On Sat, 10 Dec 2005 09:33:29 +1000, LD wrote:

You should be able to remove the sensor and with the ignition on place
it in "warm" water. Maybe it's defective. LD

"brianM" wrote in message
news
I know this is an old chesnut and has been well thrashed out in this
group, but I have group googled about this ongoing problem and none of
the answers quite fit. I had the outboard serviced recently by the
Johnson agent in my area, the thermostat was replaced and everything
else checked out, however the motor will only run at full throttle for
2 mins before the overheat alarm comes on. I use a 50-1 2-stroke oil
fuel mix. Once throttled back to idle, alarm goes off in 2-4 mins.
After
that
I can plane at about 2/3 throttle indefinitely The water pump indicator
at the top of the motor has a steady stream out of the hose at all
times and after the OMC warning goes off, the water stream is hardly
warm let alone hot.
I have checked for debris clogging the intakes etc. Motor is flushed
out with fresh water after EVERY trip. Spark plugs are correct model
and new. I don't think the motor is overheating at all, but I play
safe
anyway.
Before I go back to the agent, can I get some suggestions as to what
might
be
the problem. Details of the rig:
1989 30hp Johnson electric start 2-stroke, runs only in salt water on a
4metre aluminum runabout. I use only Johnson oil products. thanks
Brian M

I will look at that too - thanks
BrianM