"IanM" wrote in message
...
Capt. JG wrote:
"Frogwatch" wrote in message
...
My Yanmar 2GM was overheating because I could not get sufficient raw
seawater to flow through the heat exchanger. I cleaned the exchanger,
cleaned all lines leading to and from it, cleaned the raw water
strainer, cleaned growth from the water intake. I was able to blow
air thru from the top of the intake to verify it had no blockage. It
would start to pump and then soon be only a trickle. Replaced the
pump impeller twice too. WTF?
Finally, after months of screwing with it, I took off the raw water
seacock (problematic cuz she is in the water) and between the seacock
and hull fitting, found a piece of shell that would act as a one-way
valve when it got sucked into the seacock. I could blow downward thru
it no problem and it would initially flow upward too but it would then
lodge in the seacock blocking it.
SO, if you have raw water flow problems, you might check for this.
That's a interesting problem. How did it get past the screen (I'm
assuming you have one?) at the hull where the thru-hull comes, err,
through? I've not had it happen yet, but I could imagine a plastic bag
getting trapped on that screen. The only two ways to remove it would be
to either stop the engine and hope the plastic fell away or visit it
personally.
I have a vertical type strainer directly on a ball valve seacock with no
external screen. Its 1/2" bore so a length of 10mm dowel might come in
handy. I'd get some water inflow, but nothing I couldn't cope with holding
a sponge in the other hand. I think the recommended solution for plastic
bags is blow back down it with a dinghy pump. Worst case, I have enough
hose on board to rig something from another intake.
I guess a dinghy pump might work... still have to shut off the engine. It
would increase the potential for a sinking, but I'm wondering if there are
any sailboats with redundant raw water intakes. You could just switch and
clean out the other at your leasure.
I have a duel primary fuel filter system, which allows a switch over. Just
takes a second to do it.
http://picasaweb.google.com/SailNOW....67273722420322
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"j" ganz @@
www.sailnow.com