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Old 10-09-2012, 03:06   #1
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A Question for Lavac Owners

Hi There,

I have a Lavac head, installed without the little plastic breather thing on the "flushing water" pipe, as described in the manual it should be there, also it was pretty grimy inside the pump when I bought the boat ... it has had multiple flushings with acid, and is looking cleaner and operates better now ...

But I have a few questions ... is it normal for flushed water to drain back into the head? And/or is it normal for the head to be filled with water up to the rim after the vacuum releases. Because I find that after flushing and the vacuum releases I have a toilet full of water, and sometimes it is a little off-colour.

Obviously I am considering rebuilding the pump, and installing the plastic breather, as per the manual ... but I wanted to ask if this is normal?

Cheers
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Old 10-09-2012, 03:37   #2
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Re: A question for Lavac owners

no and no

the reason the bowl is filling is the duck valve on the hand pump on the outlet side is faulty and letting water flow back.

also it is possable that the water on the inlet side is siphoning,this you need to sort out as well as it could sink the boat if you do not close the seacock.

to empty the bowl if it is full after pumping,you need to lift the lid to break the vacume,and continue pumping till it is empty.
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Old 10-09-2012, 03:50   #3
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Re: A question for Lavac owners

ahhhh ... I suspected it wasn't right, and that makes sense.

one more question ... is the duck valve serviceable? or is it a "just replace the thing" exercise? If serviceable, can you give me a quick hint as to what's involved?

Thanks
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Old 10-09-2012, 03:57   #4
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Re: A question for Lavac owners

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Originally Posted by jannw View Post
ahhhh ... I suspected it wasn't right, and that makes sense.

one more question ... is the duck valve serviceable? or is it a "just replace the thing" exercise? If serviceable, can you give me a quick hint as to what's involved?

Thanks
no if it is a duck valve it will be torn or inside out,or it may be a flappper,depending what type of pump you have.

if it is the standard pump with the bit that opens,spares are easy to get here in the uk,i forget the make,but most online chandelery will be able to supply.

if you have trouble getting spares it is worth noting that any hand operated bilge pump with the same diam tube outlets will work.

part no 28 is what you want in the pump diagram

http://www.blakes-lavac-taylors.co.uk/pdf/lavac.pdf
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Old 10-09-2012, 08:19   #5
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Re: A question for Lavac owners

Thanks ... that's helpful ... J
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Old 10-09-2012, 08:42   #6
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Re: A question for Lavac owners

The stock pump is a Henederson Mk V, which is the same as a Whale Mark V. It's a very common rebuild kit and quite easy to do. Here's the rebuild kit on Amazon if the OP is in the US.


Amazon.com: Mk5 Universal Manual Pump Spares Kit Henderson Mark V: Sports & Outdoors
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Old 10-09-2012, 08:56   #7
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Re: A question for Lavac owners

First you NEED the vacuum break 'hole' in the top of the inlet hose. The size of the hole determines how long water keeps flowing into the bowl AFTER you stop pumping WITH THE SEAT CLOSED TO CREATE THE VACUUM...

without this you'll go into siphon mode and can literally sink your boat unless you close the seacock after every use or at best get a full bowl as you do now..

How high above the head is your pump? Any and all water in this line between the pump and the head will flow back into the head when you stop pumping...Just like a bilge pump. How high is the highest point in the discharge line in relationship to the bowl? There is no, and should not be, any one way valve in the system between the bowl and the pump...

Do you have the Henderson pump?
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Old 10-09-2012, 11:31   #8
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Re: A Question for Lavac Owners

yep ... got the henderson pump, and going to order the anti-siphon break.

And the pump is about two feet /60 Cm above the toilet bowl ... so perhaps it is just the gravity back flow, and I need to do more pumping!

Looks like the order of the day is to install the anti-siphon, and rebuild the pump ... and see what happens then.

Thanks,

J
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Old 05-01-2016, 03:37   #9
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Re: A Question for Lavac Owners

How is the Lavac working out?

I'm contemplating switching to Lavac Popular from a RS-69 (which leaks and has been unreliable).
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Old 05-01-2016, 12:48   #10
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Re: A Question for Lavac Owners

I love our Lavac, my wife not so much. We have a manual Lavac. Pretty much maintenance free. No o-rings, no joker valves, and no lubricating. It's just a little different to use, which is why the wife doesn't like it as much. She's pretty much gotten used to it, though.


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Old 06-01-2016, 01:59   #11
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Re: A Question for Lavac Owners

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Pretty much maintenance free. No o-rings, no joker valves, and no lubricating.
That sounds like heaven! (which isn't something you often say about marine toilets)
How old is your Lavac? I've read that some people have problems with the new Lavac pumps not being as good as older ones. Though after reading a few threads I get the impression that in many cases the problems stem from faulty installs.
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Old 06-01-2016, 09:40   #12
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Re: A Question for Lavac Owners

Ours was put in when the boat was built, 1999. It's a manual pump, so the pump is just a Whale Mark V. It works great, just takes a little to get used to.Click image for larger version

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Old 06-01-2016, 21:21   #13
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Re: A Question for Lavac Owners

Admiral & I never liked those marine toilets, sailing weight sensitive catamarans we just made our owns. Little carbon fiber, epoxy, 2 mark V pumps, breather, 2 diverter valves (toilet/shower-sump/holding-tank) and all plumbing hidden, waterline level in bowl is same as boat & as you see. No additional check valves, there are 2 in the mark V.

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Old 06-01-2016, 21:27   #14
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Re: A Question for Lavac Owners

6 years in service now and never needed any service, never stuck with paper or other undigested debris. Those pumps are great. Sea water in our marina is very dirty, we flush open cover with sweet water, sailing cover closed, using seawater. The transparent cover helps a lot to see, in our case this was leftover from our windows. For me these vacuum toilets are the only way to go.

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