On 2008-08-01 02:35:06 -0400, Stephen Trapani said:

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

By its output (15 hp), I believe yours is a raw water cooled engine.
Water temps must be lower or you'll suffer deposits that'll make life
less than primo over time.

Yanmar had a great rep before they switched to closed-loop fresh water
cooled engines that like higher temps. My experience of the later
version tells me that they know what they are doing -- no problems not
fuel related in 1500 or so hours. I'm not exactly OCD on that subject
as it's never failed us in 16 seasons of fairly heavy usage.

If people with direct experience respond, of course listen to them.

--
Jere Lull
Xan-à-Deux -- Tanzer 28 #4 out of Tolchester, MD
Xan's pages: http://web.mac.com/jerelull/iWeb/Xan/
Our BVI trips & tips: http://homepage.mac.com/jerelull/BVI/