM location. (Both with gate valves.)"
When you say as the plumbing exits under the frame, you mean straight back and not out the side, right?
What's the purpose of having the second gate valve at the back? Is that to shut off the flow to the macerator? I can't quite picture what you mean.
Thanks again for the assistance.
Richard
'77 Birchaven TZE...777;
'76 Palm Beach under construction;
‘76 Edgemont waiting its turn
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