Originally Posted by RWP
Does anyone know where the blank tank flush check valve (vacuum break) is located on a 2020 sunset trail 291rk?
You're probably looking for this thing
google this string): RV Vacuum Breaker Check Valve | Protect Fresh Water from Pollutants 571-VAC-CHK-A
Shop around, prices vary.
Mine was located on the inside of the trailer opposite from where my black tank flush inlet (where my garden hose connects to my black tank).
Last winter the valve got stuck closed and would not allow water to fill/flush the black tank and of course the slinger would spin. I removed it (very easy, but difficult to get to the valve ).
I removed the vacuum breaker (photo below) I couldn't blow air into the inlet but the vacuum breaker did work when I sucked air at the inlet. I couldn't get air flow either direction at the outlet. (rinse it in alcohol or bleach before sucking on it).
It was very easy to disassemble the vacuum breaker/check valve. Turns out the check valve is a rubber ball (not plastic). It was "stuck" against the seat it rides against. It was stuck firmly enough it had the imprint of the seat into the ball. Not sure why or how that can happen. The "instructions" that come with a new breaker say not to leave it under pressure for more than 12 hours or the ball can get stuck. Water pressure from the inlet should move the ball forward away from the seat and compress the spring. For the ball to be stuck in the seat, by deforming the rubber ball, pressure would have to be coming from the black tank. I'm not sure how that would happen, but it did. I got the ball unstuck so re-installed it and it's been working fine since.
Here's a photo. Chances are you can un-stick it.
best of luck,
Dustin and Doris
2018 Crossroads, Sunset Trail 33CK,
38', 7600 lbs empty, 8300 lbs loaded.
2016 Tundra: 5.7L with towing package with added "Roadmaster Active Suspension"