Still Siphoning

mtdawg · 09-06-2020, 04:10 PM

Just a minute to vent while the vent to my fresh water tank siphons. I know this thread has been beaten to death, but here goes. This is my fifth Jayco RV and the last four of them have had this problem. What bugs me is that when I mention it to the dealer in passing, they play ignorant. I wonder if other brands are doing the same thing? It's more of a nuisance rather than a serious problem, it just seem as though it should have to be this way. Typically the water will flow through both tubes depending on how quickly I get the hose turned off. Sorry the picture is sideways. Not sure how that happened.

Jim

chas111 · 09-06-2020, 07:08 PM

While filling the tank - I let it fill a couple minutes then I shut it off, go inside and run the water for a few seconds to get the air out. Then I go back outside, turn the water on, and continue refilling.

Mopar_Earl · 09-06-2020, 08:06 PM

I out a valve on my vent and clip the over flow rubber flap folded over. I fill till it runs out the over flow the fold and clip it. Then wait till it flows out the vent, then I close the valve. I let the tank fill for a minute or two and call it full. Once setup, I open the vent valve so the tank can breathe when the pump runs.

Earl

OTTERCOMET · 09-07-2020, 06:35 AM

There is a fix for this and our dealer made the repair under warranty.
The problem stems from the fact that the fresh water tank is only 5" deep and the overflow tube reaches almost to the bottom of the tank - so once the siphon starts it will drain 2/3 rds or more of the content.
The fix involved opening the under belly to get at the tank and the way the fix was described to me, it involved extending the length of the overflow tube and creating a loop in the tube to stop the siphon.
Whatever they did worked as I no longer loose volume while travelling - which was when we seemed to loose most of our fresh water supply. The tank would show full while sitting in the driveway at home but when we got to our destination it was down to less than 1/3 rd.

CleaverF22 · 09-09-2020, 04:02 AM

I am new to a Jayco 5th Wheel 377 and haven’t been camping yet. I’ve filled the fresh water to indicate “full” and don’t even see this overflow valve underneath anywhere. Anyone know where it is?

Mopar_Earl · 09-09-2020, 04:43 AM

Quote:

Originally Posted by CleaverF22

I am new to a Jayco 5th Wheel 377 and haven’t been camping yet. I’ve filled the fresh water to indicate “full” and don’t even see this overflow valve underneath anywhere. Anyone know where it is?

Is no valve unless you add one. Should find a vent hose and a rubber inner tube looking overflow. Should be sticking through the underbelly near the tank.

Earl

Cavie · 09-09-2020, 04:47 AM

Quote:

Originally Posted by CleaverF22

I am new to a Jayco 5th Wheel 377 and haven’t been camping yet. I’ve filled the fresh water to indicate “full” and don’t even see this overflow valve underneath anywhere. Anyone know where it is?

Some have a vent hole right at the fill port opening.