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.

"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.

--
"j" ganz @@
www.sailnow.com

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.

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
[at]=@, [dash]=- & [dot]=. *Warning* HTML & 32K emails -- NUL:

"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


--
"j" ganz @@
www.sailnow.com

On Oct 29, 3:12*pm, "Capt. JG" wrote:
"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....0#533996727372...

--
"j" ganz

The water intake has slits parallel to the keel so a piece of shell
could have slipped in. I go aground a lot on oyster bars because I
like to go where I am not supposed to go in my boat and I assume this
is how it got there. The seacock actually was a ball valve which is
why I could not see the piece of shell trapped below it. I actually
reamed the ball valve with a piece of Stainless stock and went under
the boat with a Sawzall blade to clear the slits on the intake.
Nothign helped untill I unscrewed the ball valve and capped the open
intake with a wood plug and then looked in the valve, Voila!
It is even worse than this because I had my boat hauled to paint it
AND to clear the slotted intake and found nothing while she was out of
the water.

On Oct 30, 1:22*pm, Frogwatch wrote:
On Oct 29, 3:12*pm, "Capt. JG" wrote:



"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....0#533996727372...

--
"j" ganz

The water intake has slits parallel to the keel so a piece of shell
could have slipped in. *I go aground a lot on oyster bars because I
like to go where I am not supposed to go in my boat and I assume this
is how it got there. *The seacock actually was a ball valve which is
why I could not see the piece of shell trapped below it. *I actually
reamed the ball valve with a piece of Stainless stock and went under
the boat with a Sawzall blade to clear the slits on the intake.
Nothign helped untill I unscrewed the ball valve and capped the open
intake with a wood plug and then looked in the valve, Voila!
It is even worse than this because I had my boat hauled to paint it
AND to clear the slotted intake and found nothing while she was out of
the water.

I had a friend on a 41' Gulfstar whose sal****er pump stopped and he
kept her running by rigging a funnel to a piece of hose to the cockpit
and then pulling up a bucket of water every 3 minutes and pouring it
into the funnel and using gravity to feed it. It beat waiting for the
wind for him to get her into port.

On Thu, 29 Oct 2009 10:19:42 -0700, "Capt. JG"
wrote:

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.

Put a tire valve on the thru hull. Carry a tank and a small, cheap 12V
air compressor, things nice to have for any trailer rig. If you have a
boat too big to trailer, you can tap off the air for the horn.

Casady