Ive had outboards or diesels for a while but I'm getting back into a petrol sterndrive. Previously with inboard petrol I'd open the hatch and run the blowers for 3-4 minutes then start engines, run a minute or two before closing the hatch and I'd turn OFF the blowers. I'm now thinking that as long as the engine is running, shouldn't the blowers be turned ON?

Petrol fumes are heavier than air so with the hatch closed, any petrol fumes are 'trapped' in the bottom of the engine bay, so blower intakes are located low down.

Maybe a stupid question but do you run your bilge blowers all the time?

RR

I open the hatch to give a check, Turn blowers on for a minute or so, start engine, lower hatch. The only other time i keep them on is while refueling.

Same here!

I don't run them as much as I probably should... definitely have never run them while running on plane.

Never had an issue but I probably should make it more of a habit.

I run the blower for a few minutes, start motor, then turn it off once I start moving. One less moving part I have to worry about now that I have OB's.

Run em. Those things are cheap to replace when they wear out, so run the dog piss out of em. Ain't going to hurt a thing.

Formula does not have the greatest venting so I run mine all the time to keep the engine room temperature down. Jeff wurl

I tend to run mine a little more often when it's really hot/humid - especially when idling in to a bay for a raft up (hopefully helping to cool bilge/engines somewhat). Damn 700's and vapor lock .

As long as you make sure they are on a fused circuit, which of course they should be whoever installed them. I have seen them melt/smolder before. But yes, run them at every start up; and visually inspect the bilge every new day of boating, or after every longer break. (After a raft up, after a meal, anything over an hour or so.)

So are a lot of you guys actually running them all the time? I guess I never considered it could help with engine bay temps