1997 25hp johnson outboard. white smoke at idle?

Question

I have a 25hp 2stroke outboard on my boat and it puts out white smoke like crazy at idle. what could cause this. it just started this month. has new plugs are about three months old. Fuel is never more than a week old

Answer 1

With the cooler temps out there they will steam mixed with smoke>Sometimes even in Florida>Your thermostat could have issues?Water pump week??Easy fix>

Answer 2

make sure that the thermostat is working properly and is in place some people think that thermostats are not necessary. if yours is stuck open or missing the engine is not running hot enough at idle for complete combustion. if water spits out the small exhaust relief hole(back of motor below hood latch on exhaust hsng) not the water indicator, as soon as the engine starts then the tstat is probably stuck open/missing. this will cause smoking and can cause you to foul spark plugs faster. you should also check the primer/choke valve to ensue that it is fully pushed in after engine starts or fuel can bleed thru causing the engine to run rich at idle.(rope start models) if remote or electric start make sure that manual primer valve(red lever) on electric primer under the hood is in the correct position as this also will cause extra fuel to enter the engine.

Answer 3

White smoke is an indication of water in the combustion chambers. What your seeing is steam.

Not sure if that particular outboard is water cooled, but if it is it's quite possible that you are experiencing either a cracked head, a cracked water jacket, or a simple bad head gasket.

But by your description, your definitely getting water in there somehow.

Good Luck.

Answer 4

water getting into the motor. Dab some oil from the motor in a white paper towel. Look for water ring around the oil drop. Filler cap leaking or head gasket.