Vacuum switch for Dometic/Sealand VG2 ...can't find stock anywhere

[YeOldeStonecat]

I had replaced my 4 duckbills and the bellows for our VG2 system over a month ago.
At first, seemed to work fine except the vacuum generator pump ran double the time, sometimes over 60 seconds. And then more...and more.
Eventually just didn't stop running.
I pulled the plumbing to get to the duckbills again this weekend, cleaned them, regreased, tried putting back just hand tighten...and system just isn't happy. Flushing toilet....often not much "vacuum" sucking that water out.

I removed the vacuum switch, the backside...had a collection of rust/corrosion. There's that large...round metal plate, seems to be bedded onto a rubber diaphragm behind it. The lower edge of that round metal plate was corroded and rough edges. I'm thinking it created a hole in that rubber seal....or some crude behind it? Can't see.

Anyways, specifically I'm looking for item 13 on this page...

https://marinesan.com/vacuflush/vacuflush-pump-generator-parts-diagrams/vg2-12-24/

They seem to be out of stock at marinesan.

 

[YeOldeStonecat]

Doing some more checking on it.....I hear a sorta "hiss" sound by the bellows (which I replaced last month with the main kit that included the gaskets and duckbills).

I've read a few people mention that the gasket for the bellows is difficult...so maybe I screwed that up.
Wonder if I can pull the top off....while the unit itself remains attached to the vacuum generator box...without "water/stuff" from the uphill hose to the black water tank gushing up and out of that bellows/piston hole. Hoping I can just reset those c-clamps and gasket around that without having backflow come out.

 

[Captsteve427]

Doing some more checking on it.....I hear a sorta "hiss" sound by the bellows (which I replaced last month with the main kit that included the gaskets and duckbills).

I've read a few people mention that the gasket for the bellows is difficult...so maybe I screwed that up.
Wonder if I can pull the top off....while the unit itself remains attached to the vacuum generator box...without "water/stuff" from the uphill hose to the black water tank gushing up and out of that bellows/piston hole. Hoping I can just reset those c-clamps and gasket around that without having backflow come out.

I found a vacuum switch on line for my vg4 a couple of weeks ago at the below marina. I think it may be the same as your vg2. Maybe they have more stock.
https://www.ess-kayyards.com/

 

[ttmott]

Doing some more checking on it.....I hear a sorta "hiss" sound by the bellows (which I replaced last month with the main kit that included the gaskets and duckbills).

I've read a few people mention that the gasket for the bellows is difficult...so maybe I screwed that up.
Wonder if I can pull the top off....while the unit itself remains attached to the vacuum generator box...without "water/stuff" from the uphill hose to the black water tank gushing up and out of that bellows/piston hole. Hoping I can just reset those c-clamps and gasket around that without having backflow come out.

I have the VG4 generators but that bellows configuration is the same.
The trick is to put silicone grease on that item 4 O-Ring and install the O-Ring into the bellows; not on the plastic cover.
Then work the bellows/O-ring onto the cover. Rotate it so that bolt will align with the motor then install the two collars and slide the cover assembly into the housing. If you try to first install the bellows into the housing and try to install the cover with that O-Ring on the cover it will not insert into the groove in the bellows and assuredly leak.

 

[carterchapman]

I have the VG4 generators but that bellows configuration is the same.
The trick is to put silicone grease on that item 4 O-Ring and install the O-Ring into the bellows; not on the plastic cover.
Then work the bellows/O-ring onto the cover. Rotate it so that bolt will align with the motor then install the two collars and slide the cover assembly into the housing. If you try to first install the bellows into the housing and try to install the cover with that O-Ring on the cover it will not insert into the groove in the bellows and assuredly leak.

Another Home Run Tom!! Great advice!

 

[YeOldeStonecat]

Gave MarineSan another call this morning...she said she had a handful on stock (that she doesn't always update the website if there's only a couple). So they're on their way. Got another o-ring/gasket set too, and TTMOTT...thanks, I'll pull the piston/bellows apart again and redo that.

This past weekend while re-doing the duckbills, the "out" hose from the pump...goes uphill for about 3 feet to dump into the top of my blackwater tank. Normally can shut off the water and let the vacu pump run for a minute or two to push "most" of the....err...water...up and out of that hose. So when I remove the hose...not much stinky water runs out...I put plastic bags under to catch it. Well, the pump wasn't making much (guess that gasket really got worse)....so...when I went to pull that hose, so much came pouring out..the plastic bags side just push out...and..ugh....gallon of dinty more stew all over that bilge area. My poor shop vac! Could have heard me cursing for miles away....

 

[330DA]

YeOldStoneCat,
I, too, had the same issue with the pump cycle times being anywhere from 4 mins to over 8 mins and sometimes more over the past 3+ seasons. I changed the duckbills, vac sensor switch, pump, bellows. My Sea Ray service dept also changed the duckbills. Then end of last year, the Service Mgr said the duckbill mfg started to make them more oval and they had customers whose duckbills slipped out of wack. This year, before launch they checked them and found one had to be reset.

The first day using the head it went from taking more than 10 mins to stop pumping to not stopping. I had to turn the breaker off to stop it. Then it had no vacuum at all.

The Service Mgr had the Tech pull the vac tank and bring it to the shop to check everything out. The VG2 has the pump and bellow mounted on top of it.

Well, the vac tank was full of old toilet paper!!! I’ve had this boat 4 years and the head issue just got worse and worse. It only got better (pump cycle time) each time I replaced something and then back to 7+ mins pumping. The prior owner must have not used marine TP. The system was plugged up.

Cleaned the vac tank out and they reassembled everything. Amazing!!! It now cycles and turns off in about 25 seconds!

 

[Deep in Depth]

Dometic tells me the VG2 should create enough vacuum to turn the pump off within 60 seconds. Anything better is a bonus.

 

[YeOldeStonecat]

So....back at the boat. Replaced the vacu switch. Also replaced the 2x gaskets on the bellow pump.
She stops pumping in like...15 seconds.
When you flush the toilet, it's like there is only ....mild vacuum. Toilet flushes rather quietly, like there is not much suction. Normally when flushing it was like a "pop" loud vacuum suction. Now it's a gentle....the water falls down the toilet. Afraid wife will go #2 and it won't get pulled down.

When flushing the toilet, bellows pump goes for about 15 seconds, maybe even 12...shuts off...and we might hear it cycle again in 20 minutes or 30 minutes for about 5 seconds.

It seems that the new vacu switch is shutting off before it builds up enough vacuum.