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On 16 May 2004 19:39:26 -0700, (Eldon Cutlip)
wrote:

Well, I replaced the thermostat in the cold motor. And I tried to find
"heat sticks" and nobody in the 3 auto part stores I went to knew what
they were. They did sell some laser things starting at about $100. But
I couldn't justify that for a one time deal. After replacing the
thermostat in the cold motor, it went up to about mid-way in the red
at idle. And my wife and I put our hands on the thermostat housing
after letting it idle in the red for about 5 minutes or so and counted
to between 3 and 4 seconds until we had to pull our hands off it. I
ran the "hot" motor and it ended up just slightly higher than mid-way
in the red and we could put our hands on the thermostat housing for
between 4 and 5 seconds. So, I was figuring that the guages just
weren't the right ones for this engine and that the engines were
running fine.

I then took them out on the water and both of them were idling in the
red (about mid-way). I then opened them up to about 2000 or so rpms
and they both cooled down to about mid-green. Then I think let them
idle again and the "hot" engine got to the top of the red again. So, I
shut that one off and ran the "cool" engine for a few minutes around
4000 rpms and I looked down and saw that one was up in the red. That
kind of surprised me because I had been thinking that at least the
"cold" motor would run well. The other day we had run that one for a
good 20 minutes at the same speed and it stayed in the green (that was
before we put the new thermostat in). Then we decided to head back -
and I kind of took turns with the motors trying to keep them as cool
as I could. Just before we got back we heard what I suspect was an
overheat alarm beep. So I shut them both off and tried to get anchored
- but we were in the way in the harbor by that time. When I turned the
key back on for the cold motor we just heard a steady alarm. So I
turned the key back on the for hot motor and puttered over - but it
was running "rough" by then I would say - it shut off once by itself -
and it didn't start right up that time.

So, I was thinking I must need have a semi-bad impeller in both motors
at this point. So, I just took apart the lower unit and pulled the
water pump on the cold motor. The impeller looked fine - no wear or
tear and still quite bendy. The inside of the water pump lining
doesn't have any scratches. So now I'm totally out of ideas. At this
point I'm believing the guages - since the overheat alarm sounded. Is
it possible I replaced the old thermostat that was stuck wide open in
the cold motor with a thermostat rated for a different temperature?
The new one looked the same as the old one (wierd plastic things -
kind of look like some kind of practice tips for archery (but too big
and plastic) with threads on the "shank" side that don't seem to
thread into anything). But I did notice the old one has 10LT stamped
on it and the new ones I got have G1C stamped on them.

Any ideas are GREATLY appreciated! Eldon

Here's what I would do .....

Remove both themostats and plonk them in a pot on the stove and fill
it with water. Gently bring to the boil, or thereabouts, and check
that they both open at the same time (note the temperature). Allow to
cool and check the same for closing.
The fact that there's a thread on the one end that doesn't screw into
anything ...... is a big red flag to me!

I glanced through my Johnson Manual for tips. They mention that if a
thermostat sticks, it's usually in the "open" position?????. They have
a picture of a motor running (BRIEFLY) without the thermostat &
housing, to check the water flow. They also suggest grounding out the
temp. sensor to check the buzzer and gauges. CAUTION. If you do any of
this, do so at your own risk, don't hold me liable.

As an aside, I have a mechanical temp. gauge on my car, so it's always
"on". I've noticed that when I switch the engine off, after a minute
or two, it climbs pretty high. The engine heat is transferred to the
water but because the water is not circulating, it gets nice and hot.
Is it possible this is what happened to set your alarm off?

You might consider dropping $100 for a infra red themometer. I have
one and they are very handy, especially for checking tire and bearing
temperatures while towing, and poor house insulation in Winter etc..
Because you have 2 motors, you can do quick comparisons at various
points.

Also, I think it's imperative that you verify that both your sender
units and gauges are accurate. There are ways to do this but I'm
nervous about giving unqualified advice.

Good Luck.

PS. As a matter of course, you should change both impellors,
especially if you don't know their history.