Boat Builder Central - Builder Forums

The motor has been running like a top.
Always flushed after every use with no
problems. Yesterday after a short little
trip the buzzer goes off. Now the motor
will only run about 3-5min before the
buzzer sounds and I shut off the motor.
It has a good steady water stream, however,
it may take a couple of seconds to discharge
when you first start the motor. Starts off
kinda weak then picks up really strong.

More than likely, the impeller for your water pump is shot. You have to drop the lower unit to replace it and it's not really that difficult. If you've never done it, check the local library for outboard repair manuals. Most of the lower units are almost exactly alike and if you can find one manual w/the procedure, you're good to go. If the impeller housing has any dings in it, replace it also. Sometimes, the water pump kit is actually cheaper than the individual parts, but none of them are big price items.
A lot of the time, the impellers are ruined before the motor gets in the water. Some folks like to start the motor just before launching for a few seconds. Thats all it takes, 'cause the impeller is lubed by the water that it's pumping. They will still pump, but the ends of the blades have been hardened by the excessive heat and won't hold a seal as well.
Be happy that the buzzer is going off. Could have been real spendy if it hadn't.
Good luck.

On an engine that old, I'd replace the impeller & thermostat.

Patric has it right on DON'T RUN THE ENGINE WITHOUT WATER.

Don't ask me how I know this

The engine is getting water, it has a steady
strong stream. I'm going to trake out the
t-stat today and see what it does. I would
have to guess you can run one without a t-stat
in it like you can a car.

The engine is getting water, it has a steady
strong stream. I'm going to trake out the
t-stat today and see what it does. I would
have to guess you can run one without a t-stat
in it like you can a car.

Try these folks. The depth of knowledge is truly remarkable. I'd ask them before I started to remove parts.


http://forums.iboats.com/cgi-bin/ubb/ul ... forum;f=28

I bet its the thermostat. If its corroded, it wont open enough. The other thing is a bad buzzer. If you can hold your hand on the block and keep it there without getting so hot you have to take your hand off - its cooling enough.

I love those engines - so easy to work on your self.

Don't trust the stream to show that it's pumping enough water. I had one old outboard that I got that did the same thing as you're describing (stream started as a trickle and within 15 or 20 seconds appeared to be pumping good), but it still seamed to be running hot. When I took it apart, I found that only one of the impeller blades was still attached - and just barely.

One more thing. I found when I serviced my engine, that the some of the water channels were completely blocked up with sand and broken shell material (around the tstat areas). Give them a really good blast with water. If the tstats are corroded, replace, its false economy not to.

The motor had zero corrosion in the cooling jacket, the
t-stat was sticking but wasn't really in that bad of shape.
Talked to several mech's in the area that have a good
rep they all say about the same on putting a new t-stat
in, some work fine without some don't .... It really
depends on the motor from what I am getting.

I will find a rebuild kit for the pump rather than just replace
the impeller. That seems to be one thing all the mech's
agree on, because I have no idea when that may have been
done last. I know the motor sat for 12-15 years with no use
at all before I got it. It compression test the same as a new
one so its not hardly even used.