On 19 Jan 2004 06:19:16 -0800, (jzlatar-genesis)
wrote:

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


If a plugged raw water intake or sea strainer is not present, the
problem might be that the dry impeller is not creating a sufficient
vacuum to draw water. I have used two approaches.

1) try revving the engine to about 3000 rpm that might draw water
through the system.

2) (This one requires greater care.) Disconnect the water intake from
the inlet to the heat exchanger. While the engine is running apply
some vacuum to the hose just was you would when siphoning. When (if)
the water starts flowing, place it back on the inlet and tighten the
hose clamp.

I have used both techniques on a 3GM.

Also check the cam inside the impeller chamber. It might be worn.


Jack

__________________________________________________
Jack Dale
Swiftsure Sailing Academy
Director/ISPA and CYA Instructor
http://www.swiftsuresailing.com
Phone: 1 (877) 470-SAIL (toll free)
__________________________________________________

On 19 Jan 2004 06:19:16 -0800, (jzlatar-genesis)
wrote:

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
The mixing elbow is a known weak point in small Yanmars. This is the
place the raw water enters the exhaust. It's supposed to be good for
about 500 hrs or 6-7 years, whichever comes first.

My experience was with a 3GM30F, but I believe that the 2GM20F is
quite similar. Find the raw water exit from the heat exchanger and
trace it to the exhaust pipe. On most boats, the mixing elbow is
shaped like an upside down "U", but it could be just a pipe slanting
downward away from the engine. Pull the water hose off of this
fitting to see if there is any flow at this point. If there is,
you've found the problem, or at least one problem. Don't try to rod
out the mixing elbow to get the water flowing again. Just replace it.
If you're going to try to replace it yourself, remove the entire
exhaust pipe from where it is bolted to the exhaust manifold at the
back of the heat exchanger. It's easier and safer than trying to work
on it in place. Don't forget that you'll need a new gasket. For the
"U" shaped mixing elbow, I seem to recall that there is an adapter
with a reverse thread that has to be removed. Good luck, and let us
know how it goes.

__________________________________________________ __________
Glen "Wiley" Wilson usenet1 SPAMNIX at worldwidewiley dot com
To reply, lose the capitals and do the obvious.

Take a look at cpRepeater, my NMEA data integrator, repeater, and
logger at http://www.worldwidewiley.com/

On 19 Jan 2004 06:19:16 -0800, (jzlatar-genesis)
wrote:

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
The mixing elbow is a known weak point in small Yanmars. This is the
place the raw water enters the exhaust. It's supposed to be good for
about 500 hrs or 6-7 years, whichever comes first.

My experience was with a 3GM30F, but I believe that the 2GM20F is
quite similar. Find the raw water exit from the heat exchanger and
trace it to the exhaust pipe. On most boats, the mixing elbow is
shaped like an upside down "U", but it could be just a pipe slanting
downward away from the engine. Pull the water hose off of this
fitting to see if there is any flow at this point. If there is,
you've found the problem, or at least one problem. Don't try to rod
out the mixing elbow to get the water flowing again. Just replace it.
If you're going to try to replace it yourself, remove the entire
exhaust pipe from where it is bolted to the exhaust manifold at the
back of the heat exchanger. It's easier and safer than trying to work
on it in place. Don't forget that you'll need a new gasket. For the
"U" shaped mixing elbow, I seem to recall that there is an adapter
with a reverse thread that has to be removed. Good luck, and let us
know how it goes.

__________________________________________________ __________
Glen "Wiley" Wilson usenet1 SPAMNIX at worldwidewiley dot com
To reply, lose the capitals and do the obvious.

Take a look at cpRepeater, my NMEA data integrator, repeater, and
logger at http://www.worldwidewiley.com/

On 19 Jan 2004 06:19:16 -0800, (jzlatar-genesis)
wrote:

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

When you open up the pump and open the seacock, does seawater come
out? Maybe it isn't priming!

I tried this with a neighbor's overheating problem. No water to the
pump. Diver didn't find anything on the outside, but he plugged the
hole and we found half a plastic ice bag inside the seacock some idiot
threw overboard somewhere. Sure plugged up the works. The strainer
looked fine. It had water in it but no flow. We also re-routed a
hose I thought came up above the water line that might prevent the
pump from priming. We had plenty of water, after both....got both
bilge pumps running...(c;



Larry W4CSC

On 19 Jan 2004 06:19:16 -0800, (jzlatar-genesis)
wrote:

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

When you open up the pump and open the seacock, does seawater come
out? Maybe it isn't priming!

I tried this with a neighbor's overheating problem. No water to the
pump. Diver didn't find anything on the outside, but he plugged the
hole and we found half a plastic ice bag inside the seacock some idiot
threw overboard somewhere. Sure plugged up the works. The strainer
looked fine. It had water in it but no flow. We also re-routed a
hose I thought came up above the water line that might prevent the
pump from priming. We had plenty of water, after both....got both
bilge pumps running...(c;



Larry W4CSC

"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

"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

In article ,
jzlatar-genesis wrote:

Regarding the muffler, I presume that is working because the fumes
come out,
NO NO NO NO NO NO ..... fumes AND water need to come out of the exhaust
system. If you have water up to the engine as per your prior
inspection, then open/disconnect the water exit hose of the exhaust
manifold; if flow then you probably have a 'salted' injection elbow, if
no flow then you probably have a fouled exhaust manifold. Cast irion
exhaust manifolds can fail in two ways: corrosion of the base metal
that issues huge platelettes' of rust that lodge in and block the flow
channels ..... or the deposition of carbonate salts (boiler scale
fouling).

What engine do you have?



if the heat exchanger,is clogged, that means that I have to
open the engine?

In article ,
jzlatar-genesis wrote:

Regarding the muffler, I presume that is working because the fumes
come out,
NO NO NO NO NO NO ..... fumes AND water need to come out of the exhaust
system. If you have water up to the engine as per your prior
inspection, then open/disconnect the water exit hose of the exhaust
manifold; if flow then you probably have a 'salted' injection elbow, if
no flow then you probably have a fouled exhaust manifold. Cast irion
exhaust manifolds can fail in two ways: corrosion of the base metal
that issues huge platelettes' of rust that lodge in and block the flow
channels ..... or the deposition of carbonate salts (boiler scale
fouling).

What engine do you have?



if the heat exchanger,is clogged, that means that I have to
open the engine?

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