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Today while replacing my blower on my just purchased Columbia 8.7 I noticed the hose connects to the top of the engine housing and the intake is at the bottom. I would think it would be the other way around.
 

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formerly 'BoatyardBoy'
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The intake is at the bottom to remove any heavier than air low lying gases or vapors that may be in there.. It should blow the fumes out of the boat somewhere.

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Old as Dirt!
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Today while replacing my blower on my just purchased Columbia 8.7 I noticed the hose connects to the top of the engine housing and the intake is at the bottom. I would think it would be the other way around.
The hottest air/fumes in the engine compartment will be at the top while the engine is operating. One wants to remove that and have it replaced by cooler clean air that will be drawn into the bottom of the compartment by static air pressure. In most cases, you will want roughly twice as much intake vent area as you have discharge through a properly functioning vent/blower. If your engine is gasoline powered, you may need an intermittent blower/vent to the bottom of the compartment to run for a few minutes before attempting to start the engine as a matter of safety. Unless your boat has some serious defects, there will be no way that Propane fumes can reach the engine space. If they can, however, you have much more to be concerned about than where the exhaust vent is positioned.
 

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If your engine is gasoline powered, (note: gasoline fumes are lighter than air) you'll want to run the blower for a few minutes before attempting to start the engine as a matter of safety. Unless your boat has some serious defects, there will be no way that Propane fumes can reach the engine space. If they can, however, you have much more to be concerned about than where the exhaust vent is positioned.
This is absolutely untrue !!!!!!!!!!

Gasoline fumes are heavier than air and this is why ABYC requires that blower exhaust ducts terminate as near under the engine as possible while remaining above normal bilge water levels.

Strongly suggest you read Safe Gasoline Engine Compartment Ventilation
 

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Old as Dirt!
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This is absolutely untrue !!!!!!!!!!

Gasoline fumes are heavier than air and this is why ABYC requires that blower exhaust ducts terminate as near under the engine as possible while remaining above normal bilge water levels.

Strongly suggest you read Safe Gasoline Engine Compartment Ventilation
Actually you are correct and I shall make the appropriate change to my earlier comment.

Done!
 

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For gas engines, the blower exhaust intake must be at a low point in the engine compartment. As others have noted, gasoline vapor is heavier than air and extremely explosive.

For diesel engines put it near the top where the heat is concentrated, and if possible near the alternator (which is adversely affected by excess heat).

Loren
 
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