Engine blower, Yanmar 4JH4AE

[JohnB40]

Hi
Boat is Beneteau 40 (2009) with above Yanmar engine. There is a small blower screwed to transom that blows air through 4 inch plastic ducting into the engine compartment. There are two similar ducts that presumably direct the air from the engine compartment back out.
This blower has broken and would be VERY VERY hard to get at and replace. Do I need it? That is, what's it for?
Someone suggested engine might overheat but all seems OK. Could it just be to ventillate any engine fumes out the back?
Thanks for any help, JohnB40

 

[Calif. Ted]

It is not required for diesel engines, with seawater temps in BC it probably doesn't affect cooling much, more if you were in the tropics. I like to run it to help remove excess heat in aft compartment and some airflow, but their necessity is usually subject to debate on these forums.

 

[Herrick18911]

It's more of a holdover from gas engine days. It isn't necessary (haven't used mine in a long time).

Tod

 

[kloudie1]

Blower is useful in cooling the engine compartment down here in the summertime A hot engine will noticeably warm the cabin .. In your area, that might be a good thing..

 

[Ralph Johnstone]

There is a small blower screwed to transom that blows air through 4 inch plastic ducting into the engine compartment.

As others have said, it's used for either engine compartment or cabin cooling. There is no need for vapor removal as with a gas engine.

The way you describe the flow, it's in backwards as you want to pull air into the engine compartment. Blowing air into the compartment will force hot engine smells into your cabin space. the outlet hoses do nothing unless the engine compartment is sealed.

Hard to say why it was installed in the first place. If the lack of it isn't causing a problem, best to forget it.

I'm currently installing an exhaust fan in my engine compartment to cool my alternator (but with noise problems). I had recently installled an external alternator regulator and for the first time in its lazy life, the alternator is actually having to do some work and its really getting hot. Normal engine compartment temperature is 150 deg. F which is not healthy for alternator cooling.

 

[Scotty C-M]

Your boat does have, however, a propane system. If a leak occurred in that system, you might use that blower to ventilate the engine compartment prior to starting.

 

[Doug4bass]

All Catalinas have this blower installed. Helpful to ventilate the engine compartment during extended operation. Also fresh , cooler air for the diesel intake.

 

[Stu Jackson]

The only reason they're there is 'cuz they were made for gas engines and they never bothered to take 'em out!

Skippers have found secondary uses for them.

 

[Doug4bass]

Nice thread from a couple of years ago.

http://www.sailnet.com/forums/gear-maintenance/91156-diesel-engine-compartment-ventilation.html

 

[petersea]

OK here is another take on this...........agree it is not mandatory for diesel engines but useful for secondary cooling of engine compartment. AND here is the twist........ fix it or remove it. IF you go thru a survey for any reason it will be noted as a defect if installed and not working. If you have your boat inspected by Coast Guard or locals a overzealous officer will note it as defective. SO either remove or repair.

 

[Benny17441]

I would not think they were installed to ventilate propane. I don't know if those blowers are spark protected. Propane gas is heavier than air and will flow, similar to water, to the low point in the hull which is usually the bilge. When pooled and in a large concentration any electric motor producing a spark can set it off. The idea is good but, Propane does not ventilate well.

 

[Ken13559]

If i have one on my boat, i would place the ducting near the alternator to draw air pass it for cooling. A cool alternator has higher charging current/voltage.