Head vacuum problem

G

giangi

New Member
Jan 29, 2012
24
Ft lauderdale, FL
Boat Info
400 Sundancer 1997
Engines
Diesel Caterpilar
Hi guys:
I have a Sea Ray 400 Sundancer 1997 and I have a problem with the vacuum of the main head.
Pump keeps running and does not stop. No vacuum.
Mechanic changed the duck bills and checked for leaks and could not find any.
Tank was replaced a year ago. Checked the head and no leak there. Hoses look ok.
Does anybody had a similar problem? Any ideas are welcome.
Thank you
 
Probably the vacuum pressure switch.

Little switch on top of the tank that looks like a plunger. I think you can take the cover off and manipulate the switch itself using a screwdriver to see if the pump shuts off.
 
I’d probably just install a new pump or rebuild it. Cheaper to have replaced than having it rebuilt by a mechanic. If you do it yourself it’s not too expensive to buy the rebuild kit. New duck bills don’t fix the problem if the pump is shot and if it has been running for an extended time it’s likely shot.
Good luck
 
No vacuum means that the pump isn’t producing vacuum.

The duck bill valves are only part of the system. The bellows in the pump produces the vacuum. It and it’s seals within the pump body might be your problem.

When the pump is running, is there an odor in the bilge? If so, you either have bellows/seal issues of a leak at a hose connection.

Pour a pint of water in the bowl and run the pump for a minute or two. If you get a good pop and flush, the pump is producing vacuum. I’d then look at the switch on the tank.

No pop, no flush? Rebuild pump. Not a fun job and not one that always goes well, but a new pump is $600 and will need a rebuild itself in 5 years or so.

Check out a company called marine sanitation and supply.

Very helpful folks.
 
Soulshine said:
No vacuum means that the pump isn’t producing vacuum.

The duck bill valves are only part of the system. The bellows in the pump produces the vacuum. It and it’s seals within the pump body might be your problem.

When the pump is running, is there an odor in the bilge? If so, you either have bellows/seal issues of a leak at a hose connection.

Pour a pint of water in the bowl and run the pump for a minute or two. If you get a good pop and flush, the pump is producing vacuum. I’d then look at the switch on the tank.

No pop, no flush? Rebuild pump. Not a fun job and not one that always goes well, but a new pump is $600 and will need a rebuild itself in 5 years or so.

Check out a company called marine sanitation and supply.

Very helpful folks.
Click to expand...
Carpediem44DB said:
I’d probably just install a new pump or rebuild it. Cheaper to have replaced than having it rebuilt by a mechanic. If you do it yourself it’s not too expensive to buy the rebuild kit. New duck bills don’t fix the problem if the pump is shot and if it has been running for an extended time it’s likely shot.
Good luck
Click to expand...
 
A lot has been posted on this site on this subject. Suggest you do a search. It's important to isolate where the leak is before spending a lot of time and dollars on the various part of the system. It's easy to do-start by disconnecting the hose to the inlet elbow and installing a plug in the elbow-make sure it's sealed and if it then holds a vacuum then the problem is not in the generator but upstream, possibly in the toilet itself. If it does not hold a vacuum, then start with the elbow itself. The "Marine Sanitation" site is a good one. Call them and they can help. Do the search first.
 
I had a similar issue. The leak was where the pipe elbow goes into the tank thru a rubber grommet. The tank was slightly concaved and not sealing properly. Used 3m 4000 to fix it. I found it by spraying shaving cream around any spot I thought could be an issue. The cream gets sucked in so you know where the issue is.
 
That's right. The elbow is the first place I would look. They have redesigned the elbow and rubber gasket and it is very easy to replace. Again the guy at Marine Sanitation can advise.
 
We had a similar problem, but our pump kept running until the head system breaker would turn off. Our mechanical replaced the duck bill valves, checked everything as well, but still had the same problem. It ended up it was just a nasty clog before the tank. He had a hell of a time getting it un-clogged, but it solved the problem. Good luck!
 
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