390 Motoryacht. 2005. Vacuflush System

[Rob Jacobson]

My Vacuflush system for the master head pumps continuously, no water is leaking from the head. Read earlier might be the duckbills? If so any idea what part number to order and is they a video showing how to replace? Thanks. Rob

 

[Lazy Daze]

There is, literally, a crapload (see what I did there?) of information on this forum and the internet about how to change the duckbills - googling will return many results and videos. But, the reality is, that it's very straight forward - basically just remove and replace. Yes, they are the most likely cause - although you could have a torn bellows pump - you'll be able to check it out easily, though. The only thing you need to verify is whether you have 1.5" or 2" duckbills. I don't want to guess - but you can look in your parts manual (or download it) or just go look at what size the hose is. Once you know the size - that's it - you don't need a part number or anything fancy like that. If you order from a reputable place, it will likely even come with instructions... although you'll have to "read" those...

 

[Mark.60]

If the system builds pressure and flushes but the pump continues to run chances are the pressure switch is bad. I had that on my 33 sundancer. I changed all duck bills ,rebuilt the pump and didn’t fix problem until I replaced switch. Good luck

 

[alnav]

I think the 390/40 MYs all have the larger duckbills. It could also be an air leak between the head and the pump. Mid-2000 vintage boats seemed to have lots of sanitation hose problems; I've had to replace both of mine. I learned the hard way to test for this before starting to take apart the pumps. Take the hose off the vacuflush pump inlet. Block the inlet (your hand will work) and have the pump turned on. If the pump stops and holds vacuum then the air leak is before the pump. Changing out the hose from the master is very easy, the one from the guest head not so much.

 

[Rob Jacobson]

Thank you all for the advice, I’ll look for the air leak first and the hoses are 2 inches

 

[Lazy Daze]

Another thing you can do to check for a leak is to just listen. Let the pump do it's thing for a few minutes then shut everything off and listen closely. Sometimes you'll find a brittle sealing grommet or something. Adding to the point about the pressure switch... sometimes you can play with it a bit (put a little pressure on the spring/post) and you can get it to cause the pump to turn off - which would help in diagnosing.