I have an old Yanmar 2QM15 - It has a temperature alarm, but no gauge.

What would be the best way to add a gauge? Is there a replacement sender
that would screw into same port as existing temperature switch and act as
both temperature switch and input for analogue gauge?

Or is there another way to add a block water temperature measurement?

My engine seems to be running too cold. I am planning on pulling the
thermostat and checking it's setting. If it is set too low, is there a
source for units with higher settings? We are in fresh water, so would like
to have engine run hotter - say 160F or so.

The part number for the OEM thermostat is 124770-49200 but I have not been
able to find out the temperature - I have read that it may be 120F or 140F
but that's just on web discussions.

Don't know what the setting of the existing temperature switch is either.
Anyone know?

On Mon, 14 Aug 2006 21:43:30 -0400, "OldSailor"
wrote:

I have an old Yanmar 2QM15 - It has a temperature alarm, but no gauge.

What would be the best way to add a gauge? Is there a replacement sender
that would screw into same port as existing temperature switch and act as
both temperature switch and input for analogue gauge?

Or is there another way to add a block water temperature measurement?

My engine seems to be running too cold. I am planning on pulling the
thermostat and checking it's setting. If it is set too low, is there a
source for units with higher settings? We are in fresh water, so would like
to have engine run hotter - say 160F or so.

The part number for the OEM thermostat is 124770-49200 but I have not been
able to find out the temperature - I have read that it may be 120F or 140F
but that's just on web discussions.

Don't know what the setting of the existing temperature switch is either.
Anyone know?

I got a most excellent service manual and parts manual for my 4JH2
engine. It answers those questions (for my engine). Worth the
investment....

OldSailor wrote:
I have an old Yanmar 2QM15 - It has a temperature alarm, but no gauge.

Great!

I got a QM30H.

We are in fresh water, so would like
to have engine run hotter - say 160F or so.


Hi:

First questoin ya gotta be able to answere is..........

Fresh water + Coolant in cooling system (like your car)?
or
raw water cooled (engine stays cool by using the liquid that supports
your boat.)?

Then ya got the Sea v. Lake/River (fresh) water choice.

I have read that it may be 120F or 140F
but that's just on web discussions.

Get the book by SELOC titled "Yanmar Diesels 1975-1985" (or someplace
around those dates. Cheep, fast to get, and good enough.

Depending on how your motor is cooled will detrmine the SAFE operating
tempratures.
Bob

OldSailor wrote:
I have an old Yanmar 2QM15 - It has a temperature alarm, but no gauge.

What would be the best way to add a gauge? Is there a replacement sender
that would screw into same port as existing temperature switch and act as
both temperature switch and input for analogue gauge?

I have a pair of 2GM20's on my cat. I added two water temp guages
purchased from West Marine - they're pretty generic. The block has
several places that you can add a sensor. For instance, there should
be taps for sending the coolant to a hot water heater. You can also
simply add a tee with the alarm.

Or is there another way to add a block water temperature measurement?

My engine seems to be running too cold. I am planning on pulling the
thermostat and checking it's setting. If it is set too low, is there a
source for units with higher settings? We are in fresh water, so would like
to have engine run hotter - say 160F or so.

One of my engines runs at 165 to 175, depending on the load from the
big alternator and the heater. The other, without these loads, runs
at 160-165, depending on how hard I push.

I normally run at 2800-3000 RPM. If I back off to 2400, then the
temps will stay at 160. Also, in the Spring or in Maine, where the
water is 55 degrees, the engines will stay pretty cool.

BTW, one season I had the opposite problem - both engines ran hot,
running up to 190 or more if I tried to go over 2600 RPM. Finally I
stripped down both heat exchangers and found eel grass. Although the
flow looked good from the outside, it was insufficient.


The part number for the OEM thermostat is 124770-49200 but I have not been
able to find out the temperature - I have read that it may be 120F or 140F
but that's just on web discussions.

Don't know what the setting of the existing temperature switch is either.
Anyone know?

I thought the fresh water thermostat was set at 175, but my books are
all on the boat.

Also, I second the advice to get the Seloc book. Also you should have
the shop manual and the parts books.

"Jeff" wrote

I have a pair of 2GM20's on my cat. I added two water temp guages
purchased from West Marine - they're pretty generic. The block has
several places that you can add a sensor. For instance, there should
be taps for sending the coolant to a hot water heater.

The 2QM15 is a raw water cooled engine so no water heater taps, but there
are a few other plugs. Problem may be getting them out without damage after
almost 30 yrs?

You can also simply add a tee with the alarm.

If alarm is in a dead end rather than in water flow, I am a bit concerned it
may not see actual temperature and may collect scale, but worth looking at.
There is a place where block water exits head before going to manifold via
rubber hose - I could put gauge sensor there, but it would be neater if I
could use one sensor for gauge and alarm.

One of my engines runs at 165 to 175, depending on the load from the
big alternator and the heater. The other, without these loads, runs
at 160-165, depending on how hard I push.


I thought the fresh water thermostat was set at 175, but my books are
all on the boat.

Presumably you have closed circuit fresh water cooling - We are once
through. But, because we are IN fresh lake water, scaling should not be a
problem and I hope to get temperatures up to those that you see. To do
this, I will need a new thermostat and possibly temperature switch. Yanmar
don't seem to have these specific parts listed for my engine, but perhaps
parts from other engines may fit?


Also, I second the advice to get the Seloc book. Also you should have
the shop manual and the parts books.

I already have the owners manual and illustrated parts book - I ordered the
Seloc manual about a week ago without ever having seen one - Glad to hear it
might be useful. Some of those generic manuals are not that great! Shop
manual may be worthwhile, especially if I ever decide to rebuild engine
myself.

Sorry - I misread your "fresh water" comment as meaning this was a
"fresh water version" of the engine, which I believe Yanmar did make.

I've heard the that the raw water versions have the thermostat set at
either 125 or 140 degrees, but I don't know for sure which is right or
whether there's a good alternative. You could call Torresen, who
certainly has experience running Yanmars in fresh water.

OldSailor wrote:
"Jeff" wrote
I have a pair of 2GM20's on my cat. I added two water temp guages
purchased from West Marine - they're pretty generic. The block has
several places that you can add a sensor. For instance, there should
be taps for sending the coolant to a hot water heater.

The 2QM15 is a raw water cooled engine so no water heater taps, but there
are a few other plugs. Problem may be getting them out without damage after
almost 30 yrs?

You can also simply add a tee with the alarm.

If alarm is in a dead end rather than in water flow, I am a bit concerned it
may not see actual temperature and may collect scale, but worth looking at.
There is a place where block water exits head before going to manifold via
rubber hose - I could put gauge sensor there, but it would be neater if I
could use one sensor for gauge and alarm.

One of my engines runs at 165 to 175, depending on the load from the
big alternator and the heater. The other, without these loads, runs
at 160-165, depending on how hard I push.

I thought the fresh water thermostat was set at 175, but my books are
all on the boat.

Presumably you have closed circuit fresh water cooling - We are once
through. But, because we are IN fresh lake water, scaling should not be a
problem and I hope to get temperatures up to those that you see. To do
this, I will need a new thermostat and possibly temperature switch. Yanmar
don't seem to have these specific parts listed for my engine, but perhaps
parts from other engines may fit?

Also, I second the advice to get the Seloc book. Also you should have
the shop manual and the parts books.

I already have the owners manual and illustrated parts book - I ordered the
Seloc manual about a week ago without ever having seen one - Glad to hear it
might be useful. Some of those generic manuals are not that great! Shop
manual may be worthwhile, especially if I ever decide to rebuild engine
myself.

A fresh water cooled (with heat exchanger) engine should have a 180
degree thermostat. You will get better combustion efficiency, etc.

A raw water cooled (no matter if lake or sea water) should have a 135
degree thermostat. The dissolved carbonates in raw water will begin to
precipitate and foul the engine when raw water goes over about 143
deg. F. Lake water has less dissolved carbonates, so it just 'takes
longer' to foul. Of course you can run with either T'stat but will
have to 'pickle' (muriatic acid or commercial boiler descaleing
compound) the engine internals if running in raw water more often with
the 180 T'stat. ;-)



In article , OldSailor
wrote:

I have an old Yanmar 2QM15 - It has a temperature alarm, but no gauge.

What would be the best way to add a gauge? Is there a replacement sender
that would screw into same port as existing temperature switch and act as
both temperature switch and input for analogue gauge?

Or is there another way to add a block water temperature measurement?

My engine seems to be running too cold. I am planning on pulling the
thermostat and checking it's setting. If it is set too low, is there a
source for units with higher settings? We are in fresh water, so would like
to have engine run hotter - say 160F or so.

The part number for the OEM thermostat is 124770-49200 but I have not been
able to find out the temperature - I have read that it may be 120F or 140F
but that's just on web discussions.

Don't know what the setting of the existing temperature switch is either.
Anyone know?

"Rich Hampel" wrote

A fresh water cooled (with heat exchanger) engine should have a 180
degree thermostat. You will get better combustion efficiency, etc.

No heat exchanger on this engine.


A raw water cooled (no matter if lake or sea water) should have a 135
degree thermostat. The dissolved carbonates in raw water will begin to
precipitate and foul the engine when raw water goes over about 143
deg. F.

I do recall this from heat exchanger design - We used to limit cooling water
exit temperature to 55C which is about 131F. But this was for 24/7
operation. Sailboat engine runs for so few hours, that this could perhaps be
increased a bit.

I would like to get temperature up a bit but don't know which thermostat to
order that would fit the 2QM15 .