Holding Tank Capacity

R

richard waters

New member
Feb 8, 1999
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> OEM holding tank on the GMC is 40 Gallons capacity.
> J.R. Wright
>
>
> > A friend of mine is contemplating replacing his decrepit old holding tank
> > with a new one. Ardemco has a tank for the GMC similar to the original;
> > capacity is listed as 30 gallons, about the same as OEM.
> >
> > He is speculating that more capacity would be very desirable and wonders
> > about using a deeper tank. One that is 1 1/2" deeper would increase
> > capacity to over 40 gallons.
> > Glenn
> > 78 Kingsley II

John,
Are you sure of the holding tank capacity? According to the
owner's manual for my 1976 GMC Motorhome the Holding Tank
has a capacity of 32 gallons. The Living Area Water Tank has a
capacity of 40 Gallons.

I'm pretty sure of the fact that the water tank holds more then the
holding tank. The reason I know that is because back in December
I took my neighbor up to Sandusky to pick up his 1973 23' Canyon
Lands from Cinnabar after having its engine overhauled.

To make a long story short we left with full water and hot water tanks
and an empty holding tank. My neighbor used the toilet in the way up
and managed to leave the pump and sink faucet on. When we arrived
in Sandusky, the water tank was empty and we had about 2" of water
on the floor of the bathroom. So I'm real sure that the 40 gallon water
tank holds more then the holding tank. At least that was the case in
my OEM coach.

I was real lucky that the holding tank contained only water from the water
tank. It would have been a real mess if that had not been the case :(

Richard Waters '76 PB, Troy, MI
 
My apologies you are correct.
- --
J.R. Wright
GMC GreatLakers
77 Eleganza II
Michigan

>
> > OEM holding tank on the GMC is 40 Gallons capacity.
> > J.R. Wright
> >
> >
> > > A friend of mine is contemplating replacing his decrepit old holding tank
> > > with a new one. Ardemco has a tank for the GMC similar to the original;
> > > capacity is listed as 30 gallons, about the same as OEM.
> > >
> > > He is speculating that more capacity would be very desirable and wonders
> > > about using a deeper tank. One that is 1 1/2" deeper would increase
> > > capacity to over 40 gallons.
> > > Glenn
> > > 78 Kingsley II
>
> John,
> Are you sure of the holding tank capacity? According to the
> owner's manual for my 1976 GMC Motorhome the Holding Tank
> has a capacity of 32 gallons. The Living Area Water Tank has a
> capacity of 40 Gallons.
>
> I'm pretty sure of the fact that the water tank holds more then the
> holding tank. The reason I know that is because back in December
> I took my neighbor up to Sandusky to pick up his 1973 23' Canyon
> Lands from Cinnabar after having its engine overhauled.
>
> To make a long story short we left with full water and hot water tanks
> and an empty holding tank. My neighbor used the toilet in the way up
> and managed to leave the pump and sink faucet on. When we arrived
> in Sandusky, the water tank was empty and we had about 2" of water
> on the floor of the bathroom. So I'm real sure that the 40 gallon water
> tank holds more then the holding tank. At least that was the case in
> my OEM coach.
>
> I was real lucky that the holding tank contained only water from the water
> tank. It would have been a real mess if that had not been the case :(
>
> Richard Waters '76 PB, Troy, MI
 
John,
This is about the first time that I have been
right about anything regarding the GMC. I guess
I've learned something during the past 18 months.
Richard

> My apologies you are correct.
> --
> J.R. Wright
> GMC GreatLakers
> 77 Eleganza II
> Michigan

> >
> > > OEM holding tank on the GMC is 40 Gallons capacity.
> > > J.R. Wright
>
> >
> > John,
> > Are you sure of the holding tank capacity? According to the
> > owner's manual for my 1976 GMC Motorhome the Holding Tank
> > has a capacity of 32 gallons. The Living Area Water Tank has a
> > capacity of 40 Gallons.
> >
> >I
 
Holding tank capacity is 32 or 33 gallons thru 1977 and nominally
40 gallons in 1978. Cinnabar has the 40 gallon tanks as replacements
for all units. They don't really hold 40 because they use a rubber insert
that requires the pipes to extend down into the tank a short distance.
Wes is full of crap when he tells you how easy the installation is.
However, after the installation is done, it is a tremendous improvement.
Gary Kosier
- ----- Original Message -----
From: Richard Waters
To:
Sent: Monday, February 07, 2000 1:17 PM
Subject: Re: GMC: Holding Tank Capacity

> > OEM holding tank on the GMC is 40 Gallons capacity.
> > J.R. Wright
> >
> >
> > > A friend of mine is contemplating replacing his decrepit old holding
tank
> > > with a new one. Ardemco has a tank for the GMC similar to the
original;
> > > capacity is listed as 30 gallons, about the same as OEM.
> > >
> > > He is speculating that more capacity would be very desirable and
wonders
> > > about using a deeper tank. One that is 1 1/2" deeper would increase
> > > capacity to over 40 gallons.
> > > Glenn
> > > 78 Kingsley II
>
> John,
> Are you sure of the holding tank capacity? According to the
> owner's manual for my 1976 GMC Motorhome the Holding Tank
> has a capacity of 32 gallons. The Living Area Water Tank has a
> capacity of 40 Gallons.
>
> I'm pretty sure of the fact that the water tank holds more then the
> holding tank. The reason I know that is because back in December
> I took my neighbor up to Sandusky to pick up his 1973 23' Canyon
> Lands from Cinnabar after having its engine overhauled.
>
> To make a long story short we left with full water and hot water tanks
> and an empty holding tank. My neighbor used the toilet in the way up
> and managed to leave the pump and sink faucet on. When we arrived
> in Sandusky, the water tank was empty and we had about 2" of water
> on the floor of the bathroom. So I'm real sure that the 40 gallon water
> tank holds more then the holding tank. At least that was the case in
> my OEM coach.
>
> I was real lucky that the holding tank contained only water from the water
> tank. It would have been a real mess if that had not been the case :(
>
> Richard Waters '76 PB, Troy, MI
>
 
> Holding tank capacity is 32 or 33 gallons thru 1977 and nominally
> 40 gallons in 1978. Cinnabar has the 40 gallon tanks as replacements
> for all units. They don't really hold 40 because they use a rubber insert
> that requires the pipes to extend down into the tank a short distance.
> Wes is full of crap when he tells you how easy the installation is.
> However, after the installation is done, it is a tremendous improvement.
> Gary Kosier

I had my holding tank replaced by Cinnabar last Summer. I'm
sure that I didn't get the 40 gallon model. They never mentioned
to me that there was a bigger tank available.

It was a major project for two of their guys to replace mine. I'm
very happy that they did it instead of me. Especially since the
first one leaked after installation and they had to take it out and
replace it with another new one.

I stood by and watched the whole thing. Even though they knew
what they were doing it took them more then 4 hours to R&R the
first one. I can just imagine how much FUN I would have had if
I had done it in my driveway.
Richard Waters '76 PB, Troy, MI
 
The one issue that comes to mind immediately, is that the bottom of the
tank is 1 1/2" lower. This means that the outlet is that much lower and
therefor you will have less of a slope to the sewer hookup. I know in my
coach (being as these are already low to the ground) this is a major issue
when hooking up.

If the majority of your camping is without sewer hookup it is worth it.
But if you typically have a hookup, for me I would rather pull the valve a
couple more times than deal with poor flow and thus possible clogs.

Just my two cents.

Rick
76 Birchaven

- -----Original Message-----
From: Gplymate [SMTP:Gplymate]
Sent: Monday, February 07, 2000 11:31 AM
To: gmcmotorhome
Subject: GMC: Holding Tank Capacity

Hi Netters,

A friend of mine is contemplating replacing his decrepit old holding tank
with a new one. Ardemco has a tank for the GMC similar to the original;
capacity is listed as 30 gallons, about the same as OEM.

He is speculating that more capacity would be very desirable and wonders
about using a deeper tank. One that is 1 1/2" deeper would increase
capacity
to over 40 gallons.

We were looking under the coach last night and it appears it would be easy
to
do and there'd be plenty of clearance. The biggest task would be to
fabricate a new center section of the crossover frame to accomodate a lower
outlet pipe.

Does anyone know if a larger capacity tank can be used, what the downfalls
might be, and what advice you might have for installing one?

Thanks in advance. It sounds like a pretty good idea to me.

Glenn
78 Kingsley II
Ondependence, OR
 
The whole situation gets worse when you add
reprocessed Beer, coffee and or soda to the holding
tank, even if the water and holding tank capacities
match. We found out the hard way years ago.

>My apologies you are correct.
>- --
>J.R. Wright
>GMC GreatLakers
>77 Eleganza II
>Michigan

>
> > OEM holding tank on the GMC is 40 Gallons
capacity.
> > J.R. Wright
> >
> >
> > > A friend of mine is contemplating replacing his
decrepit old
holding tank
> > > with a new one. Ardemco has a tank for the GMC
similar to the
original;
> > > capacity is listed as 30 gallons, about the same
as OEM.
> > >
> > > He is speculating that more capacity would be
very desirable and
wonders
> > > about using a deeper tank. One that is 1 1/2"
deeper would
increase
> > > capacity to over 40 gallons.
> > > Glenn
> > > 78 Kingsley II
>
> John,
> Are you sure of the holding tank capacity?
According to the
> owner's manual for my 1976 GMC Motorhome the Holding
Tank
> has a capacity of 32 gallons. The Living Area Water
Tank has a
> capacity of 40 Gallons.
>
> I'm pretty sure of the fact that the water tank
holds more then the
> holding tank. The reason I know that is because
back in December
> I took my neighbor up to Sandusky to pick up his
1973 23' Canyon
> Lands from Cinnabar after having its engine
overhauled.
>
> To make a long story short we left with full water
and hot water
tanks
> and an empty holding tank. My neighbor used the
toilet in the way up
> and managed to leave the pump and sink faucet on.
When we arrived
> in Sandusky, the water tank was empty and we had
about 2" of water
> on the floor of the bathroom. So I'm real sure that
the 40 gallon
water
> tank holds more then the holding tank. At least
that was the case in
> my OEM coach.
>
> I was real lucky that the holding tank contained
only water from the
water
> tank. It would have been a real mess if that had
not been the case
:(
>
> Richard Waters '76 PB, Troy, MI

__________________________________________________
Do You Yahoo!?
Talk to your friends online with Yahoo! Messenger.
http://im.yahoo.com
 
> I just went thru the holding tank system, rebuilding the slide gate valve and added a macerator pump and hose assy. along with modifing the 4" drain system to have either method available for use. Mine is very simular to this layout.
> http://www.web-access.net/~bmassey/macerator/index.html
> It helps to powerclean the tank before you start. If your tank is kept clean, then it will work and drain correctly, but if you have a build up in the tank you should consider a good cleaning.
> J.R. Wright

John,
Looks like you two have the best of both worlds! Neat setup.

I have some questions:
1) Is the point of the pump to be able to dump at more
places?
2) How long does the pump take to empty the tank as
compared to the old fashioned way?
3) How about winter time? It seems like the pump would
be very susceptible to freezing. Last December my holding
tank gate valve froze up and I had to use a hair dryer
to thaw it out in order to dump. That sure was a lot of
FUN! Now I don't camp in the cold weather.
4) Right now I dump at my neighbor's. He has a dumping
station in his driveway. Would the pump speed things
up in terms of cleaning up etc.
5) Was it as easy to install as it looks?
Richard Waters '76 PB, Troy, MI
 
This is the number one mod to most GMC's

On my site I show about 3 different mountings. It is not that hard but oh
so good to dump.

gene

>> I just went thru the holding tank system, rebuilding the slide gate
valve and added a macerator pump and hose assy. along with modifing the 4"
drain system to have either method available for use. Mine is very simular
to this layout.
>> http://www.web-access.net/~bmassey/macerator/index.html
>> It helps to powerclean the tank before you start. If your tank is kept
clean, then it will work and drain correctly, but if you have a build up in
the tank you should consider a good cleaning.
>> J.R. Wright
>
>John,
>Looks like you two have the best of both worlds! Neat setup.
>
>I have some questions:
>1) Is the point of the pump to be able to dump at more
> places?
>2) How long does the pump take to empty the tank as
> compared to the old fashioned way?
>3) How about winter time? It seems like the pump would
> be very susceptible to freezing. Last December my holding
> tank gate valve froze up and I had to use a hair dryer
> to thaw it out in order to dump. That sure was a lot of
> FUN! Now I don't camp in the cold weather.
>4) Right now I dump at my neighbor's. He has a dumping
> station in his driveway. Would the pump speed things
> up in terms of cleaning up etc.
>5) Was it as easy to install as it looks?
>Richard Waters '76 PB, Troy, MI
>
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/
 
>On my site I show about 3 different mountings. It is not that hard but oh
>so good to dump.
>
>gene
>

Great pun Gene! ROTFLMAO!

Chuck
 
Richard,

>
> > I just went thru the holding tank system, rebuilding the slide gate valve and added a macerator pump and hose assy. along with modifing the 4" drain system to have either method available for use. Mine is very simular to this layout.
> > http://www.web-access.net/~bmassey/macerator/index.html
> > It helps to powerclean the tank before you start. If your tank is kept clean, then it will work and drain correctly, but if you have a build up in the tank you should consider a good cleaning.
> > J.R. Wright
>
> John,
> Looks like you two have the best of both worlds! Neat setup.
>
> I have some questions:
> 1) Is the point of the pump to be able to dump at more
> places? YES! I CAN EVEN PUMP THE POOP INTO A TOILET IN
HOUSE AND EMPTY THE TANK.
> 2) How long does the pump take to empty the tank as
> compared to the old fashioned way? EMPTIES THE TANK
IN ABOUT 3 MINUTES.
> 3) How about winter time? It seems like the pump would
> be very susceptible to freezing. Last December my holding
> tank gate valve froze up and I had to use a hair dryer
> to thaw it out in order to dump. That sure was a lot of
> FUN! Now I don't camp in the cold weather.
I DON'T CAMP IN COLD WEATHER, BUT I WINTERIZED MY HOLDING
TANK JUST LIKE THE REST OF THE WATER SYSTEM. I FLUSH IT REAL
WELL DRAIN IT AND ADD ANTIFREEZE.
> 4) Right now I dump at my neighbor's. He has a dumping
> station in his driveway. Would the pump speed things
> up in terms of cleaning up etc. MUCH LESS MESS!!
> 5) Was it as easy to install as it looks?
REALLY WASN'T TOO BAD, I PROBABLY SPENT A TOTAL OF 6 TO 8 HOURS, BUT
I MADE THE BRACKETS FOR THE PUMP SUPPORT AND ADDED AND EXTRA DUMP
VALVE \
AFTER THE PUMP TO USE THE REGULAR 4 IN DUMP LINE. REALLY A NEAT INSTALLATION.
> Richard Waters '76 PB, Troy, MI

- --
J.R. Wright
GMC GreatLakers
77 Eleganza II
Michigan
 
Rick,
If you will look on page 24L-1 in the X7525 shop manual, which covers
the 75 & 76 motorhomes, it says approximately 32 gallons. I believe
that all the GMC interior motorhomes thru 1977 had the same basic
tank, with the different part numbers reflecting the different locations
of the openings. In the June 1995 issue of Cinnabar's BMC Motorhome
News Wes explains that the 78 model tanks are approximately 40
gallons and the current version comes without openings in the top so
that it can serve as a replacement for all GMC interior coaches.
My tank was screwed up at the factory; the first guy tried to fix the
problem with a quart of silicone. My attempt was a bit better, but
the pipes were in a strain and eventually it broke the top of the tank
I got tired of the puddles and the smell. It is possible for one person
to replace the tank out in the driveway, but it does involve a lot of
profanity. But now it's dry where I park.
Gary Kosier

- ----- Original Message -----
From:
To:
Sent: Tuesday, February 08, 2000 10:28 PM
Subject: Re: GMC: Holding Tank Capacity
 
After dumping and flushing, fill holding tank w/ clean water and then pump
it all into a 55 gal. barrel (with macerator). When all punped, measure
depth vs. total to determine quantity.

Haven't switched to macerator? Do it now!

Dave (& Dege), '76 Royale, Santa Barbara, CA
 
> In the June 1995 issue of Cinnabar's BMC Motorhome
> News Wes explains that the 78 model tanks are approximately 40
> gallons and the current version comes without openings in the top so
> that it can serve as a replacement for all GMC interior coaches.
> Gary Kosier
>

This is getting interesting for me! I went back and looked at that
issue and read that article. It would appear from what Wes wrote
that the new holding tank they sell holds about 40 gallons.

However, as I mentioned earlier, I left home recently with full
fresh water and hot water tanks on a recent trip. The holding
tank was empty. My neighbor used the toilet and managed
to leave the bathroom faucet open and the water pump on while
we drove. When we got to our destination the contents of the
fresh water tank was in the holding tank and on the bathroom floor.
There was also about 1" of standing water on the floor of the bath.
I don't think the hot water tank has anything to do with this as
the pump should stop pumping as soon as the fresh water tank
empties itself of its 40 gallon contents.

Based on that I could only conclude that my Cinnabar holding
tank does not hold as much liquid as the fresh water tank.

I guess I'll have to empty the holding tank and pour a
known quantity of water into the toilet until it fills. Then I
will know the exact capacity of the holding tank.
Richard Waters '76 PB, Troy, MI
 
> Richard,
>
> > 5) Was it as easy to install as it looks?
> REALLY WASN'T TOO BAD, I PROBABLY SPENT A TOTAL OF 6 TO 8 HOURS, BUT
> I MADE THE BRACKETS FOR THE PUMP SUPPORT AND ADDED AND EXTRA DUMP
> VALVE \
> AFTER THE PUMP TO USE THE REGULAR 4 IN DUMP LINE. REALLY A NEAT INSTALLATION.
> --
> J.R. Wright

John,
Thanks for all the information. This sounds like something I will do this
Summer.
Richard
 
Nice job, worth several thousand words!

Tony

- ----- Original Message -----
From:
To:
Sent: Wednesday, February 09, 2000 5:33 AM
Subject: Re: GMC: Holding Tank Capacity

>
> TO WHOM IT MAY CONCERN:
>
> I PUT SOME PICTURES OF HOLDING TANK WITH BUBBLE TALK ON MY WEBSITE FOR MY
> SIDEBATH 75 PB. IF INTERESTED THEY ARE AT
> http://members.aol.com/adohen/advice/Variousphotos.htm
>
> I think the label on my tank verifies the fact that mine is 32 gals--
>
> SCOTT NEHODA'S
> BACK YARD
>
 
since all the other pictures are there, I looks like your link to the LOGO
picture is just wrong... may be pointing to the wrong directory or maybe
you did not click the box that says leave the picture where it is ?? I
think it is just a link problem ?? hard to tell from this side.

gene

>In a message dated 2/9/2000 6:51:00 AM Eastern Standard Time,

>
>> PS your top LOGO is broken on the page
>
>Thanks Gene-- I know --That is the reason I have been up all night--still
>can't figure out what is wrong--maybe some hackers are trying to shut down
my
>websites--any ideas?
>
>Scott NEHODA'S
>BACK YARD
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/
 
Richard,
Hi, guy! Say, why would your pump shut off when the water runs out? I was
draining my system this Fall (we never really haven't had any winter yet
here in "The Big O", just been a long fall) and noticed my pump would sit
there fat, dumb and happy running till it burns itself out if I'd let it.
Just curious is all... Take care.

Nate '75GB (Man, those Jim K. 3.55 gears are great!) Omaha

PS. Speaking of long Fall, I've ridden the ol "Bad Boy"
http://www.tconl.com/~chase/images/badboy2.jpg three times this year
already. I'm even taking a mental health day today (they own me a bunch for
Y2oK). What with 60 degrees here yesterday and forecast of the same today
you know where I'll be this afternoon (60 degrees = 60 MPH) =8-). There is
something to be said for not tearing the bike down every year! Guess I'll
just have to tell everyone that it's last years model (g).


I don't think the hot water tank has anything to do with this as
the pump should stop pumping as soon as the fresh water tank
empties itself of its 40 gallon contents.
 
> Richard,
> Hi, guy! Say, why would your pump shut off when the water runs out? I was
> draining my system this Fall (we never really haven't had any winter yet
> here in "The Big O", just been a long fall) and noticed my pump would sit
> there fat, dumb and happy running till it burns itself out if I'd let it.
> Just curious is all... Take care.
>
> Nate '75GB (Man, those Jim K. 3.55 gears are great!) Omaha
>

Hi Nate,
Ah yes, I have to be careful of what I say. I should have said that the pump
was running when we shut the motorhome down. But nothing was pumping
because the tank was empty. Does that make more sense?

Too bad about your lack of Winter. Do you want us to send you some of
ours?
Richard
 
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