On Thu, 31 Jul 2008 23:35:06 -0700, Stephen Trapani
wrote:

A while back I had a guy put a temperature gauge on my Yanmar. I thought
he installed it incorrectly until last weekend. A guy loaned me this
slick hand held temperature laser gauge thing which he said to aim at
the thermostat body for the running temperature of the motor. It read
115. The installed gauge starts at 120. Once I shut off the motor I
switched the key back on and it read about 135 on the installed gauge.
Must have warmed up once the water wasn't running through it. So the
installed gauge works, but the motor pretty much never gets up to 120.
And I mean never, when it's running, even when I have it full throttle,
pushing the boat along for hours!

So my question is this: A nearby very experienced boat refurbisher guy
with alot of Yanmar experience said I should decrease the flow in the
raw water sea cock until the temp reads 140-160. He said some diesel
motors use this method (Perkins I think he said). He said I shouldn't
mess with the thermostat because it was easier to just decrease the
water flow through the sea cock. This won't hurt the water pump? I
asked. No, he said.

So, good idea? Is it a big deal to keep the motor running warmer? Bad
idea to decrease the flow through the ball valve sea cock? What do you
all think?

Stephen

Your 2QM15 should have a thermostat, part number 124770-49200 (Raw
water cooled engine) and a 46150-004531 over temp sender. Operating
temperature should be in somewhere around the 140 - 160 deg. F. range
but the idea of closing the water inlet to control temperature is not
something that is usually done. Certainly I've owned and worked on
Perkins engines for years and this scheme was never recommended by the
factory or any installer I ever came in contact with.

Just go out and buy a thermostat and install it, it is right there on
the front of the engine and easy to get to.

I'm not 100% sure, but I believe that the over temp warning sender on
a raw water cooled engine is set to 180 deg. F. But you should check
this figure as it has been some time since I worked on a 2 cyl.
Yanmar.


Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)