Noisy Engine Compartment Fan

sun37 · #1 03-09-2008

Hi everyone,

Last summer I bought a new 37 foot sailboat that is powered by a Volvo Penta D40-2 engine with saildrive. When I start the engine, a fan turns on. It is very noisy and generates more noise than the engine itself when I'm in the cockpit. When I turn the engine off it continues to run for 10-15 minutes, still making a great deal of noise. Does anyone know if such a fan would be running on some sort of timer or if it deactivates after the engine compartment reaches a certain temperature? I am also wondering about the purpose of the fan. I heard that it sucks the fuel vapors from the engine compartment in order to prevent fires. I also heard that it cools down the engine compartment. There is no documentation of this fan in the owner's manual and the local dealer service does not seem to know the answers to my questions.

Thanks for your help,
Sun37

camaraderie · #2 03-09-2008

Sounds like a standard ventilation fan. No diesel exhaust is released into the compartment as it is contained within the water exhaust a channeled overboard. The fan in to provide a good flow of cool air to the engine which needs it for combustions AND to vent heated air overboard. You may replace the noisy fan with a quieter fan of similar capacity.

Giulietta · #3 03-09-2008

I also had a noisy fan. The one I had before was a centrifugal one.

I just got rid of it, and installed a quiter one. An axial one. They are pretty cheap.

I am looking for photos of it now.

Mine are wired so it only starts with the key in the ignition and power to the engine on, via the engine relay. I stop the engine, it continues, but if I take the key off the ignbition it stops.

Fans are good to provide air for the engine at higher revloutions, remove odours and cool the engine some.

Giulietta · #4 03-09-2008

Go here...click

Page 140 of the catalog

My fans are from Vetus an European manufacturer of excellent products..

This is what I had before..really noisy. This fan was installed in my stern inside a locker sucking the air of the engine compartment.

This is what I have now...also with this fan, I installed it inside the engine compartment, as it is spark protected on start. so instead of sucking the air, it blows the air out thru the same tube.

sun37 · #5 03-09-2008

Thanks camaraderie for suggesting a quieter fan and thanks Giulietta for the information and pictures. Looks like a quieter fan is the solution for my problem. Any ideas on how the fan shuts itself off when the engine is sopped? How long should the fan stay on after the engine is stopped? I guess it will depend on how hard the engine was running before it was stopped. By the way, I don't have an ignition key. The only way I can shut the fan off is by turning off the main DC breaker for a second and turning it back on!

Giulietta · #6 03-09-2008

You must have a relay on the engine don't you??

Have the fan wired to the realy, so that the fan is only on when the relay is energized.

And as soon as the engine stops, you don't really need the fan runing..that's an urban myth...

sun37 · #7 03-09-2008

I have a Volvo Penta EVC display. There is no relay to turn the fan on and off but I think I will install a quieter fan and ask the dealer service about an on/off switch for the fan.

sun37 · #8 03-20-2008

In page 140 of Giulietta's VETUS catalog, it says that the purpose of the ventilators is to extract the heat from the engine room after the engine has stopped (similar to a car's radiator fan I suppose). From this it seems that the blower should not be running when the engine is running, but only when the engine has stopped. Mine runs when the engine runs and for a while after it has stopped. It also seems that the blower should run till the engine room is cooled to a desired temperature, which would mean that there is a temperature measurement in the engine room. Giulietta, how when does the fan in your boat run, and how does it stop? I'd appreciate comments from other boat owners with engine room ventilators.

Thanks, Sun37

Gryzio · #9 03-20-2008

Quote:

Originally Posted by sun37

Hi everyone,
Does anyone know if such a fan would be running on some sort of timer or if it deactivates after the engine compartment reaches a certain temperature? I am also wondering about the purpose of the fan. I heard that it sucks the fuel vapors from the engine compartment in order to prevent fires. I also heard that it cools down the engine compartment. There is no documentation of this fan in the owner's manual and the local dealer service does not seem to know the answers to my questions.

Thanks for your help,
Sun37

I will say; With a Gasoline engine it probably for exhaust of fumes. Normally turned on manually with a switch 5-10 minutes before starting the engine.

With a Diesel it a Cooling Fan for the engine room. True, in a Sailboat of your size it not a big engine room, but, technically, it is a room!

My Brother's Motor Boat is Humongous!!!! 75 feet! I think the Beam is 12? Maybe 14? The Engine room and this IS a room! Has Twin Cummings and the Stacks sticking up have Humongous cooling fans inside!!! There some BIG stuff on this boat.

I can guess there smaller versions on smaller boats.

If it Gasoline/Petrol? This a Venting fan, should have a switch, but, over time someone may have hard wired to run constant thinking it more safe!

You have to learn how other people think. It not stupid, just this how that person felt, to be more safe!

If, it Diesel, I will assume it just a Hard Wire to run constant. Though I have seen elaborate hook-ups to cut on/off at different temperatures.

All I know is when I been down in what I call an Engine Room (Be it Power or Sailboat) ; It one Hot S.O.B. and after 12 hours running and 8 hours sitting, it still seem hot to me!

sun37 · #10 03-20-2008

Gryzio, you are right, what I have is 40 HP Diesel engine, and it's in a compartment rather than in a room. And since it's a Diesel engine, the fan is there to cool the engine compartment, and not for the exhaust of the fuel vapors - as written in page 140 of the catalog.

Sun37