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Old March 31st 04, 04:10 AM
mike
 
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Default 1982 evinrude 25 lower unit swap and operating temperture qusetion

I have an old 25 hp evinrude outboard. I want to remove the 5 inch
extension to shorten the shaft. To use my current lower unit, I need
a drive shaft and I have to install the drive shaft. I don't know how
to seal the lower unit and put every thing back together. I was
wondering what lower units will swap out. I also want a lower unit
with through prop exhaust.
My other question is about how to measure operating temperture.
I know its around 170, but there is no overheat warning horn. What is
an easy way to measure the temperture. They have plastic sticks that
melt but I cant find them easily. What can I use to check the
temperture easily to get an idea if I need to change the water pump
and thermostat.

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Old March 31st 04, 05:58 AM
trainfan1
 
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Default 1982 evinrude 25 lower unit swap and operating temperture qusetion

mike wrote:
I have an old 25 hp evinrude outboard. I want to remove the 5 inch
extension to shorten the shaft. To use my current lower unit, I need
a drive shaft and I have to install the drive shaft. I don't know how
to seal the lower unit and put every thing back together. I was
wondering what lower units will swap out. I also want a lower unit
with through prop exhaust.
My other question is about how to measure operating temperture.
I know its around 170, but there is no overheat warning horn. What is
an easy way to measure the temperture. They have plastic sticks that
melt but I cant find them easily. What can I use to check the
temperture easily to get an idea if I need to change the water pump
and thermostat.


I don't consider your outboard old yet.

If you have the parts, this can be a DIY project without too much
trouble - as long as you are patient with the "spaghetti" seals.

If you still want to avoid the job, you can use the short shaft lower
from the 82-84 20hp, 79-84 25hp, and the 1978 & newer 28hp / 28SPL. I
think the SPL only came in a 20" shaft, though.

There is no direct bolt-up for the thru-prop exhaust... the 30 & 35 hp
motors use a different leg & exhaust housing, and a recirculating
cooling system.

How to check for proper temperature... my on the water quick-reference
method:

When the outboard is up to running temp, grasp the thermostat housing
with your hand and count how many seconds it takes until the heat
becomes just unbearable to the point you have to let go before getting
burned... this will be about 4 1/2 seconds for 155/160 degrees.

CAUTION: this can be very dangerous! I used this shortcut when I
maintained a fleet of 70 or so rental boats and had no time to run for a
Thermomelt stick every time we had to check for water pump & thermostat
issues. I never got burned, but it was usually very obvious if an
engine was running really hot.

Good Luck! That is a nice engine to have that will serve you well for
years... even more versatile if you keep all the parts to switch back &
forth from short shaft to long shaft.

Rob
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Old April 1st 04, 02:55 AM
LD
 
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Default 1982 evinrude 25 lower unit swap and operating temperture qusetion

Are you sure yours is an '82? I have an '81 (J25RCIM) which I've been told
on several occasions that it's the last year before the through prop
exhaust.
If you do get the through prop exh let me know what you want for the "old"
foot and gears. I use mine for duck hunting and am a little rough on it.
LD

"mike" wrote in message
om...
I have an old 25 hp evinrude outboard. I want to remove the 5 inch
extension to shorten the shaft. To use my current lower unit, I need
a drive shaft and I have to install the drive shaft. I don't know how
to seal the lower unit and put every thing back together. I was
wondering what lower units will swap out. I also want a lower unit
with through prop exhaust.
My other question is about how to measure operating temperture.
I know its around 170, but there is no overheat warning horn. What is
an easy way to measure the temperture. They have plastic sticks that
melt but I cant find them easily. What can I use to check the
temperture easily to get an idea if I need to change the water pump
and thermostat.





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