Coolant & your outboard

[Justinde]

Just wondered if you can use coolant when flushing your outboard- maybe diluted, run in a barrel, then run fresh water until all coolant is expelled from the engine? It is an anti corrosive, and, well, salt water is corrosive. Would this harm the waterpump/block/powerhead? Has anyone done it before and failed or succeeded? Is it the worse idea on the planet? Feedback & Comments appreciated.

Cheers

 

[jerryjerry05]

Re: Coolant & your outboard

Flushing it with antifreeze is a good idea if your in a freeze zone.Otherwise just flushing with fresh water is all that's needed.The only place that water stays in the motor is a small amount in the pump.Most outboard are self draining if left straight up and down.
Once you flush the salt out and the water drains out,that's when the corrosion really starts.
Corrosion gets worse when the water is gone.Air makes it worse.
Your motor the place that salt affects the most is the head gasket.It heats up and expands,then cools down before U flush it.Leaving some salt in the crack and crevices.
Unfortunately one of the things in an outboard that rusts is the liners in the head.The rest is usually made of aluminum.
Not flushing is the WORST thing U can do.
Had a customer who inherited a 175Johnson.Left in the water on a lift.Never flushed.Started overheating at speed and couldn't figure out why.New impeller and thermos.
Turns out the salt/sediment ate through some passages and the power head was shot.
Hope this helps.
When flushing,make sure it runs long enough that the thermostat opens.Jerry

 

[Frank Acampora]

Re: Coolant & your outboard

Couldn't hurt, but remember: Anti-freeze is designed to protect an auto engine which will most likely never see salt. So, it is designed to protect from a differet type of corrosion.

I don't know if they use anti-freeze in closed loop (Heat exchanger, fresh water cooled) IO applications but if they do, then this very expensive marine grade coolant may be a better alternative than auto grade.