I tried to remove my thermostat today. The engine is pretty tight
under the deck so it's hard get at. I got the two bolts out but the
housing still felt like it was welded to the engine.

Is there a lip on the housing that could have rusted it in place or is
it just stuck by the gasket? I'd like a better idea how it goes
together before putting much force on it.

Symptoms of how the engine behaves when the thermostat fails would be
helpful. The engine (raw water version) seems to be running fine so
maybe I'll leave it. OTOH, judging from the paint, no one has had the
thermostat out since 1980.

--

Roger Long

Roger Long wrote:
I tried to remove my thermostat today. The engine is pretty tight
under the deck so it's hard get at. I got the two bolts out but the
housing still felt like it was welded to the engine.

Is there a lip on the housing that could have rusted it in place or is
it just stuck by the gasket? I'd like a better idea how it goes
together before putting much force on it.

Symptoms of how the engine behaves when the thermostat fails would be
helpful. The engine (raw water version) seems to be running fine so
maybe I'll leave it. OTOH, judging from the paint, no one has had the
thermostat out since 1980.

--

Roger Long

Roger,

A thermostat can fail in two ways, it never closes or it never opens.
Never closing results in an engine that always runs too cold, never
warms up. If the engine smoked a little until it warmed up in the past,
and now smokes all the time, it could be the thermostat (have a look at
the temp gauge if you have one). A thermostat that never opens causes
the engine to run too hot, the temp indicator will show this (if you
have one), but a bad water pump impeller would be the first thing I
would check.

Is their any possibility that their could be bolts that come in from
behind the thermostat housing that you didn't notice? I found this out
on my Cats when I tried to replace the thermostats on one engine. I
finally called the local distributer and asked for a field service
representitive, he knew all about the bolts in the back. You might try
calling the local distributer, they might know something usefull, it
can't hurt to try.

John

On Fri, 02 Jun 2006 01:14:49 GMT, "Roger Long"
wrote:

I tried to remove my thermostat today. The engine is pretty tight
under the deck so it's hard get at. I got the two bolts out but the
housing still felt like it was welded to the engine.

Is there a lip on the housing that could have rusted it in place or is
it just stuck by the gasket? I'd like a better idea how it goes
together before putting much force on it.

Symptoms of how the engine behaves when the thermostat fails would be
helpful. The engine (raw water version) seems to be running fine so
maybe I'll leave it. OTOH, judging from the paint, no one has had the
thermostat out since 1980.

Yanmar has great parts manuals that show an exploded view of probably
everything. It's about a 40 dollar investment that pays off very well.
I have a different model but on mine the two bolts are all that holds
it on.