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Beneteau 331 engine room fan

Jul 14, 2020
8
Beneteau 331 Lake Conroe
I just bought this boat, Yesterday I accidentally knocked off the engine room fan cowl at the transom when I disconnected the shore power. When I put it back on I noticed that air is being sucked in at the transom rather that being blown out. Is this correct or is this fan wired backwards? Thanks!
 

DougM

.
Jul 24, 2005
1,887
Beneteau 323 Manistee, MI
There should be two cowls...one duct functions as an inlet and the other as the outlet. On my boat those cowls are a typical aftermarket part. Try the SBO site here as a possible source. (since you appear to be somewhere in Texas and there may not be a marine store around, try an RV supply store.)
 

dmax

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Jul 29, 2018
203
O'Day 35 Buzzards Bay
The fan should definitely be sucking air out of the engine room - much easier to pull air than to push it.
 
Nov 21, 2007
341
Beneteau Oceanis 34 Tacoma, WA
I think my fan pulls air in through two small vents at the companionway. I'd be worried about diesel exhaust fumes and CO if it pulled air in from the transom. Plus, if the motor is running in reverse, I wouldn't think that it would be moving much air at all anyway. ¯\_(ツ)_/¯
 
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Jan 4, 2006
2,964
Hunter 310 West Vancouver, B.C.
The fan is definitely blowing backwards as pointed out by @SoSound . Could be deadly in reverse with a CO leak from the engine.

Depending on the path of the incoming air, you want the incoming air to be sucked along the hull, through the bilges, and what have you in order to cool the air. The sole purpose of the air is to cool the alternator. The diesel is a lean burn engine so it has air to spare.
 
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Likes: sf34dtw
Jul 14, 2020
8
Beneteau 331 Lake Conroe
I figured it was backwards. Definitely seems like a hazard to blow air into the engine room and disperse it throughout the vessel.. It has probably been like this for years but I will reverse it before I take her out again.
 
Jan 22, 2008
7,647
Beneteau 323 Annapolis MD
Just last night I looked in my owners manual. It shows the vent hose as an EXHAUST vent, picking up air on the engine room, blowing it out the stern.. ...... see post 13, though.
 
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arf145

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Nov 4, 2010
391
Beneteau 331 Deale, MD
My 331 (hull #2) doesn't have an exhaust fan--I don't know that it ever did. I always thought the duct tube running into the engine area was for intake air.
 
Jan 22, 2008
7,647
Beneteau 323 Annapolis MD
My 331 (hull #2) doesn't have an exhaust fan--I don't know that it ever did. I always thought the duct tube running into the engine area was for intake air.
are you SURE there's no fan? It probably would not be in the engine room itself.
 

arf145

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Nov 4, 2010
391
Beneteau 331 Deale, MD
No, I definitely couldn't swear to it, especially if it automatically runs when the engine runs and is located in the stern.
 
Nov 2, 2008
105
Beneteau 331 Chicago (DuSable)
No, I definitely couldn't swear to it, especially if it automatically runs when the engine runs and is located in the stern.
My 2002 #226 all does not have a fan. At least not one I ever heard. I'll have to check on the Beneteau Parts.
 
Jan 22, 2008
7,647
Beneteau 323 Annapolis MD
are you SURE there's no fan? It probably would not be in the engine room itself.
My 2006 3ym20 turns the fan on when the key goes to "on". The engne was not running, so I could not tell at the transom if it was blowing or sucking I'd have to go with "sucking " in spite of the "exhaust" labeling in the engine manual when the engine runs.. The engine end of the hose ends a few inches from the air filter/horn intake. It was too dark to see, but the fan itself is about 2/3 to 3/4 of the way to the transom cowl.
 
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arf145

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Nov 4, 2010
391
Beneteau 331 Deale, MD
I think I'll check that out...later, when I can do it without filling my bilge with sweat!
 
Mar 20, 2016
357
Beneteau 351 WYC Whitby
The blower is wired to the ignition switch and should turn on first before starter and is located on the stern up hi
 

DougM

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Jul 24, 2005
1,887
Beneteau 323 Manistee, MI
The blower is wired to the ignition switch and should turn on first before starter and is located on the stern up hi
Having owned power boats with gasoline engines it became habitual to run the blower for awhile before starting the engine, and as part of the refueling ritual. Even though the sailboat has a diesel, I turn the key on and let the blower run before I hit the starter button. The blower is wired to run continuously while the engine is running.

When I first got the sailboat, I wondered why the fan was not wired with its own on/off switch. A 2 cylinder diesel certainly doesn’t inhale and need to exhaust as much air as a 350 Chevy V8 which sits under a smaller enclosure than the engine space in a sailboat...

The blower is off when the ignition is off, and probably should run for a time after the engine shuts down to help cool off the interior of the engine compartment. It does stay fairly warm there
 
Feb 21, 2010
265
Beneteau 31 St-Lawrence river
After a partial meltdown of the ignition wiring and after changing the whole harness once I rewired the exhaust fan and ordered a new one from Bénéteau.
The new fan is now manually controlled via an an-off switch located aside the ignition panel. I can run the fan for awhile after the engine is off and cool down the engine room which is just beside the our bed.
I prefer the manual control.
 
Jan 22, 2008
7,647
Beneteau 323 Annapolis MD
The blower is off when the ignition is off, and probably should run for a time after the engine shuts down to help cool off the interior of the engine compartment. It does stay fairly warm there.
That's one reason to let the engne idle when in the slip. To cool down.