1994 2 stroke over heat alarm

[Aussyedo]

Hi Guys,
I have a 1994 model johnson 90hp 2 stroke outboard.
It has been running fine but last weekend when i fired it up it ran for about 10 minutes before the over heat alarm activated.Water was pumping fine.
Let it cool, started it up water pumped fine and then the alarm sounded again so i shut it down and let it cool. 3rd time i started it i kept an eye on the water strwam out of the tell tale and it was pushing out like normal but then it started to come out intermittently and i new the alarm was going to go off so i shut it down. I was running the motor on muffs with a good constant water supply. at first i thought it may have been something to do with the fuel as the exhaust smoke smelled really oilly and the fuel would be a few months old in the under floor tank but then the water jet from the tell tale was sporadic.
Any ideas folks??????????
Edo

[Solarman]

How long since water pump was replaced, thermostat(s)?
If tell tale starts spitting it probably is getting hot. You may have a bad impeller in pump, thermostat(s) could be sticking, or water pas-sages could be blocked up.

Also, make sure your oil system is working. Could try a portable tank if you think fuel is not good?

If water pump is good, you might try running a salt corrosion cleaner through motor to clean the water channels.

Post back when able, to let us know how it's going.

[Aussyedo]

reply

Thanks for the information.
The impeller was replaced at its last service approx 14 months ago.
I have owned the boat 2 years and havent replaced thermostats or water pump in that time.Motor is being serviced early next month so will see what the issue is.I dont think it is bad fuel anymore, although the fuel is old, because it had usual pressure out of the tell tale for the first few times i started it on sunday.It only started spitting intermittently after i let it cool and started it the third time and when i saw it wasnt constant i shut it down.
Edo

[Solarman]

The impeller is water lubricated, anytime the flywheel turns the impeller should have water on it. It only takes a second or two if dry, for the impeller to fragment. If it fragments, then there's a good chance pieces can block pas-sages. If water has always been on impeller when started, then good chance thermostat(s) may be sticking shut. Or, some of the pas-sages are blocked, and flushing in a barrel with salt away, or other salt corrosion remover additive, for an hour or two would be best approach.

Good luck, let us know what happens.

[Aussyedo]

Guys,
Just had it serviced, replaced water pump and housing etc.
Turns out my muffs werent holding seal well enough which was the cause for the over heat alarm, it simply wasnt getting enough water, been running those muffs for 2 years and never had that problem before so didnt think that was the problem but it was, took it for a run after the service in the local river and it ran well with no over heat alarms activated, thermostats are working well, ime off to buy some new muffs
Edo