Rv sinks not draining

[Bracerorv]

We have a jayco jay flight 38bhds
Our kitchen sink has been giving us issues for a year-expected. We have used a hand held plumber, taken apart the kitchen pipes and cleaned out, snakes, drano, even went as far as “fixing a upward slant in the piping.” This issue is now becoming worse as the bathroom sink is starting to cause back up and bubbling into the kitchen sink.
Also We are guilty of leaving our gray tank open.
Any information or suggestions would help.

 

[TheBar]

The sink or gray tank vent may be plugged. I have an air pressure drain blaster similar to this but mine can operate off an air tank for higher pressure. An ordinary toilet plunger can also do miracles if you plug up the overflow hole and get the plunger seated tight over the sink drain.

 

[RRR]

The only time I ever tried a plunger the crossover pipe between the two sinks blew off. Clean up was a lot longer than taking off the trap.

 

[Bracerorv]

The sink or gray tank vent may be plugged. I have an air pressure drain blaster similar to this but mine can operate off an air tank for higher pressure. An ordinary toilet plunger can also do miracles if you plug up the overflow hole and get the plunger seated tight over the sink drain.

hmm I wonder if a pressure washer could do the same thing. We’ve definitely tried a plunger and it helps for a day or two but doesn’t solve the problem

 

[Bracerorv]

The only time I ever tried a plunger the crossover pipe between the two sinks blew off. Clean up was a lot longer than taking off the trap.

Yeah that sounds like an awful experience. I’ve taken the entire sink apart twice and cleaned it out. Only helped drainage for a week

 

[Domo]

The sink or gray tank vent may be plugged. I have an air pressure drain blaster similar to this but mine can operate off an air tank for higher pressure. An ordinary toilet plunger can also do miracles if you plug up the overflow hole and get the plunger seated tight over the sink drain.

Although drain blasters are very hand tools to have, please be wary of pressurized solutions in RV plumbing - sadly, many DIY owners have found that some joints are NOT solvent welded and have only been slipped together, perhaps just before the factory lunch horn signaled it was break time. Second, AAVs sometimes get blown "backwards," although less frequently from what I've read.

Of course, some are assembled perfectly and are bullet-proof.

OP - if me, I'd go on the roof with a hose, remove any fancy caps to the vent pipes and then try flushing from above. If the vent pipe fills with water, you have a blockage and can snake it from above.

Good luck and let us know what you do to solve the problem.

 

[Bracerorv]

Although drain blasters are very hand tools to have, please be wary of pressurized solutions in RV plumbing - sadly, many DIY owners have found that some joints are NOT solvent welded and have only been slipped together, perhaps just before the factory lunch horn signaled it was break time. Second, AAVs sometimes get blown "backwards," although less frequently from what I've read.

Of course, some are assembled perfectly and are bullet-proof.

OP - if me, I'd go on the roof with a hose, remove any fancy caps to the vent pipes and then try flushing from above. If the vent pipe fills with water, you have a blockage and can snake it from above.

Good luck and let us know what you do to solve the problem.

That’s a good idea. Tricky execution. I’ll give it a try.

 

[Domo]

That’s a good idea. Tricky execution. I’ll give it a try.

I had frogs living in my gray tank vent pipe at one time.

BTW, you may have to scrape old Dicor (self-leveling sealant around the vent caps/screws available at any RV store and sometimes ACE) off so that you can remove the cap - be gentle to your roof, be patient and it will remove enough so that you can remove the cap. You'll need to apply new Dicor when you're done (uses a caulking gun) and that will give you the opportunity to touch up any other horizontal roof spots that might look questionable - which is a task all owners should know to do.

 

[Gary RV_Wizard]

We are guilty of leaving our gray tank open.

Nothing wrong with that, unless perhaps you are in the habit of washing food debris down the drain. That would be problematic in any case, but especially so with the drain open.

If taking the sink drain & trap apart and cleaning helps for a week, something is getting into the drains and plugging them up again. Most likely from the sink side, so maybe someone is being less than cautious?

The roof vent shouldn't be an issue if the gray drain valve is open - plenty of air can enter that way. However, the air admittance valves (AAV) under each sink could still cause sluggish flow.