4.3 Mercruiser venting question

[kcruth]

Hi folks, proud new owner of a 2007 1800 SR3 here. I am new to I/0s and have a question about venting; there is a 4" (I think) vent hose attached to the rear side of my motor, then another 4" that is lose and looks like it should be at least attached through a hole in the battery compartment divider into the engine compartment, right now it's just hanging into the battery compartment; if the pictures work the one without my hand is how it is currently, and the one with my hand in it is how I think it should go. Is it correct that it's just a vent into the engine compartment and I should just find a hole adaptor to get it to stay in the hole, or is it actually supposed to attach somewhere other than just going through the divider hole?

Thanks much for any help you can give me!





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[mmwjr]

Welcome aboard.

I cannot view your pictures from work so I will look tonight but from what you describe it sounds like the engine compartment vent hoses. There should be a blower that has its input hose going to the lowest point in the bilge to draw and potential fumes out and the output hose should be connected to a vent grill either on the back or side of the boat. There should also be a fresh air intake hose connected to a vent on one end and then anchored to the deck near the engine. Try googling how to install a blower on a boat and you can see diagrams on this.

[kcruth]

Thanks much for the reply!

There are two hoses. One is what you describe, going from apparently a pump in bilge area to side of boat vent. There is a second hose that also terminates at the vent, but it starts simply loose in the compartment next to the engine compartment and looks like it originally went through a hole into the engine compartment.

[mmwjr]

Looked at your pictures, yep one is just a direct run to allow fresh air in the the other is connected to a blower to evacuate fumes. Run the blower for four minutes prior to stating the engine.

[kcruth]

Right, but shouldn't the fresh air vent terminate in the engine compartment (the pic with my hand holding it there) rather than in the next door battery compartment (other pic)? That's the question; it looks like it should go through the hole into the engine compartment but it's just flopping lose in the battery compartment.

[mmwjr]

Originally Posted by kcruth

Right, but shouldn't the fresh air vent terminate in the engine compartment (the pic with my hand holding it there) rather than in the next door battery compartment (other pic)? That's the question; it looks like it should go through the hole into the engine compartment but it's just flopping lose in the battery compartment.

Yes they should both be in the engine compartment, the intake higher than the exhaust hose as gas fumes settle to the lowest point.

[shrew]

Looks like blower hoses to me. IS there a small blower attached somewhere in the path?