I recently purchased a boat that has 2 1986 Johnson 70 motors on it.
On the first run out we noticed that the temperature guage for one of
them went up to the top of the red while the other stayed in the
bottom 1/3rd of the green. We stopped the motors and took the covers
off and put our hands on both of the heads near the spark plugs. The
one that had stayed in the green was barely warm and the one that was
in the red was hot enough to bother your hand if you left it resting
on it for 30 seconds. We had actually never gone more than about 1/3rd
throttle on either engine for no more than about 5 minutes. And the
one in the red had only been at idle except for about 30 seconds when
I had put it up to about 1/3rd throttle. The pee stream on both motors
looked good. But on the one that was in the red, the pee stream was
even stronger - actually stronger than I have ever seen on outboards.
I replaced the thermostat because I was thinking that the impeller was
good because the pee stream was so good. But it still climbs up to the
red after just a few minutes at idle - and then the powerhead feels
hot to the touch - not like it burns your hand - but again
uncomfortable if you leave your hand on it for a while. Any ideas what
the next step should be? I called the local boat guys and they are all
at least 2 weeks out and halibut season opens Thursday - so I would
like to get a chance to use the boat before 2 weeks from now.


Thanks,
Eldon

Eldon Cutlip wrote:
I recently purchased a boat that has 2 1986 Johnson 70 motors on it.
On the first run out we noticed that the temperature guage for one of
them went up to the top of the red while the other stayed in the
bottom 1/3rd of the green. We stopped the motors and took the covers
off and put our hands on both of the heads near the spark plugs. The
one that had stayed in the green was barely warm and the one that was
in the red was hot enough to bother your hand if you left it resting
on it for 30 seconds. We had actually never gone more than about 1/3rd
throttle on either engine for no more than about 5 minutes. And the
one in the red had only been at idle except for about 30 seconds when
I had put it up to about 1/3rd throttle. The pee stream on both motors
looked good. But on the one that was in the red, the pee stream was
even stronger - actually stronger than I have ever seen on outboards.
I replaced the thermostat because I was thinking that the impeller was
good because the pee stream was so good. But it still climbs up to the
red after just a few minutes at idle - and then the powerhead feels
hot to the touch - not like it burns your hand - but again
uncomfortable if you leave your hand on it for a while. Any ideas what
the next step should be? I called the local boat guys and they are all
at least 2 weeks out and halibut season opens Thursday - so I would
like to get a chance to use the boat before 2 weeks from now.


Thanks,
Eldon

If you can hold your hand on it for 30 seconds, it's actually running
cold. It sounds like the gauge is inaccurate. There was no factory
provision for sending units on these engines except for the warning horn
switch, so the installation is suspect, too.

A count to about -6- before it gets too hot for your hand on the
thermostat housing is normal operating temperature. Maybe the pee
stream on the colder engine is weak because the thermostat is stuck open
or someone has removed it.

Rob

If I remove the thermostat from the one that is running hot (or at
least hotter), should that then duplicate the cold one - with the hand
test? And if so, that should prove the guage is the culprit?

Thanks,
Eldon

trainfan1 wrote in message ...
Eldon Cutlip wrote:
I recently purchased a boat that has 2 1986 Johnson 70 motors on it.
On the first run out we noticed that the temperature guage for one of
them went up to the top of the red while the other stayed in the
bottom 1/3rd of the green. We stopped the motors and took the covers
off and put our hands on both of the heads near the spark plugs. The
one that had stayed in the green was barely warm and the one that was
in the red was hot enough to bother your hand if you left it resting
on it for 30 seconds. We had actually never gone more than about 1/3rd
throttle on either engine for no more than about 5 minutes. And the
one in the red had only been at idle except for about 30 seconds when
I had put it up to about 1/3rd throttle. The pee stream on both motors
looked good. But on the one that was in the red, the pee stream was
even stronger - actually stronger than I have ever seen on outboards.
I replaced the thermostat because I was thinking that the impeller was
good because the pee stream was so good. But it still climbs up to the
red after just a few minutes at idle - and then the powerhead feels
hot to the touch - not like it burns your hand - but again
uncomfortable if you leave your hand on it for a while. Any ideas what
the next step should be? I called the local boat guys and they are all
at least 2 weeks out and halibut season opens Thursday - so I would
like to get a chance to use the boat before 2 weeks from now.


Thanks,
Eldon

If you can hold your hand on it for 30 seconds, it's actually running
cold. It sounds like the gauge is inaccurate. There was no factory
provision for sending units on these engines except for the warning horn
switch, so the installation is suspect, too.

A count to about -6- before it gets too hot for your hand on the
thermostat housing is normal operating temperature. Maybe the pee
stream on the colder engine is weak because the thermostat is stuck open
or someone has removed it.

Rob

I took the thermostat out of the "hot" one and then ran it on the
"ears." The engine stayed dead cold for as long as I ran it (probably
a few minutes). But the pee hole just dribbled a drop or so every few
seconds - no stream. Then I put the thermostat back in and it had a
good stream at the pee hole but the engine started heating up again.
Should I still get a good stream even with the thermostat out - if the
water pump is good? I know the powerhead was getting water because it
stayed dead cold and I saw water when I pulled the thermostat cover.

Thanks,
Eldon

trainfan1 wrote in message ...
Eldon Cutlip wrote:
I recently purchased a boat that has 2 1986 Johnson 70 motors on it.
On the first run out we noticed that the temperature guage for one of
them went up to the top of the red while the other stayed in the
bottom 1/3rd of the green. We stopped the motors and took the covers
off and put our hands on both of the heads near the spark plugs. The
one that had stayed in the green was barely warm and the one that was
in the red was hot enough to bother your hand if you left it resting
on it for 30 seconds. We had actually never gone more than about 1/3rd
throttle on either engine for no more than about 5 minutes. And the
one in the red had only been at idle except for about 30 seconds when
I had put it up to about 1/3rd throttle. The pee stream on both motors
looked good. But on the one that was in the red, the pee stream was
even stronger - actually stronger than I have ever seen on outboards.
I replaced the thermostat because I was thinking that the impeller was
good because the pee stream was so good. But it still climbs up to the
red after just a few minutes at idle - and then the powerhead feels
hot to the touch - not like it burns your hand - but again
uncomfortable if you leave your hand on it for a while. Any ideas what
the next step should be? I called the local boat guys and they are all
at least 2 weeks out and halibut season opens Thursday - so I would
like to get a chance to use the boat before 2 weeks from now.


Thanks,
Eldon

If you can hold your hand on it for 30 seconds, it's actually running
cold. It sounds like the gauge is inaccurate. There was no factory
provision for sending units on these engines except for the warning horn
switch, so the installation is suspect, too.

A count to about -6- before it gets too hot for your hand on the
thermostat housing is normal operating temperature. Maybe the pee
stream on the colder engine is weak because the thermostat is stuck open
or someone has removed it.

Rob

Eldon Cutlip wrote:

I took the thermostat out of the "hot" one and then ran it on the
"ears." The engine stayed dead cold for as long as I ran it (probably
a few minutes). But the pee hole just dribbled a drop or so every few
seconds - no stream. Then I put the thermostat back in and it had a
good stream at the pee hole but the engine started heating up again.
Should I still get a good stream even with the thermostat out - if the
water pump is good? I know the powerhead was getting water because it
stayed dead cold and I saw water when I pulled the thermostat cover.

Thanks,
Eldon

trainfan1 wrote in message ...

Eldon Cutlip wrote:

I recently purchased a boat that has 2 1986 Johnson 70 motors on it.
On the first run out we noticed that the temperature guage for one of
them went up to the top of the red while the other stayed in the
bottom 1/3rd of the green. We stopped the motors and took the covers
off and put our hands on both of the heads near the spark plugs. The
one that had stayed in the green was barely warm and the one that was
in the red was hot enough to bother your hand if you left it resting
on it for 30 seconds. We had actually never gone more than about 1/3rd
throttle on either engine for no more than about 5 minutes. And the
one in the red had only been at idle except for about 30 seconds when
I had put it up to about 1/3rd throttle. The pee stream on both motors
looked good. But on the one that was in the red, the pee stream was
even stronger - actually stronger than I have ever seen on outboards.
I replaced the thermostat because I was thinking that the impeller was
good because the pee stream was so good. But it still climbs up to the
red after just a few minutes at idle - and then the powerhead feels
hot to the touch - not like it burns your hand - but again
uncomfortable if you leave your hand on it for a while. Any ideas what
the next step should be? I called the local boat guys and they are all
at least 2 weeks out and halibut season opens Thursday - so I would
like to get a chance to use the boat before 2 weeks from now.


Thanks,
Eldon

If you can hold your hand on it for 30 seconds, it's actually running
cold. It sounds like the gauge is inaccurate. There was no factory
provision for sending units on these engines except for the warning horn
switch, so the installation is suspect, too.

A count to about -6- before it gets too hot for your hand on the
thermostat housing is normal operating temperature. Maybe the pee
stream on the colder engine is weak because the thermostat is stuck open
or someone has removed it.

Rob

With the thermostat out the pressure will fall off. Hence my suspicion
of your "cold" motor. The thermostats should be closed, or
substantially so, until around 150 degrees, and then they will let 150
degree or warmer water by. You can test them on your kitchen stove with
a candy thermometer if you must.

Where are your sending units?

Rob

If you want to eliminate the gauges, disconnect both sending units and
temporarily run a wire from the cool motor to the one showing hot and one
from the hot motor to the one running cool. If the problem now shows on the
one that was running cool, you know you have a bad gauge.

--
Bill
Chesapeake, Va


"Eldon Cutlip" wrote in message
m...
If I remove the thermostat from the one that is running hot (or at
least hotter), should that then duplicate the cold one - with the hand
test? And if so, that should prove the guage is the culprit?

Thanks,
Eldon

trainfan1 wrote in message
...
Eldon Cutlip wrote:
I recently purchased a boat that has 2 1986 Johnson 70 motors on it.
On the first run out we noticed that the temperature guage for one of
them went up to the top of the red while the other stayed in the
bottom 1/3rd of the green. We stopped the motors and took the covers
off and put our hands on both of the heads near the spark plugs. The
one that had stayed in the green was barely warm and the one that was
in the red was hot enough to bother your hand if you left it resting
on it for 30 seconds. We had actually never gone more than about 1/3rd
throttle on either engine for no more than about 5 minutes. And the
one in the red had only been at idle except for about 30 seconds when
I had put it up to about 1/3rd throttle. The pee stream on both motors
looked good. But on the one that was in the red, the pee stream was
even stronger - actually stronger than I have ever seen on outboards.
I replaced the thermostat because I was thinking that the impeller was
good because the pee stream was so good. But it still climbs up to the
red after just a few minutes at idle - and then the powerhead feels
hot to the touch - not like it burns your hand - but again
uncomfortable if you leave your hand on it for a while. Any ideas what
the next step should be? I called the local boat guys and they are all
at least 2 weeks out and halibut season opens Thursday - so I would
like to get a chance to use the boat before 2 weeks from now.


Thanks,
Eldon

If you can hold your hand on it for 30 seconds, it's actually running
cold. It sounds like the gauge is inaccurate. There was no factory
provision for sending units on these engines except for the warning horn
switch, so the installation is suspect, too.

A count to about -6- before it gets too hot for your hand on the
thermostat housing is normal operating temperature. Maybe the pee
stream on the colder engine is weak because the thermostat is stuck open
or someone has removed it.

Rob

trainfan1 wrote in message ...
Eldon Cutlip wrote:

I took the thermostat out of the "hot" one and then ran it on the
"ears." The engine stayed dead cold for as long as I ran it (probably
a few minutes). But the pee hole just dribbled a drop or so every few
seconds - no stream. Then I put the thermostat back in and it had a
good stream at the pee hole but the engine started heating up again.
Should I still get a good stream even with the thermostat out - if the
water pump is good? I know the powerhead was getting water because it
stayed dead cold and I saw water when I pulled the thermostat cover.

Thanks,
Eldon

trainfan1 wrote in message ...

Eldon Cutlip wrote:

I recently purchased a boat that has 2 1986 Johnson 70 motors on it.
On the first run out we noticed that the temperature guage for one of
them went up to the top of the red while the other stayed in the
bottom 1/3rd of the green. We stopped the motors and took the covers
off and put our hands on both of the heads near the spark plugs. The
one that had stayed in the green was barely warm and the one that was
in the red was hot enough to bother your hand if you left it resting
on it for 30 seconds. We had actually never gone more than about 1/3rd
throttle on either engine for no more than about 5 minutes. And the
one in the red had only been at idle except for about 30 seconds when
I had put it up to about 1/3rd throttle. The pee stream on both motors
looked good. But on the one that was in the red, the pee stream was
even stronger - actually stronger than I have ever seen on outboards.
I replaced the thermostat because I was thinking that the impeller was
good because the pee stream was so good. But it still climbs up to the
red after just a few minutes at idle - and then the powerhead feels
hot to the touch - not like it burns your hand - but again
uncomfortable if you leave your hand on it for a while. Any ideas what
the next step should be? I called the local boat guys and they are all
at least 2 weeks out and halibut season opens Thursday - so I would
like to get a chance to use the boat before 2 weeks from now.


Thanks,
Eldon

If you can hold your hand on it for 30 seconds, it's actually running
cold. It sounds like the gauge is inaccurate. There was no factory
provision for sending units on these engines except for the warning horn
switch, so the installation is suspect, too.

A count to about -6- before it gets too hot for your hand on the
thermostat housing is normal operating temperature. Maybe the pee
stream on the colder engine is weak because the thermostat is stuck open
or someone has removed it.

Rob

With the thermostat out the pressure will fall off. Hence my suspicion
of your "cold" motor. The thermostats should be closed, or
substantially so, until around 150 degrees, and then they will let 150
degree or warmer water by. You can test them on your kitchen stove with
a candy thermometer if you must.

Where are your sending units?

Rob

I don't know where my sending units are. For the Mercury engines I've
had I always got a nice shop manual for the specific engine from
Mercury. I haven't had a chance to get one for these Johnsons yet. I
do see a wire coming out of the power head just left of the thermostat
that I was guessing might be it.

I was thinking that even with the thermostat completely removed that
the pee hole should still have a stream of some kind - so I was
thinking my water pump was suspect. Are you saying that with the
thermostat completely out the pressure is reduced enough so that the
pee hole may just dribble (with no stream) and my water pump may still
be good?

If so, maybe I should just replace the thermostat on the cold one and
see if it "warms up?" If it does I could then do a "hand test" to see
if they are both pretty close to the same heat range? And I could
also see if their guages start reading close to the same heat range?

Unfortunately these thermostats are weird plastic ones that I've never
seen before and I don't think I would be able to see anything if I
boiled them. And more unfortunate is I won't be back home until
Friday evening to continue working on this.

I really appreciate your help. I haven't really even got a chance to
try this boat out because of this problem and I'm really dying to. I
did schedule an appointment in 2 weeks with the mechanic. But the
sooner I can get it worked out the sooner I can try out the boat

Thanks,
Eldon

I don't know where my sending units are. For the Mercury engines I've
had I always got a nice shop manual for the specific engine from
Mercury. I haven't had a chance to get one for these Johnsons yet. I
do see a wire coming out of the power head just left of the thermostat
that I was guessing might be it.

I was thinking that even with the thermostat completely removed that
the pee hole should still have a stream of some kind - so I was
thinking my water pump was suspect. Are you saying that with the
thermostat completely out the pressure is reduced enough so that the
pee hole may just dribble (with no stream) and my water pump may still
be good?

If so, maybe I should just replace the thermostat on the cold one and
see if it "warms up?" If it does I could then do a "hand test" to see
if they are both pretty close to the same heat range? And I could
also see if their guages start reading close to the same heat range?

Unfortunately these thermostats are weird plastic ones that I've never
seen before and I don't think I would be able to see anything if I
boiled them. And more unfortunate is I won't be back home until
Friday evening to continue working on this.

I really appreciate your help. I haven't really even got a chance to
try this boat out because of this problem and I'm really dying to. I
did schedule an appointment in 2 weeks with the mechanic. But the
sooner I can get it worked out the sooner I can try out the boat

Thanks,
Eldon

You should have metal OMC# 396987 143 degree thermostats in those
engines. This is a recirculating system, and at low displacement speeds
(the water pump - not the vessel) you will have a drop in pressure as
your "warm" water is wasted out the exhaust relief and exhaust hub
without the thermostat in place. It may even be low when the pump
reaches centrifugal speeds.

Put known good thermostats in and check your water jacket temp. I think
you will be alright.

Rob

On 2 May 2004 09:03:36 -0700, (Eldon Cutlip)
wrote:

I took the thermostat out of the "hot" one and then ran it on the
"ears." The engine stayed dead cold for as long as I ran it (probably
a few minutes). But the pee hole just dribbled a drop or so every few
seconds - no stream. Then I put the thermostat back in and it had a
good stream at the pee hole but the engine started heating up again.
Should I still get a good stream even with the thermostat out - if the
water pump is good? I know the powerhead was getting water because it
stayed dead cold and I saw water when I pulled the thermostat cover.

Thanks,
Eldon

Snip.

Why not remove the thermostat out of the good engine, and see if it
follows the same pattern?

Also, try switching the themostats. It's possible the new one could be
faulty, and double check that it's inserted the correct way (I'm not
familiar with that type).

If the bad motor still runs hot, maybe the impeller is worn & can only
move a small volume of water through the pee hole. Once the thermo
opens and a larger volume is required, it can't handle it. (like
squirting a jet of water with a water pistol, 20 feet with you index
finger is easy, but try and do that same distance with a garden hose
and you'll need to use your foot).

Cheers.

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.