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?