1990 Sport Nautique Exhaust

[cuwakeboard]

I recently purchased a 1990 Sport Nautique. There seems to be a abnormal amount of exhaust coming from the transom at cruising speeds. This does not happen at an idle, only at the higher speeds. Is this normal, or am I just paranoid?

Thanks, Eric

[8122pbrainard]

RE: 1990 Sport Nautique Exhaust

Eric,
I think your paranoid! When you say "abnormal amount", is this white "smoke"? If so, it's water vapor being condensed by the cooler ambient air temps you are seeing this time of the year.

[TravisFling]

RE: 1990 Sport Nautique Exhaust

I was just going to say the same thing... remember - White = steam (vaporized water from the heat of the engine) and is perfectly normal. Blue means you're burning oil, and isn't horrible (you can drive back to the dock, being mindful of your pressure.) and Black means you're burning excess fuel (not combusting in the cylinder, but burning later in the stages of stroke/exhaust.)
White "smoke" is most notable at cruise as the engine's producing enough heat to vaporize the water, but the air "eddy" is just right to allow it to hang around. At quicker speeds the airflow causes the vapor to disperse too rapidly to be noted too much.

[cuwakeboard]

Thanks guys. I have one more question -

I bought the boat from a guy located close to Lake Powell (elev = 3700) and will use it extensively in the rocky mountains (elev = 5000-7000). Do I need to due a tune-up to account for the change in altitude? Thanks.

[AuMDLST]

I'm thinking you may want to have the carb adjusted for the altitude difference (I believe less oxygen would make it run on the rich side) - Someone else with better carb knowledge will most likely post with a definite answer.

[AirTool]

I would say that if it idles smoothly to not mess with it.

[AirTool]

I would say that if it idles smoothly to not mess with it.

Otherwise, without looking at the carb....you would probably have to change the jets.

I don't see any other "tune up" adjustments to compensate for the low air density.