I've never opened the heat exchanger on my Yanmar - I've done it on a Westerbeke
without too much hassle. You should be able to remove the end caps while its on
the engine. However, pull the hose that feeds the elbow and repeat the flow
test. This will tell you where the problem is. Its a bit of a pain because
the elbow fitting has a little ridge on it - this might be a good time to add a
"hose pick" to the tool box. Its like a screwdriver with a bent point for a
tip - you work it around to loosen the hose.

On other thing to invest in is a parts book. This includes blowup diagrams of
everything so you can see what you're up against. Torrenson is a good source,
as is Mack Boring or Mastry in the USA.

-jeff




"jzlatar-genesis" wrote in message
m...
"Jeff Morris" wrote in message
...
You should be able to verify the intake end, including the pump, simply by
disconnecting the pump output and turning the engine over for a few seconds
with
the compression releases open. It should pump a good stream immediately. I
assume you have done that from your comment of "pump is working."

The next step is the heat exchanger, which can be clogged, and following
that is
the exhaust elbow. If you have flow from the pump, you can disconnect the
line
from the heat exchanger to the elbow and turn it over again.

One of my engines carbons up the elbow so quickly enough that I pull it and
scrape it out every year or two. Its only a 1 hour job if you have the
gaskets
and the wrenches that can reach the nuts. Its also possible that the exhaust
pipe or muffler has a problem, but the engine wouldn't start if the exhaust
was
actually clogged.

-jeff



"Leanne" wrote in message
...

"Ray D" rayd at gis.net wrote in message
...
Clogged raw water intake?

I would also check the raw water strainer and when the impeller
was changed, was it whole or was there a piece missing that could
have moved into the cooling system.

Leanne

"jzlatar-genesis" wrote in message
om...
I have a yanmar 2GM20F installed in a Plenamar 300 with the
following
problem, No water coming out of the exhaust pipe with the
result of
overheating and the pump is working with a new impeller, what
could be
the reason for it and the solution.
Thanks in advance
Jzlatar-geminis

Thanks for the prompt response.
yes I disconnect the pump output and turn the engine over for a few
seconds with
the compression releases open. I have a good stream immediately, for that
reason know that the pump is working, when I change the impeller the old one was
intact.
Regarding the muffler, I presume that is working because the fumes
come out, if the heat exchanger,is clogged, that means that I have to
open the engine?

Jorge