Black tank flush valve not working

Sonders · 03-30-2021, 05:51 PM

Just got home from our first outing in our new to us 2015 Passport 2400BH. Found a few small things to address, but all small things. Only issue that I am not sure on is the black tank flush valve did not work when dumping.
Took a look when we got home and I see where the pex line comes into the camper to the check valve and then to the black tank. It appears the line has a kink in it not allowing water to flow in. I disconnected it from the check valve to straighten it out. It runs up under the bathroom sink.
Is there a reason the lines should be this long or can I shorten then to eliminate the kink in the line? First pic is the kinked line coming in, and second pic is the check valve and line running down to black tank just below sink (after incoming line was disconnected).

**chuckster57** · 03-30-2021, 06:16 PM

Other than the valve needs to be at least 6 inches above the black tank, you can shorten the pex. I would simply get a 90 degree fitting and keep the valve up high.

Sonders · 03-30-2021, 06:37 PM

Thanks Chuckster, i may just go that route then.

bobbecky · 03-30-2021, 08:14 PM

Quote:

Originally Posted by chuckster57

Other than the valve needs to be at least 6 inches above the black tank, you can shorten the pex. I would simply get a 90 degree fitting and keep the valve up high.

I'm sure you meant 6" above the lip of the toilet for the backflow/air gap valve?

Sonders · 03-31-2021, 03:09 AM

Ehh close enough bobbecky, I’m going to roll with it and leave the lines the length they are and add 90* elbow and see if that fixes it.

ChuckS · 03-31-2021, 03:26 AM

OP - do yourself a big improvement and either remove that plastic OEM anti siphon valve completely and connect the two lines with a shark bite coupler or replace the anti siphon valve with an all brass one..

Otherwise you WILL have flooded RV sooner than later

notanlines · 03-31-2021, 04:04 AM

OP, what they said. If you need numbers and outlets to order brass PM me.

Sonders · 03-31-2021, 05:44 AM

Chuck and Notanlines, can you give me more details please? This is our first camper with the flush valve feature so pretty clueless about it. Also I hate plumbing and it is not my forte; more comfortable with electrical.

Skippy38 · 03-31-2021, 10:28 AM

Quote:

Originally Posted by Sonders

Chuck and Notanlines, can you give me more details please? This is our first camper with the flush valve feature so pretty clueless about it. Also I hate plumbing and it is not my forte; more comfortable with electrical.

This is what I did to fix my valve. Very easy to do and cost is about $5...

https://www.youtube.com/watch?v=urywWdM6TrA

Sonders · 04-15-2021, 11:46 AM

just a quick update on this. I cut out the kink in the pex line and installed a 90 in the line. I also installed brass anti-siphon valve and backflow preventer as recommended above. I tested it out and still not getting any water into the tank, so I removed the brass components and went with just a a couple of pipe fittings for optimum flow to try out as well. Still no go. Also, I've noticed when I unhook my garden hose from the outside connector, the backed up water in the line shoots out around the fitting, into the opening in wall and onto the bathroom floor. Not sure how the heck the water is coming in around the outside fitting as it seems to be 1 piece going through the wall of camper. I'm puzzled and a little pissed that something that should be simple has me defeated thus far.
here is the brass valve I went with, incoming line to lower side and outgoing to tank on right side (I had already pulled off right side internal coupler in picture).

2nd picture is the pvc fittings I used after removing the brass valve, still with no luck getting the water to flow into tank.

Webbhead · 06-01-2021, 12:52 AM

Quote:

Originally Posted by Sonders

just a quick update on this. I cut out the kink in the pex line and installed a 90 in the line. I also installed brass anti-siphon valve and backflow preventer as recommended above. I tested it out and still not getting any water into the tank, so I removed the brass components and went with just a a couple of pipe fittings for optimum flow to try out as well. Still no go. Also, I've noticed when I unhook my garden hose from the outside connector, the backed up water in the line shoots out around the fitting, into the opening in wall and onto the bathroom floor. Not sure how the heck the water is coming in around the outside fitting as it seems to be 1 piece going through the wall of camper. I'm puzzled and a little pissed that something that should be simple has me defeated thus far.
here is the brass valve I went with, incoming line to lower side and outgoing to tank on right side (I had already pulled off right side internal coupler in picture).

2nd picture is the pvc fittings I used after removing the brass valve, still with no luck getting the water to flow into tank.

Did Yiu ever get to the bottom of this? I’ve run into the same issue with my Montana 3761FL

Sonders · 06-01-2021, 07:13 AM

Webhead, no I have not fixed yet. I had a discussion with Chuckster57 and we narrowed it down to the line running under the floor into the tank is smashed shut, probably done when installed at factory. I haven't had time to pull the Coraplast down underneath to take a look yet as we've been busy camping in it anyways. That has to be the problem as I've traced and removed the rest of the line all the way from where it enters through the wall to the floor.

Webbhead · 06-01-2021, 07:28 AM

Well nuts. I need to pull my anti-siphon out of the loop to eliminate it from the problem. Based on the amount of water coming out when the fitting was loose, I don't believe I have a water line issue.....Sure seems water is getting to the valve. This weekend I'm going to try it withOUT the valve to see if I can get water spraying into the tank.

I take it water wasn't even making it to your anti-siphon, from the inlet, hence you've determined you have a crushed/pinched pex line somewhere along the way?.

Sonders · 06-01-2021, 07:44 AM

Quote:

Originally Posted by Webbhead

Well nuts. I need to pull my anti-siphon out of the loop to eliminate it from the problem. Based on the amount of water coming out when the fitting was loose, I don't believe I have a water line issue.....Sure seems water is getting to the valve. This weekend I'm going to try it withOUT the valve to see if I can get water spraying into the tank.

I take it water wasn't even making it to your anti-siphon, from the inlet, hence you've determined you have a crushed/pinched pex line somewhere along the way?.

I could get water to the anti-siphon and past it; just wasnt' getting to the tank. Water would just build up pressure in the line and then nada.

Webbhead · 06-01-2021, 07:48 AM

That is a big bummer. You'd love to take it to the dealer for them to deal with, but the sad part is, they'd keep your rig for 6 weeks.....puts a damper on the summer.

Brantel · 06-02-2021, 03:31 AM

Quote:

Originally Posted by Webbhead

Well nuts. I need to pull my anti-siphon out of the loop to eliminate it from the problem. Based on the amount of water coming out when the fitting was loose, I don't believe I have a water line issue.....Sure seems water is getting to the valve. This weekend I'm going to try it withOUT the valve to see if I can get water spraying into the tank.

I take it water wasn't even making it to your anti-siphon, from the inlet, hence you've determined you have a crushed/pinched pex line somewhere along the way?.

Did you try turning your valve around. Many of these are installed backwards at the factory.

**sourdough** · 06-02-2021, 07:10 AM

Quote:

Originally Posted by Webbhead

Well nuts. I need to pull my anti-siphon out of the loop to eliminate it from the problem. Based on the amount of water coming out when the fitting was loose, I don't believe I have a water line issue.....Sure seems water is getting to the valve. This weekend I'm going to try it withOUT the valve to see if I can get water spraying into the tank.

I take it water wasn't even making it to your anti-siphon, from the inlet, hence you've determined you have a crushed/pinched pex line somewhere along the way?.

Take the anti siphon out and replace with elbows or replace it. My last trailer wouldn't work. Pressured up and spewed water all over me from the inlet. Removed valve and all was good.

Webbhead · 06-02-2021, 11:13 AM

That's my plan too, Sourdough!

Sonders · 06-02-2021, 12:47 PM

Quote:

Originally Posted by Webbhead

That's my plan too, Sourdough!

Hopefully that works for you. I tried eliminating the anti-siphon valve on mine and going with pvc elbow but still no dice. Water flows into the line, but it doesn't go into the tank. I even tried hooking up air line to blow air through the line with no luck.

skids · 06-02-2021, 03:44 PM

Quote:

Originally Posted by Sonders

Hopefully that works for you. I tried eliminating the anti-siphon valve on mine and going with pvc elbow but still no dice. Water flows into the line, but it doesn't go into the tank. I even tried hooking up air line to blow air through the line with no luck.

The city water inlet has a check valve. The city water inlet looks a lot like the black flush inlet. I suspect that it also has a check valve. Is it possible that it is malfunctioning?

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