Triple clog in black water drain

[Abinition]

In the black water drain system, everything stopped working; the black water pump won’t turn on, the manual lever downstream of that is pretty frozen solid and does not pump and finally the thru hull value downstream of that is also frozen (in the open position) and I’m afraid to exercise it for fear of breaking. Seems like some kind of obstruction has occurred that has all three means of pump-out non-operational.

I’m completely new to trawler maintenance. It’s a Nordhavn 2006 47. She is otherwise well maintained.

Ideas? Thanks.

 

[RT Firefly]

Greetings,
Welcome aboard. The three issues may not be from the same cause but simply a lack of exercise of the valves. How freely do the rest of the valves/thu-hulls operate?

 

[mvweebles]

Is there a schematic of the head system in whatever documentation you have? Nordhavn usually provides decent information - there are a number of ways to plumb a head/tank/overboard discharge.

I'm a bit confused by the description - there is often a Y-Valve (sometimes two) to select outflow to holding tank, overboard, or pump out. Normally, the macerator pump is downstream of any Y-Valve and goes directly to the overboard thru-hull, but that's not the sequence you describe.

At any rate, first thing I would check is to do a diagram of the system and where the valves are located. Can you empty the holding tank via a pump out station? Is there power to the macerator pump?

Maybe others have ideas on frozen valves. BTW - is the midstream valve plastic or metal?

Sorry for your troubles.

Peter

 

[backinblue]

The way I read the description is that the head empties to the holding tank. There is both an electric and manual pump leading from the holding tank to a thru hull for overboard discharge, which is his description of "pump out". My boat is plumbed the same way with the exception of no manual pump.

 

[PM]

I am going to guess, grease. Liquid when warm, as it gets cooler, like close to the tank, and especially the discharge end it gets downright solid.

Personally I wouldn't attempt to clean out the lines. Replace them.

pete

 

[Abinition]

The way I read the description is that the head empties to the holding tank. There is both an electric and manual pump leading from the holding tank to a thru hull for overboard discharge, which is his description of "pump out". My boat is plumbed the same way with the exception of no manual pump.

Yes your rephrasing of my description is correct. Thank you

 

[Abinition]

I am going to guess, grease. Liquid when warm, as it gets cooler, like close to the tank, and especially the discharge end it gets downright solid.

Personally I wouldn't attempt to clean out the lines. Replace them.

pete

Interesting theory. This is Southern California so it’s not too cold at the moment. Agreed I’m hesitant to clean out anything stinky. I’m 100 yards from Nordhavn headquarters so they will point me to some expert. Plus I just bought the boat thru them. Survey did not state a problem so this is all quite a surprise.

 

[Comodave]

Interesting theory. This is Southern California so it’s not too cold at the moment. Agreed I’m hesitant to clean out anything stinky. I’m 100 yards from Nordhavn headquarters so they will point me to some expert. Plus I just bought the boat thru them. Survey did not state a problem so this is all quite a surprise.

Welcome aboard. Most surveys will miss some things. All used boats have some sort of issues.

 

[Comodave]

In the black water drain system, everything stopped working; the black water pump won’t turn on, the manual lever downstream of that is pretty frozen solid and does not pump and finally the thru hull value downstream of that is also frozen (in the open position) and I’m afraid to exercise it for fear of breaking. Seems like some kind of obstruction has occurred that has all three means of pump-out non-operational.

I’m completely new to trawler maintenance. It’s a Nordhavn 2006 47. She is otherwise well maintained.

Ideas? Thanks.

You say the black water pump won’t turn. I assume you are referring to the macerator. Some macerators have a slot in the shaft on the back of the pump. Try putting a straight slot screw driver in the slot and wiggle the shaft back and forth. Macerators don’t get used often and will sometimes freeze up. Working the shaft back and forth will sometimes break it loose and it may start working.

 

[backinblue]

I agree that a surveyor may not bother to try running the macerator especially if it's illegal to do so. I don't remember the surveyor doing that on my boat either. However, be happy it wasn't a bigger miss. I ended up having to replace my holding tank due to a crack in the top of it near one of the hose fittings. If you end up having to replace some hoses and/or a pump, write it off as part of the joy of new boat ownership. There will undoubtedly be more.