2019 NP 377RLBH Black Tank Draining

[prm99v6]

When I drain the blank tank I have a “glug” like pouring something out of a bottle. To me this means that the vent is not functioning as it should and it is sucking air.

Does anyone else with a 377 have this problem?don’t know it it’s common (caused by poor design) or limited to me and I have some obstruction in the vent stack.

Thanks

[Dskyward]

Originally Posted by prm99v6

When I drain the blank tank I have a “glug” like pouring something out of a bottle. To me this means that the vent is not functioning as it should and it is sucking air.

Does anyone else with a 377 have this problem?don’t know it it’s common (caused by poor design) or limited to me and I have some obstruction in the vent stack.

Thanks

That is strange. We have a 2017 377 and ours don’t do that. Try filling the black up completely and then do a drain. Get a clear elbow for both ends of the septic hose to see what’s happening. You can also get up on the roof and check to make sure the cap isn’t obstructed. Otherwise, a trip to the dealer is in store.

Another test is to fill the bowl full up to he brim and flush. How fast does it drain? Is there a large bubble or several trying to cough back up at you? If so, you have a vent problem. Sometimes we hear of the plastic circle cutout falling back into the tank at the factory when they drill and install, and that can get lodged at the drain valve, slowing the flow dramatically.

[Jace817]

Mine doesn’t “glue” but it is much slower than my previous BHBE on both the gray and the black. The gray is especially slower. Guess it has more turns.

[prm99v6]

Originally Posted by Dskyward

That is strange. We have a 2017 377 and ours don’t do that. Try filling the black up completely and then do a drain. Get a clear elbow for both ends of the septic hose to see what’s happening. You can also get up on the roof and check to make sure the cap isn’t obstructed. Otherwise, a trip to the dealer is in store.

Another test is to fill the bowl full up to he brim and flush. How fast does it drain? Is there a large bubble or several trying to cough back up at you? If so, you have a vent problem. Sometimes we hear of the plastic circle cutout falling back into the tank at the factory when they drill and install, and that can get lodged at the drain valve, slowing the flow dramatically.

Thanks. The bowl flushes fine and when the black tank is full it seems to come out good. But once it gets lower there is the suck of air , the “glug” then good flow then it slows and repeats the cycle until it’s empty. I’ll get up on the roof and check the vent stack.

[JohnWedell]

I had a problem Like that with a Montana fifth wheel. What I did was remove the vent cap take a tape measure and measure from the top of the roof to the bottom of the tank recorded that number, then slowly pulled up the tape until I contacted the bottom of the vent pipe that will give you the distance that’s in the tank. If the tank is for instance 8 inches and you only have 4 inches in the tank the vent went to far down and that’s the problem.

[Dskyward]

One way to test the vent theory is to empty the black tank completely, get several 5 gal buckets, full 1” below brim, carry up the steps carefully, and count how much goes in til the drop tube starts to fill. Or with a garden hose and cutoff valve, fill one at a time in the bathroom. Keep tabs how it acts as you approach the 40 gal mark (8 buckets). You should have a 50 gal black tank.

As a side note, however, our shower grey is listed at 50 gallons, and I’ve measured 67 gallons on one experiment. I’ve pictures and video at the factory tour which shows both tanks looking equal size.

I carry 6 five gal buckets and lids with as our makeshift ‘blue caddy,’ but ONLY for draining grey water! 30 gal of capacity and stores much easier (3 on each basement side) costs much less. $3/ea at WM. Lids are $1.50/ea. All for $30. If you can lift 43 lbs into the pickup bed, it’s a viable alternative, and a good workout since we fulltimers don’t ever hit the gym.

[Fire_Instructor]

If you are near full and it "glugs", but then stops "lugging" as the tank continues to drain, it's a sign that the vent has been pushed too far into the tank. Fill the tank with water, have someone step on the toilet flush (to let air in), and drain. If there is no "glug", then the vent is too deep in the tank.

[oldmanAZ]

Originally Posted by Fire_Instructor

Snip...
have someone step on the toilet flush (to let air in), and drain. ...snip

Doh An excellent way to check vent restiction issues! Thank you!

[prm99v6]

Originally Posted by Fire_Instructor

If you are near full and it "glugs", but then stops "lugging" as the tank continues to drain, it's a sign that the vent has been pushed too far into the tank. Fill the tank with water, have someone step on the toilet flush (to let air in), and drain. If there is no "glug", then the vent is too deep in the tank.

I think it’s when it is lower. I have to check, but definitely want to check this. Thanks!

[Stevek10]

I have the same problem with mine. Keep me posted, its annoyingly slow and I feel it slows down the sanicon system because that discharges faster than the black tank drains.

[Dave A]

Originally Posted by Jace817

Mine doesn’t “glue” but it is much slower than my previous BHBE on both the gray and the black. The gray is especially slower. Guess it has more turns.

I noticed the gray tank being slow also and checked into it. It has a maybe a 1 1/2 inch pipe draining from it into the larger 3 inch drain pipe. Can't imagine why they did that. I've started draining both gray tanks at the same time to make things go a little faster.

[Dskyward]

Originally Posted by Dskyward

One way to test the vent theory is to empty the black tank completely, get several 5 gal buckets, full 1” below brim, carry up the steps carefully, and count how much goes in til the drop tube starts to fill. Or with a garden hose and cutoff valve, fill one at a time in the bathroom. Keep tabs how it acts as you approach the 40 gal mark (8 buckets). You should have a 50 gal black tank.

As a side note, however, our shower grey is listed at 50 gallons, and I’ve measured 67 gallons on one experiment. I’ve pictures and video at the factory tour which shows both tanks looking equal size.

I carry 6 five gal buckets and lids with as our makeshift ‘blue caddy,’ but ONLY for draining grey water! 30 gal of capacity and stores much easier (3 on each basement side) costs much less. $3/ea at WM. Lids are $1.50/ea. All for $30. If you can lift 43 lbs into the pickup bed, it’s a viable alternative, and a good workout since we fulltimers don’t ever hit the gym.

Update correction: just discovered my 5 gal values above are not accurate on the Wally World 5 gal pales I’ve been using. Actual 5 gal mark is at the top rim, about to spill over...not 1” or so below as I presumed. The 4 gal mark is exactly 2.5” from top rim, so 1” below is app 4.5 gal. Therefore my shower and kitchen grey tanks are not as larger as thought. Probably closer to as advertised. My apologies if I lead anyone astray.