Hi I have a 2002 19' bayliner with a merc 3.0L. The manual says that it
has a 160 degree thermostat in it but I warm up to 175 and stay there
from idle to WOT. Sometimes it creeps up to 179 but then goes back down
to 175.

Shouldn't i be running at 160 degrees with a 160 degree thermostat?

wrote in message
ps.com...
Hi I have a 2002 19' bayliner with a merc 3.0L. The manual says that it
has a 160 degree thermostat in it but I warm up to 175 and stay there
from idle to WOT. Sometimes it creeps up to 179 but then goes back down
to 175.

Shouldn't i be running at 160 degrees with a 160 degree thermostat?


Could be a bad temp guage, bad sender, bad thermostat. If running in fresh
water, do not worry about it. Runs better at a higher temperature. Most
RWC's are set up with the 160 stat so if you run in salt water, the salt
does not precipitate out.

wrote in message
ps.com...
Hi I have a 2002 19' bayliner with a merc 3.0L. The manual says that it
has a 160 degree thermostat in it but I warm up to 175 and stay there
from idle to WOT. Sometimes it creeps up to 179 but then goes back down
to 175.

Shouldn't i be running at 160 degrees with a 160 degree thermostat?


No. All it means is that the thermostat is supposed to be fully open at 160
degrees and starts closing below 160 degrees.

Your actual engine temperature above that will be determined by how
effective the rest of the cooling system is and water temperature.

Eisboch

If it had a stuck thermostat it would overheat.

Shortwave Sportfishing wrote:
On Mon, 18 Sep 2006 02:55:14 -0400, "Eisboch" wrote:


wrote in message
ups.com...
Hi I have a 2002 19' bayliner with a merc 3.0L. The manual says that it
has a 160 degree thermostat in it but I warm up to 175 and stay there
from idle to WOT. Sometimes it creeps up to 179 but then goes back down
to 175.

Shouldn't i be running at 160 degrees with a 160 degree thermostat?


No. All it means is that the thermostat is supposed to be fully open at 160
degrees and starts closing below 160 degrees.

Your actual engine temperature above that will be determined by how
effective the rest of the cooling system is and water temperature.

On the other hand, it could mean a stuck thermostat.

"jamesgangnc" wrote in message
oups.com...

If it had a stuck thermostat it would overheat.


That's what I figured, but then realized it could also be stuck open or
anywhere between full open or closed. Unlikely though.

My understanding of the purpose of the thermostat is to allow the engine to
warm up to normal operating temperature by preventing external water/coolant
from the manifolds, heat exchanger or radiator (in the case of an
automobile) from flowing in the block until it reaches the temperature
rating of the thermostat.

I don't think the thermostat "modulates" to maintain a specific temperature
.... but maybe I am wrong?

Eisboch

The effect of athermostat is to cause a more constant operating
temperature. But it's not going to be the temperature on the
thermostat. 175 is not too high if there are no other symptoms like
dieseling or detonation. If there are you can go to a 147 thermostat
from merc.

Eisboch wrote:
"jamesgangnc" wrote in message
oups.com...

If it had a stuck thermostat it would overheat.


That's what I figured, but then realized it could also be stuck open or
anywhere between full open or closed. Unlikely though.

My understanding of the purpose of the thermostat is to allow the engine to
warm up to normal operating temperature by preventing external water/coolant
from the manifolds, heat exchanger or radiator (in the case of an
automobile) from flowing in the block until it reaches the temperature
rating of the thermostat.

I don't think the thermostat "modulates" to maintain a specific temperature
... but maybe I am wrong?

Eisboch

"Eisboch" wrote in message
...

"jamesgangnc" wrote in message
oups.com...

If it had a stuck thermostat it would overheat.


That's what I figured, but then realized it could also be stuck open or
anywhere between full open or closed. Unlikely though.

My understanding of the purpose of the thermostat is to allow the engine
to warm up to normal operating temperature by preventing external
water/coolant from the manifolds, heat exchanger or radiator (in the case
of an automobile) from flowing in the block until it reaches the
temperature rating of the thermostat.

I don't think the thermostat "modulates" to maintain a specific
temperature ... but maybe I am wrong?

Eisboch


You are wrong. The stat will partially open, or close a littel when the
temp changes higher or lower.

Has it always ran at 175? If so it's normal. I have a Merc outboard which
has 142 thermostats which run around 140 in the spring and 165 later summer
when the water warms up.


wrote in message
ps.com...
Hi I have a 2002 19' bayliner with a merc 3.0L. The manual says that it
has a 160 degree thermostat in it but I warm up to 175 and stay there
from idle to WOT. Sometimes it creeps up to 179 but then goes back down
to 175.

Shouldn't i be running at 160 degrees with a 160 degree thermostat?

Well, I just purchased the boat in june and its always been 175. I
didn't think anything of it until I looked in the specifications and
saw that it has a 160 degree thermostat. I think i'm going to just
replace the thermostat with another 160 and see if that changes
anything. oh, i do get a little deiseling on occassion.

Troy

Lost In Space/Woodchuck wrote:
Has it always ran at 175? If so it's normal. I have a Merc outboard which
has 142 thermostats which run around 140 in the spring and 165 later summer
when the water warms up.


wrote in message
ps.com...
Hi I have a 2002 19' bayliner with a merc 3.0L. The manual says that it
has a 160 degree thermostat in it but I warm up to 175 and stay there
from idle to WOT. Sometimes it creeps up to 179 but then goes back down
to 175.

Shouldn't i be running at 160 degrees with a 160 degree thermostat?

Has the raw water pump impeller ever been replaced? If you generally
are a summer boater you can use the 147 deg thermostat instead.
Deiseling does suggest that it is getting too hot. If it diesels then
it could also be detonating and that is bad for the engine.

wrote:
Well, I just purchased the boat in june and its always been 175. I
didn't think anything of it until I looked in the specifications and
saw that it has a 160 degree thermostat. I think i'm going to just
replace the thermostat with another 160 and see if that changes
anything. oh, i do get a little deiseling on occassion.

Troy

Lost In Space/Woodchuck wrote:
Has it always ran at 175? If so it's normal. I have a Merc outboard which
has 142 thermostats which run around 140 in the spring and 165 later summer
when the water warms up.


wrote in message
ps.com...
Hi I have a 2002 19' bayliner with a merc 3.0L. The manual says that it
has a 160 degree thermostat in it but I warm up to 175 and stay there
from idle to WOT. Sometimes it creeps up to 179 but then goes back down
to 175.

Shouldn't i be running at 160 degrees with a 160 degree thermostat?