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.