Vacumn Leak

K-DUB said:
I just went through the exact same thing. Same symptoms. I threw so many parts at it I gave up and took it in. Long story short, they determined my hose is getting old and weak and it’s not holding shape well and hence loses vacuum. They adjusted the vacuum from 10 pounds to 9 pounds and it supposedly fixed it for now and bought another few years. (I have not picked the boat up yet to confirm)I will replace my hose this winter. Providing its working ok now.
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Exactly what hose are you talking about? The one that runs from the toilet to the vacuum pump?
Thanks
 
midexp said:
How can you check for a leak in the hoses if you disconnect them from the pump?
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You start at the pump and work your way towards the head. If the pump and accumulator cycle properly with the head hose disconnected.....then you connect the head hose to pump and accumulator and disconnect the hose at the head.

If it does not cycle properly with the head hose disconnected.....the hose is leaking. The key to solving a vacuum leak is patience and a vacuum test gauge.
 
midexp said:
Exactly what hose are you talking about? The one that runs from the toilet to the vacuum pump?
Thanks
Click to expand...
Correct. The way they explained it was the old hoses relax a lot and cause the pump to think there is a loss of vacuum.
I had never heard of adjusting the switch either, as well as recommending not touching them. I will evaluate more once I pick the boat up.
 
K-DUB said:
Correct. The way they explained it was the old hoses relax a lot and cause the pump to think there is a loss of vacuum.
I had never heard of adjusting the switch either, as well as recommending not touching them. I will evaluate more once I pick the boat up.
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I don’t think what they told you about the hoses “relaxing” is right at all unless they are talking about the clamped ends leaking air. 10 Hg does not cause an old hose to collapse.

What does happen is that waste hoses break down over time and can become permeable. A vacuum test will confirm it one way or another.

BTW the vacuum created has more to do with the effectiveness of the pump. If the pump does not create 10 Hg or more…..it will never trigger the switch.
 
PlayDate said:
I don’t think what they told you about the hoses “relaxing” is right at all unless they are talking about the clamped ends leaking air. -10psi does not cause an old hose to collapse.

What does happen is that waste hoses break down over time and can become permeable. A vacuum test will confirm it one way or another.

BTW the vacuum created has more to do with the effectiveness of the pump. If the pump does not create -10psi or more…..it will never trigger the switch.
Click to expand...

John, I'm betting you mean 10"Hg.
 
PlayDate said:
I don’t think what they told you about the hoses “relaxing” is right at all unless they are talking about the clamped ends leaking air. -10psi does not cause an old hose to collapse.

What does happen is that waste hoses break down over time and can become permeable. A vacuum test will confirm it one way or another.

BTW the vacuum created has more to do with the effectiveness of the pump. If the pump does not create -10psi or more…..it will never trigger the switch.
Click to expand...
They pulled the accumulator tank and pump, most of which I had replaced, and it bench tested it all to spec.
I am a bit skeptical as well, but if it works as it should I will be happy and will replace the hose over the winter.
 
Happy...once its done.
 
Best money spent on a tester:

upload_2023-6-18_15-56-43.jpeg
 
Catching up on this - yes I put new hoses in and used pvc on all straight runs to save money (the hose is nearly $20 a foot) and what I assume is a more durable long term solution.

The biggest bear was pulling out the heap of silicone in the engine room bulkhead to get the last bit of hose out. Job sucked all around though. I estimate a 40-45’ Sundancer needs around 80’ of hose to replace everything.
 
wow, really appreciate all the feedback. I changed the entire ball valve and the shaft. When I use the vacuum gauge, the leek seems to be from below since I pretty much rebuilt everything else, so I am pretty sure above the floor is ok. To check the vacuum when you remove the hose from the toilet to the accumulator tank you place the vacuum gauge at the elbow. If it holds vacuum it's the hose, if it doesn't it could be another bad vacuum switch. Both the local shop and Dometic told me they are having quality problems. Still need to replace the seal at the elbow, hopefully this week. I am keeping my fingers crossed this will solve the problem.
 
Bob,

I just am concerned about what they are telling you. If the pressure switch is bad.....that means it leaks air or the trigger mechanism isn't set right.

If the pressure switch is bad.....the pump and accumulator would not pass a bench test because it was leaking air or it didn't shut off at 10Hg. I can't think of another situation where the pressure switch would be "bad".

81vs76752NL._AC_SL1500_.jpg
 
Mine cycles for about 5 seconds every hour and I too have thrown a lot of parts at it. I am not too concerned other than it wakes me up sometimes since I sleep in the aft cabin/sofa.

I have replaced a hose before, in my previous Regal 3780, not fun at all. The hose ran from the forward head back thru the firewall, into the engine compartment, then back thru the firewall again, into the cabin bilge where the holding tank was.
 
I agree, I have now changed two pressure switches. The rubber donut at the elbow is white, the new ones from Dometic are black or at least that's what I am told. I now have a black elbow seal in my possession and will change it out and fingers crossed problem solved. When all this started, I could tap the pressure switch and it would stop the pump and hold vacuum. Now it will not stop at all, honestly, I am thinking another bad switch because I don't believe the elbow gasket is leaking that much or the hose is that bad.
 
K-DUB said:
I am also watching for feedback on hose replacement. I did one in my 270 20+ years ago and it was a bear to pull through. The 40 will be a lot longer pull.
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K-DUB, I replaced the sanitation hoses from both heads to vacuflush units, on the same boat that you have a few years ago. The forward and rear head hoses both have couplers. The forward head coupler is under middle floor hatch and the rear head coupler is under the aft cabin berth, starboard side.

Forward head hose path (port) from aft to forward is:

Vacu flush through bulkhead, and as Ryan states, silicone galore.

There is a chase (and cover panel) through the little closet in the aft cabin that leads to a sharp turn under the the cabin steps. The hose turns there again and exits into the 3 hatch area, near the shower sumps, then it’s a straight shot to the coupler. After the coupler, the hose goes a bit past the head door, takes another sharp turn and pops out in the head, under the toilet.

To replace, I used a barbed splicer adaptor to join the old with the new, used screws to secure the hose and wrapped with electrical tape, there is not enough room to pull clamps through.

This one was the hardest to do, took 3 of us. One in engine room to pull, one in aft cabin chase to push and me pushing under the rear most floor hatch.

Used the same method for the other 3 hose sections.
 
Sgrochow said:
K-DUB, I replaced the sanitation hoses from both heads to vacuflush units, on the same boat that you have a few years ago. The forward and rear head hoses both have couplers. The forward head coupler is under middle floor hatch and the rear head coupler is under the aft cabin berth, starboard side.

Forward head hose path (port) from aft to forward is:

Vacu flush through bulkhead, and as Ryan states, silicone galore.

There is a chase (and cover panel) through the little closet in the aft cabin that leads to a sharp turn under the the cabin steps. The hose turns there again and exits into the 3 hatch area, near the shower sumps, then it’s a straight shot to the coupler. After the coupler, the hose goes a bit past the head door, takes another sharp turn and pops out in the head, under the toilet.

To replace, I used a barbed splicer adaptor to join the old with the new, used screws to secure the hose and wrapped with electrical tape, there is not enough room to pull clamps through.

This one was the hardest to do, took 3 of us. One in engine room to pull, one in aft cabin chase to push and me pushing under the rear most floor hatch.

Used the same method for the other 3 hose sections.
Click to expand...
Sounds brutal.
 
Sgrochow said:
K-DUB, I replaced the sanitation hoses from both heads to vacuflush units, on the same boat that you have a few years ago. The forward and rear head hoses both have couplers. The forward head coupler is under middle floor hatch and the rear head coupler is under the aft cabin berth, starboard side.

Forward head hose path (port) from aft to forward is:

Vacu flush through bulkhead, and as Ryan states, silicone galore.

There is a chase (and cover panel) through the little closet in the aft cabin that leads to a sharp turn under the the cabin steps. The hose turns there again and exits into the 3 hatch area, near the shower sumps, then it’s a straight shot to the coupler. After the coupler, the hose goes a bit past the head door, takes another sharp turn and pops out in the head, under the toilet.

To replace, I used a barbed splicer adaptor to join the old with the new, used screws to secure the hose and wrapped with electrical tape, there is not enough room to pull clamps through.

This one was the hardest to do, took 3 of us. One in engine room to pull, one in aft cabin chase to push and me pushing under the rear most floor hatch.

Used the same method for the other 3 hose sections.
Click to expand...
Sgrochow, thank you for this information. It will prove invaluable when I go to do this job. It sounds pretty involved. I like the screw idea. I was already pondering how to hold the hose on the barbed fitting without the added hose clamp size restriction.
I picked up the boat on Sunday and all is working well for now. The test will be this weekend on a couple of overnights with the wife and two teenage girls. o_O
 
Well, changed the elbow seal to the new and improved black seal. Still no luck, however, same vacuum reading at the accumulator tank as the head so the good news is it is not the line. Removed the entire VG2 and dropped it off at the local shop. Fix it!! tired of messing around with it. He now thinks the only other item it can be is the gasket on the bellows. Stay tuned.
 
Just to close the story, it was the bellows again. Dometics quality has certainly gone downhill. I just replaced the bellows about a year ago.
 
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