henderson Pump

[30boat]

The Henderson pump in my Lavac head insists on leaking from the lower part of the joint despite having had new rubbers fitted last year .Tightening the bolts to a reasonable degree doesn't seem to help and the mating surfaces seemed alright when I last looked.
Is this normal with these pumps?This particular one is probably quite old but it appears to be in good condition.
Thanks

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[HeadMistress]

I ran into a similar situation on a consulting job recently...3 boats, all fitted with Henderson pumps (MK5, same one used by Blake for the Lavac)...they'd all leaked around the tailpiece connections. The yard's solution was sealant...but I dunno if that's really necessary. It's possible that over-tightening the bolts caused the rubber gasket to pucker, which would cause it to leak. So try loosening the bolts a little--tight enough to get a good seal, but not enough to depress the gasket any at all.

If that doesn't work, have a chat with Henderson. You said the pump is quite old...it could just be time to rebuild it.

<hr width=100% size=1>Peggie Hall
Specializing in marine sanitation since 1987

 

[AndrewB]

Mine started to leak quite badly when I fitted a holding tank, which I attributed to the extra pressure associated with all the additional pipework and valves. After the holding tank and pipework was removed, it stopped. However, there was again some slight leaking last season, so after 15 years of constant use, finally I have just replaced it.

From my experience - check there are no constrictions being caused by excessive scaling, particularly at the pump valves or the seacock. A smear of Vaseline around the edge of the diaphragm before reassembly definitely helped for a while, but probably wasn't a long-term solution. Sometimes slight weeps will take up themselves if left alone. However, it seems to me like a design weakness that the diaphragm is held in position by the outer part of the pump body.

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[jerryat]

Hi Headmistress!

I agree with you re over-tightening of the bolts. We've used our Lavac/Henderson combine for the last 15 years (the pump's 20 years old) and 'full time' whilst cruising for the last 7 years without any leaks whatsoever.
However, the pump is removed, stripped down and thoroughly cleaned twice a year. The inlet and outlet pipework is also removed and 'banged out' at the same time.

The calcium(?) build up is astonishing and if left, seriously reduces the efficiency of the unit and very much increases the pressure needed to operate the pump. We've tried all sorts, vinegar flush through, Blakes seacock grease on all internal surfaces etc etc, but there is, unfortunately, no substitute for preventative maintenance.

I also connected a holding tank and it's associated pipework with no problems, BUT, did note that had I run the pipework as I'd originally intended, it would have put a twisting stress on the connections. This might well have distorted the outlet over time, and I re-routed to avoid this - I can't think of a worse job if a repair has to be carried 'in anger'!!

I have replaced 2 joker valves, 1 flap valve and 1 diaphram during this period and ensure that, when re-assembling, the bolts are tightened diagonally in rotation as you would an engine cylinder head. The bolts need minimal tension but many seem to crank them up so that the diaphram sqeezes from the joint, almost always unevenly which could also lead to distortion of the pump body. I find it difficult to believe that mastic would form a cure, certainly not long term.

Hope this helps.

Good sailing!

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[philip_stevens]

Talk to
Munster Simms Engineering

(028) 91270531

Sales Wks, Old Belfast Rd
Bangor
BT19 1LT

They make the Henderson Mk5, and could give you makers advice.


<hr width=100% size=1>regards,
Philip

 

[heerenleed]

Thank you for all this information. The leaking problem when replacing all the rubber components of our Henderson pumps for our two lavacs ALWAYS resulted in them leaking. Probably I overtightened the bolts. Won't do that ever again....

cheers

<hr width=100% size=1>Peter a/b SV Heerenleed, Steenbergen, Netherlands
<A target="_blank" HREF=http://www.heerenleed.tk>http://www.heerenleed.tk</A><P ID="edit"><FONT SIZE=-1>Edited by heerenleed on 04/05/2004 08:43 (server time).</FONT></P>