vacuflush troubleshoot - 2000 sundowner 285

deraeler

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Jul 10, 2019
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Unit won't flush, suspect a clog or duck bill valves...no blown fuses. I have a vacuum holding tank (VHT) unit in the engine compartment that has what looks like a pump on top of it. However from what I've read there's supposed to be a vacuum pressure tank and associated tank between it and the toilet. I've looked as far as I can under the deck sink forward towards the head area and I can't see anything but the waste hose. Does anyone know where the vacuum unit is located? OR is that VHT an "all-in-one" type of unit?

What I've read tells me to look for three components - toilet, vacuum tank/pump and the holding tank. The VHT has the hose connection leading to the dock pumpout outlet on the gunwale, and the waste hose inlet. It's definitely THE waste holding tank.

I can't find a layout of these boat components online. I've removed the TP holder in the head and can only see the head sink outlet thru the hull. No sign of a vacuum pump/tank back there. Would it be UNDER the toilet??? along with a bellows assembly perhaps?

Help! I know I have an ugly job ahead of me, but I cant even get started until I can find all the components!

I could post a pic of the VHT if that would help. It's a VHT12. Even the manual shows a separate vacuum tank/pump assembly as well as a filter unit (for air I believe) - but I cant find these anywhere. Toilet is a model 508+ (Sealand/Dometic),
 

alldodge

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The VHT-12 is an all in one system, meaning the tank and pump are together. Many have separate units but this is an all in one

VHT12-diagram.jpg
 

deraeler

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Jul 10, 2019
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cool, that's what I was presuming, thanks for the confirmation.

I also see no discharge pump for the overboard discharge, I've only had pumpouts done thru the gunwale / dockside discharge.

It's very odd - I winterized it correctly and it seemed fine. Flushed a couple of times then acted like it was full. Had it pumped out. Then again, flushed fine a couple of times, then acted full. I again had it pumped out, this time the hose was transparent so I could see only 1-2 gallons of liquid pumped out at most. Used it once or twice then it just stopped flushing altogether.
Bowl will fill with water but wont empty.

I'm going to try a shop vac from the toilet with the waste hose disconnected at the VHT.

I hear the pump mountings usually are too corroded to remove the pump (boat is a 2000 Sundowner ) so the whole VHT usually has to be replaced. Hoping to avoid that of course. Will soak those pump mounting bolts in PB Blaster for a day or two and try to get the pump off for examination if the vac doesnt do anything -

Any insights appreciated!
 

alldodge

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Most don't have side discharge capabilities. Its illegal in fresh water lakes and some areas of the great lakes. Some rivers its ok, but would always need to check.

Do try to get all the pressure bleed off before you start working on it, there have been many which wound up taking a bath when they didn't. friends have worked on them and have had some issue with pressure

I have not worked on one and mine has never had an issue.
 

deraeler

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Jul 10, 2019
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Forgive me for not following up, I lost track of this post, but am very grateful for the help - it was very useful to help me understand the system. Fortunately I identified loose wiring as the cause...firmed up the connections and it started working - found the fault by accident when preparing to remove the unit...lol....a rare save by the Man above... :).
 
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