RV Newbie needing help with tank flush

[Popegitmo]

I am very new to this and all of the terms are overwhelming. I drained my black tank today for the first time and tried to use the flush but the tank does not allow water from the hose to go in. It just builds up pressure. I have the drain valve open, but the warning says to have the full way termination valve open. I have seen several people say that this is the drain valve. If that is the case why can’t I flush my black tank? 2017 Crusader Lite 30BH.

[flybouy]

Yes it is the drain valve. Why is it not working? Could be it's clogged with debris or it could be the anti-siphon valve or it could be the water line is pinched off or kinked.

[sourdough]

Here is a link to your trailer;

https://www.youtube.com/watch?v=v3tztOfxmqA

I suspect the anti siphon valve. Had the same thing happen to me on one several years back, just built up pressure and would blow back water. Replaced the valve under the bathroom sink.

BTW, welcome to the forum!

Edit: You do not say what you're tow vehicle is but a perfect example of how owners of 1/2 ton trucks get into problems is this salesman talking at about the 30 second mark. A salesman but knows nothing about trailers or trucks.

[LHaven]

It's not uncommon for the anti-siphon valve on the flush line to be installed backwards.
That produces exactly this symptom.

[bsmith0404]

Scary part is that whatever your problem is (most likely anti siphon as mentioned). How long has it been since the black tank was actually flushed well? You may have some build up to get rid of.

[bsmith0404]

Originally Posted by sourdough

Edit: You do not say what you're tow vehicle is but a perfect example of how owners of 1/2 ton trucks get into problems is this salesman talking at about the 30 second mark. A salesman but knows nothing about trailers or trucks.

The dealership I used to work at sold those at one time. I had to educate all the salesman there that it was too heavy for a half ton. That one is actually really light compared to Prime Times other “half ton towables”. Most of their models were around 1,500 brochure pin weight.

[markcee]

Originally Posted by bsmith0404

The dealership I used to work at sold those at one time. I had to educate all the salesman there that it was too heavy for a half ton. That one is actually really light compared to Prime Times other “half ton towables”. Most of their models were around 1,500 brochure pin weight.

Maybe my nephew bought from that dealer....lol.

Here's his Crusader mated up to his F150. The dealer told him 'no problem, you have the max tow package!' Thankfully he has since moved up to a 3/4 ton Ram.

[jxnbbl]

Actually I had the same problem with our new trailer in 2020. I brought the thing back 2 times and in the months we used the trailer I got into a routine of:


1. empty the black tank
2. fill it 1/3+ with water
3. drive to next campground
4. empty.


On our last stop I bought one of those "back flush" devices to clean out as good as possible.


In our case, I believe, the pex plumbing to the flush was crimped and not accessible without dropping the tank....It became the dealers problem as I just traded it in.

[Camp CA]

Originally Posted by Popegitmo

...........but the warning says to have the full way termination valve open. I have seen several people say that this is the drain valve. If that is the case why can’t I flush my black tank? 2017 Crusader Lite 30BH.

Your 2017 Crusader Lite 30BH fifth wheel trailer reportedly has 2 gray tanks https://www.rvusa.com/rv-guide/2017-...n-30bh-tr28832 and each should have their own flush and drain valve, one for each. Is that what you have? Suggest checking the screen for pluggage where the flush hose is connected. If the screen is not plugged and still will not pass water then remove it and verify the line is clear before more more extensive surgery.

[travelin texans]

Originally Posted by Camp CA

Your 2017 Crusader Lite 30BH fifth wheel trailer reportedly has 2 gray tanks https://www.rvusa.com/rv-guide/2017-...n-30bh-tr28832 and each should have their own flush and drain valve, one for each. Is that what you have? Suggest checking the screen for pluggage where the flush hose is connected. If the screen is not plugged and still will not pass water then remove it and verify the line is clear before more more extensive surgery.

Just to be clear, the Grey tanks WILL NOT have a flush line in them, only the black tank. Typically you'll have 1 - 3" drain connection for the black tank & at least 1 of the Grey tanks with valve handles for each in the same location, if the kitchen & bath are significantly separated in the rv the manufacturer may have played hide n seek with the 2nd Grey valve which requires crawling around underneath to locate.
Apparently the previous owner never used the black tank flush line & its installed backwards, the line is kinked somewhere or it's plugged up with TP inside the tank. From your description I'd guess the anti siphon valve is backwards. Personally I'd remove that valve, it's a known problem leaking if it's the plastic one, then replace it with 2 - 90 degree bends eliminating the valve & add the water hose back Flo preventer at the flush connection.

[notanlines]

"Your 2017 Crusader Lite 30BH fifth wheel trailer reportedly has 2 gray tanks and each should have their own flush and drain valve, one for each."
As Danny mentioned this is probably not true. Only higher end RV's have a grey tank flush, they are not very common.

[Camp CA]

Correction......2 "black" tanks with separate flush connections and drain valves.

[Popegitmo]

I do have two black tanks. And two black handles. Only saw one flush valve. Previous owners never used black tank.

[LHaven]

Originally Posted by Popegitmo

I do have two black tanks. And two black handles. Only saw one flush valve. Previous owners never used black tank.

Yup. Two toilets, widely spaced, so two tanks. Why they would have plumbed only one for flush beats me. Previous owners skipped using second bathroom entirely? Mysteries cascade!

[Popegitmo]

Previous owners did not use either bathroom is what they said. I hope they were honest about it, lol

[JRTJH]

Originally Posted by Popegitmo

Previous owners did not use either bathroom is what they said. I hope they were honest about it, lol

On some trailers (certainly not all) the front/main toilet is plumbed to the black tank and that's all that goes into that tank. The sink/shower are plumbed to the gray tank. That black tank only has water from the toilet, so a flush system helps add water and rinse the tank...

That said, on the rear toilet black tank, typically the sink will also dump into that black tank, so there is "increased water" in the tank. Some manufacturers will cut costs by not installing a flush system, claiming that the sink will provide enough additional water to keep the tank "flushable without a flush system"...

What's in your trailer is anybody's best guess, but if you can't find a flush system, then I'd suspect that only the front tank has a flush system.

[travelin texans]

Originally Posted by Popegitmo

Previous owners did not use either bathroom is what they said. I hope they were honest about it, lol

Will wonders never cease!
A 6-7 year old nice rv that the PO never used the toilets?
I can't understand the reasoning behind this madness!
Or those that would rather save toilet paper in a bucket next to the toilet rather flush it as it was intended to be.
FYI, if you use septic safe, no more than 2 ply toilet paper with a bowl full of water you likely never have an issue using the toilet.
Also FYI, the sensors for tank levels won't give you any accurate information of how much is in the tanks other lighting the pretty red lights on the panel.

[sourdough]

I don't believe your trailer has a 2nd black tank flush. As John mentioned they are going to consider the sink with the toilet in the back as the "flush" water.

If you watch the video the sales guy points both drains, all the docking points etc. Everything is there above the front drain with the main bathroom including the black tank flush. The rear bath black tank drain is pointed out and if you watch the guy as he works around the trailer you won't see anything that looks like it might be, or contain, a black tank flush port. And as a side note; why in the world would anyone buy a floorplan with TWO toilets but not use them??? Hmmmm.....me thinks I smell something.

I also failed to clarify in post #3 that my anti siphon valve was backward. Symptoms sound exactly like yours.

[jvbutter01]

Originally Posted by markcee

Here's his Crusader mated up to his F150. The dealer told him 'no problem, you have the max tow package!' Thankfully he has since moved up to a 3/4 ton Ram.

yea its amazing what a dealer will tell you just to make a sale. Mine didnt look at my actual truck sticker. Just assumed it was "all good, its a truck, and this is the Lite version trailer"