This is not a closed cooling system just a standard cooling system
where the boat draws sal****er from the ocean. The manual says that
the thermostat should start opening at a temp of 160F and be fully
opened at around 180F.

I plan to remove the thermostat housing (and the new thermostat) and
reassemble the housing without a thermostat in it. This should allow
me to determine if the problem is the thermostat or not. Without a
thermostat, I am assuming that cooling water is drawn all the time so
in therory, the boat should not overheat. If it does, it probably
means that the problem is elsewhere (plugged hose, riser, water pump,
impeller, etc..)

A.

On 17 Aug 2005 21:26:53 -0700, wrote:


Melandre wrote:
I am suspecting my boat's (1990 Ford OMC Cobra 2.3L) overheating
problem comes from a defective thermostat. Today, I replaced the
thermostat but the gasket that I was given does not fit the housing at
all so I had to reuse the old worn gasket for now. I started the
boat and it gradually went to over 200 degrees which means the problem
is not fixed. I also noticed that steam was coming out of the
thermostat housing around the old gasket. So obviously I don't have a
100% seal and I will need to find the proper gasket.

However, I am wondering if the leaking gasket would be enough to
cause the new thermostat not to work or if I simply misdiagnosed the
problem in the first place and will have to look somewhere else?

Impeller and water pump was replaced 2 months ago so I don't think
this is the cause. Will have to also check the hoses and the water
intake I suppose.

Andre

It may be OK for a pressurized cooling system to run at 200 degrees.
What does your OM say? However, if you have steam leaking out from
around the thermostat gasket you don't have proper pressurization and
that will lower the boiling point of your coolant substantially.