Need plumbing advice, please?

[dave king]

I'm not a GMCMH owner but I've been follong the Forum (on-line version for many years)
I note your coach is a "Coachman". Do you know if it has one holding tank or two ?
If it has 2, the sink and the shower probably go to the same tank.

Is the black tank for the toilet directly under the toilet like on GM up fitted coaches ?
If it has 2 tanks are you sure you dumped both?
As someone has said, you may have pulled the handle, but it's possible the valve
didn't actually open and the tank is not empty. Can you check that?
--
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada

 

[mike]

Thanks for the ideas and suggestions fellows.

Initially my thought was a venting issue but after adding the second vent pipe didn't resolve the water backing up into the shower I wondered if it
had something to do with direct venting to the atmosphere.

Ken H indicates that venting isn't the likely cause of my problem although it may cause a small amount of water not the amount I'm experiencing. So I
need to look at other options like snaking the drains again in case it is a blockage of some type.

James, I'm quite certain I have two tanks and the main drain pipe services the lounge sink, bathroom sink and the shower.

Dave, I believe I have two tanks & two drain valves (one for each tank). Last summer, assuming the tanks were empty, (the fellow who did my
per-purchase inspection confirmed both tanks were empty) I decided to run water into both the grey tank via the lounge & bathroom sink as well as the
black tank via the toilet. When I pulled 1st the black dump valve I got what I expected, very little liquid. The same with the grey tank, only what
limited amounts of water I ran through appeared to exit via the main dump pipe.

You could clearly see the result of opening each valve. Maybe I need to repeat this exercise, fill my water tank and empty 50% of it into each tank
then empty each tank separately to try and identify the amount of water exiting.

The toilet appears to dump directly into the black tank and it looks like the main drain pipe connects the lounge, bathroom and shower. I will try and
get some links to photos for you to look at.

In the meantime here is a quick schematic I just drew up giving you an idea of my set up...
http://www.gmcmhphotos.com/photos/my-75-royale/p64489-plumbing-schem-of-gmc.html

Thanks again,
Mike