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Old 10-10-2019, 04:05 AM   #1
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Brand: Thor Motor Coach
Model: 2020 Thor Outlaw 29J
State: California
Posts: 10
THOR #16597
2020 Outlaw kitchen sink drains very slow

We just bought this new Outlaw and while inspecting it at the dealer I noticed that the kitchen sink drained very slow and the p-trap is installed right up against the bottom of the sink such that the water level sits at the strainer in the bottom of the sink. When I say slow, I mean that a quart of water takes about 20 seconds to drain when it should take about 5 seconds. The mechanic didn't think it was a big deal and I figured that I could fix it so I let it slide. At first, I thought there was not enough drop to the p-trap and I would just lower the p-trap (I am a general contractor). Unfortunately, there is not enough room to lower the p-trap. I removed the AAV and inspected it. The AAV is not defective (I also tried a new AAV just to make sure), and without the AAV installed the drain flows as it should. This tells me that water in the drain is developing pressure in the drain line instead of a vacuum which is preventing the AAV from opening. I am assuming that this may be happening because there is no vent on the grey water tank itself. However, I tested the sink drain with the grey water tank drain valve open and it was still slow draining. I would think this relieved any pressure but maybe not for some reason? The tank is very oddly shaped with a large flat section that stretches over under the kitchen sink. I confirmed that there are no blockages between the sink and the top of the grey water tank. Most people would say that I should just take it in for the dealer to fix under warranty, but I fix things for a living and I generally don't trust other people to fix things for me unless it is my last resort. By the way, we went on our first camping trip and everything else is working good, except for the low ground clearance, so I have a 6" lift kit ordered.
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Old 10-10-2019, 11:24 AM   #2
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Brand: Thor Motor Coach
Model: Aria 4000
State: Utah
Posts: 66
THOR #15943
That does sound odd. Our Aria 4000's kitchen sinks (twin) don't even have P-traps, and fell off on our last trip-both the coupling screw caps broke off. I suspect it broke because it was so rigidly installed that it had no capability to flex when rolling down the road.



Good luck-let us know what you find out.
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Old 10-10-2019, 12:43 PM   #3
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Model: Tiffin Wayfarer 24 BW
State: New York
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THOR #8860
Could it be that the strainer is full of construction debris?

By the way: I'm glad to hear that your shakedown cruise was successful!
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Old 10-10-2019, 01:54 PM   #4
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Brand: Thor Motor Coach
Model: Outlaw 29J
State: California
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THOR #7466
Quote:
Originally Posted by Handy View Post
We just bought this new Outlaw and while inspecting it at the dealer I noticed that the kitchen sink drained very slow and the p-trap is installed right up against the bottom of the sink such that the water level sits at the strainer in the bottom of the sink. When I say slow, I mean that a quart of water takes about 20 seconds to drain when it should take about 5 seconds. The mechanic didn't think it was a big deal and I figured that I could fix it so I let it slide. At first, I thought there was not enough drop to the p-trap and I would just lower the p-trap (I am a general contractor). Unfortunately, there is not enough room to lower the p-trap. I removed the AAV and inspected it. The AAV is not defective (I also tried a new AAV just to make sure), and without the AAV installed the drain flows as it should. This tells me that water in the drain is developing pressure in the drain line instead of a vacuum which is preventing the AAV from opening. I am assuming that this may be happening because there is no vent on the grey water tank itself. However, I tested the sink drain with the grey water tank drain valve open and it was still slow draining. I would think this relieved any pressure but maybe not for some reason? The tank is very oddly shaped with a large flat section that stretches over under the kitchen sink. I confirmed that there are no blockages between the sink and the top of the grey water tank. Most people would say that I should just take it in for the dealer to fix under warranty, but I fix things for a living and I generally don't trust other people to fix things for me unless it is my last resort. By the way, we went on our first camping trip and everything else is working good, except for the low ground clearance, so I have a 6" lift kit ordered.







Hello Handy, When you check for blockage was that also from the AAV down the pipe.
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Old 10-10-2019, 03:29 PM   #5
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Brand: Thor Motor Coach
Model: 2020 Thor Outlaw 29J
State: California
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THOR #16597
I removed the p-trap which was clean and inserted a 1/4" hose through the drain pipe and down to where it enters the holding tank below the drawers. I also inserted the hose from the AAV down to the same point and it appeared to be clear. Also considering that the drain speed is normal without the AAV indicates that the pipes are clear. There is only one 360 Vent on the roof so I will assume that the black and grey tank vents combine into this. The vent is on the opposite side of the motorhome from the kitchen sink. I looked at the grey tank configuration closer this morning and it is very custom! It is about a 3" deep pancake spreading about 4'x4' under the floor with a deeper collection area on the opposite side of the motorhome by the main drain. There is a little finger at the edge of the grey tank where the drain pipe from the kitchen sink enters it. The grey tank is secured to the bottom of the floor at this point to keep it high and then slopes downwards to the other side of the motorhome at the main drain. My thoughts are that all the other drains are working so the kitchen sink end of the grey holding tank must not be benefitting from the holding tank vent. On another note, while inspecting the grey holding tank I found a cluster of 8-10 hoses, conduit, and wires wedged between the holding tank and the top of the chassis on the low side of the tank where it is supposed to rest on the chassis. Over time, especially driving with a full grey tank, these will get pinched between the holding tank and the chassis so they will need to be pulled out of there. Maybe this will affect my venting issue when the tank is able to come down a little more and rest on the chassis. Also, the abs pipe coming out of the grey tank is sloped upwards before it turns down to the main drain so I might have to add a couple of rubber couplings to allow it to stope downwards properly. I also found a rubber fuel hose pulled tight against a sharp metal edge a few feet forward of the gas tank in the rear.
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Old 10-10-2019, 04:14 PM   #6
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Brand: Thor Motor Coach
Model: 2013 ACE 30.1
State: Alberta
Posts: 921
THOR #2631
I would agree that when AAV is removed and there is no issue with water leaving the sink, that there is likely no blockage downstream into the grey tank; and probably the shared roof vent is open as well. So if the AAV valves are good, then there is simply not enough vacuum being created by water leaving the sink and flowing through the trap to open the AAV properly IMO. Not sure if that is because there is little or no tail stock height below the sink (per your description) and before the trap to help create more head pressure (more vaccum on the AAV as waater goes down)? So how do you create more vacuum in that column of sink water to activate the AAV.....you said you have no room for a longer tailstock pipe before the trap.....and I don’t know if all AAV’s operate at the same set vacuum levels either.......raise the sink? Interesting problem.
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Old 10-10-2019, 04:16 PM   #7
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Brand: Thor Motor Coach
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THOR #7466
Quote:
Originally Posted by Handy View Post
I removed the p-trap which was clean and inserted a 1/4" hose through the drain pipe and down to where it enters the holding tank below the drawers. I also inserted the hose from the AAV down to the same point and it appeared to be clear. Also considering that the drain speed is normal without the AAV indicates that the pipes are clear. There is only one 360 Vent on the roof so I will assume that the black and grey tank vents combine into this. The vent is on the opposite side of the motorhome from the kitchen sink. I looked at the grey tank configuration closer this morning and it is very custom! It is about a 3" deep pancake spreading about 4'x4' under the floor with a deeper collection area on the opposite side of the motorhome by the main drain. There is a little finger at the edge of the grey tank where the drain pipe from the kitchen sink enters it. The grey tank is secured to the bottom of the floor at this point to keep it high and then slopes downwards to the other side of the motorhome at the main drain. My thoughts are that all the other drains are working so the kitchen sink end of the grey holding tank must not be benefitting from the holding tank vent. On another note, while inspecting the grey holding tank I found a cluster of 8-10 hoses, conduit, and wires wedged between the holding tank and the top of the chassis on the low side of the tank where it is supposed to rest on the chassis. Over time, especially driving with a full grey tank, these will get pinched between the holding tank and the chassis so they will need to be pulled out of there. Maybe this will affect my venting issue when the tank is able to come down a little more and rest on the chassis. Also, the abs pipe coming out of the grey tank is sloped upwards before it turns down to the main drain so I might have to add a couple of rubber couplings to allow it to stope downwards properly. I also found a rubber fuel hose pulled tight against a sharp metal edge a few feet forward of the gas tank in the rear.

I will look at mine when I get a chance see if anything looks odd,Thanks for the fuel hose fyi.
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Old 10-10-2019, 04:16 PM   #8
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Brand: Still Looking
Model: Tiffin Wayfarer 24 BW
State: New York
Posts: 11,283
THOR #8860
Could the vent up on the roof be blocked somehow?
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Old 10-18-2019, 02:14 AM   #9
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Brand: Thor Motor Coach
Model: 2020 Thor Outlaw 29J
State: California
Posts: 10
THOR #16597
Update on this slow drain. I rebuilt the p-trap and drain pipes to go around the drawers so I could lower the p-trap 3.5" which increases the height of the AAV valve and moves the water level down below the basket strainer. The drain is still slow but it is visually much better as the water level disappears into the tailpiece. I also tried tilting the motorhome to create more slope in the grey tank away from the outlet of the kitchen sink drain pipe and it had no effect. I am still uncertain of why this drain is so much slower than the shower drain. Coincidentally I received communications from the Thor concierge department stating that they want to contact me several times in the next year to see how the motorhome is doing and how the dealer is doing. They gave me contact info and encouraged me to contact them with anything at any time. I sent a detailed email describing my slow drain, pinched wires and fuel line under the grey tank, and outlet pipe from grey tank sloping up. I also included a drawing of the drain circuit. I was positive, provided facts, and simply asked if they could provide me with any information that might help me. It has been 4 days and I have received no reply from Thor. At this stage I am going to be happy with the progress I have made on the drain, continue working on the other issues myself, and not have any expectations of what Thor's concierge department might do for me.
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Old 10-18-2019, 12:55 PM   #10
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THOR #2631
Sorry to hear no fast drainage success as yet. The other way to look at it is probably that the real purpose of the AAV is not for sink drainage, but rather to prevent the sink P trap water from being siphoned off when other water devices/drains are being used in the coach. So maybe the odd shape of the grey tank is a contributing factor (for easier blockages) and I am wondering if just using a small diameter flex hose as a snake is adequate to make sure the drain pipe is totally clear. What about trying a proper plumbing snake?
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