Vacuflush Dometic Leak

[mark99]

Where can the vacuum leak from?

 

Mine wont keep a vacuum any more so I have replaced the cassete screw lids and the 4 O ring seals on the main toilet. Tightened up up eveything and checked the bowl seal. Flushed through loads pure water.

 

Its not the casette as it loses a vacuum whatever casette I use.

[jonesthenuke]

There are several places that the vacuum can leak, mainly on the O ring seals. For a start look at the large seals on the spout that enters the cassette (Clean and grease them , this may help). There is also the small spout where the air is pumped from the cassette. After that it could be the pump as the valves in the pump have to prevent back flow. I have also had a fracture in the pipe that is on the suction side of the pump.

 

Vacuflush toilets are easy to repair and you can get spare seals cheaply by purchasing O rings from Ebay etc rather than from Dometic or their agents.

 

If you search on here there are several posts on repairs, try searching for this as an example

Vacuflush toilet repairs By jonesthenuke,  September 8, 2016 in Boat Building & Maintenance 

 

Having sorted ours out last year the vacuum lasts for many hours (overnight?)

 

[jonesthenuke]

There are several places that the vacuum can leak, mainly on the O ring seals. For a start look at the large seals on the spout that enters the cassette (Clean and grease them , this may help). There is also the small spout where the air is pumped from the cassette. After that it could be the pump as the valves in the pump have to prevent back flow. I have also had a fracture in the pipe that is on the suction side of the pump.

 

Vacuflush toilets are easy to repair and you can get spare seals cheaply by purchasing O rings from Ebay etc rather than from Dometic or their agents.

 

If you search on here there are several posts on repairs, try searching for this as an example

Vacuflush toilet repairs By jonesthenuke,  September 8, 2016 in Boat Building & Maintenance 

 

Having sorted ours out last year the vacuum lasts for many hours (overnight?)

 

Edited to add:- Just to be clear,  you have changed the seals on the toilet, does the water level stay in the bowl? 

[blackrose]

Remember to use silicone grease.

 

I serviced mine (for the first time in 13 years!) last year using the jonesthenuke's advice, and although I tried to service the cassettes that didn't work so I bought 2 new ones. 

 

It's a lot better now but the motor still cycles after 5 mins and LeeSan did a little test with me over the phone where I took the cassette off and blocked one of the holes with my finger. They told me that the I needed to take the motor off the back and replace the seals on that too. 

 

I haven't done it yet. I just switch the toilet off when I'm not using it.

Edited July 1, 2018 by blackrose

[pearley]

It's not so much the seals in the pump but the non return valves that leak. If bits of crud get under them then the pump will cycle. The test that Blackrose mentions is to remove the cassette, block the hole in the vacuum tit (left of centre at top of docking station, under the grey latch if you have one) then press and hold in the micro switch bottom right.. The pump should run for a couple of seconds then stop. If it then recycles you know you need to strip and clean the pump. I have instructions with photos if anyone wants them. 

Edited July 1, 2018 by pearley

[mark99]

Cheers guys. I do suspect the pump as all other o rings have been replaced with genuine manufacturers o ring spares and greased. It's been fantastic for years holding a vacuum for days/weeks. Now the pump cycles perhaps every 3 or 4 hours. We switch off as mentioned and use as and when.

Edited July 1, 2018 by mark99

[blackrose]

7 hours ago, pearley said:

It's not so much the seals in the pump but the non return valves that leak. If bits of crud get under them then the pump will cycle. The test that Blackrose mentions is to remove the cassette, block the hole in the vacuum tit (left of centre at top of docking station, under the grey latch if you have one) then press and hold in the micro switch bottom right.. The pump should run for a couple of seconds then stop. If it then recycles you know you need to strip and clean the pump. I have instructions with photos if anyone wants them. 

That would be useful Pearley if you want to post them here or PM me please?

[BWM]

I had this problem on a previous boat with a Lee sanitation pump out version, this was due to the non return/duck bill valves being either fouled or defective. 

[Dr Bob]

4 hours ago, BWM said:

I had this problem on a previous boat with a Lee sanitation pump out version, this was due to the non return/duck bill valves being either fouled or defective. 

On the pump out version, putting a bowl full of hot soapy water cleans the duck bill valves. Lee San advised us to do this once a month and this sorted a sticking duck bill valve on ours. Not sure you could do this on the cassette version. 

[jonesthenuke]

15 minutes ago, Dr Bob said:

On the pump out version, putting a bowl full of hot soapy water cleans the duck bill valves. Lee San advised us to do this once a month and this sorted a sticking duck bill valve on ours. Not sure you could do this on the cassette version. 

This will not help on the cassette version as the liquid would not pass through the pump. 

 

The pump is simple enough to take apart and clean. The valves are simple rubber flaps so turning them over helps if they are worn