Bilge Blower

[MarieK]

I have an extremely loud bilge blower in my boat. It runs continously from the moment ignition is turned on. A friend has the exact same boat albeit and older model and his bilge blower comes on for maybe 1 minute every so often. Which is correct? I dont like the noise, would prefer to only having it come on every so often!

Thanks
Ryan

 

[jhr]

My bilge blower is operated by an on/off switch from the dashboard and I usually run it for a few minutes before starting up (having first checked that the engine bay doesn't smell of petrol /forums/images/graemlins/smile.gif) and then at any time when I am running slowly. That's what the handbook suggests.

However, I guess it depends on what engine you've got and why the blower is primarily there - just to clear fumes from the bilges, or to help air supply to the engine? Also may be different for diesel engines? My mechanical knowledge is limited, so treat this advice as being worth what you paid for it!

 

[Blackfeather]

I have a bilge blower on ours but with twin diesels wonder what the point is?

 

[Mymobo]

I have the same system as JHR and use it in the same way.

 

[Blackfeather]

Ours is on permanently whenever the ignition is on. It sucks air out so i don't see how it can help aspirate the engines. Am I missing something (I usually am).

 

[mainshiptom]

I have never switched mine on, it make a right party !

 

[rafiki_]

With petrol engines it is prefereable to run the blowers all the time, to reduce the risk of fire/explosion, especially carburetted engines. With diesels, it is sensible to blow for 1 min prior to starting, in case there are any residual gases in the engine room that could cause a problem, but once clear, a diesel is unlikely to produce flammible gases.

 

[Wino]

In view of the massive quantities of air drawn into the engine I can see no use for a blower once the engine has started?

 

[MarieK]

So am I correct in saying that its not normal for the bilge blower to be running all the time? I am going to put a switch on it and only fire it up before I start the engine.

 

[neale]

Most modern diesel boats I have been on recently have engine fans that run all the time.

 

[CMJ]

Yep, a dilemma I've been having recently. Our diesel boat has extractor fans that come on automatically with the ignition sucking air OUT of the engine bay, and ventilating fans that blow air IN to the engine bay (that are on a switch). The weird thing was that for the first two years of owning the boat I assumed that the ventilators came on automatically too(rather than being on a switch) and as the ventilator warning light was broken, I never knew and therefore the ventilators were never on. These days I run the ventilators all the time by turning on with the switch and therefore both ventilators and extractors are always on.

......the manual doesn't clarify whether the ventilators should be on or not (whether automatically like the extractors, or on a switch), so I just play it safe……but the boat seems to run just the same regardless of whether the ventilators are on....

God – reading my boring reply back to myself almost sent me to sleep, SORRY!
/forums/images/graemlins/crazy.gif /forums/images/graemlins/crazy.gif /forums/images/graemlins/crazy.gif

 

[Its_Only_Money]

[ QUOTE ]
In view of the massive quantities of air drawn into the engine I can see no use for a blower once the engine has started?

[/ QUOTE ]

Indeed! Say 5L petrol engine at 3000rpm consumes approx 3750L per min of air. 1 cu ft or air is approx 27L so the above example if my maths is holding out is consuming around 130cu ft per min.... my engine bay runs to about 100cu ft so I get a full engine bay air change approx every 45secs - far far quicker than the bilge blower could ever achieve.

I run a hydrocarbon detector that will detect petrol fumes at around 20% of the level at which they become dangerous and will run the bilge blower as a precaution. Under testing it usd to run the blower after shutdown due to some natural fume leakage from the carb but since changing the engine to Fi it doesn´t trigger. Still manually run the blower before startup and after shutdown but nice to know there should be a warning of fumes and it will trigger the blower if needed.

Remember to check you have a pipe to ensure the blower can draw from low down in the bilge where the first fumes will gather....

 

[markdj]

For petrol boats:

An extractor is run for a few minutes but should be off when the engine is running.
A blower is run continuously to bring in fresh cool air for the engine.

For diesel boats:

A blower is run continuously to bring in fresh cool air for the engine.

Any extractor should be off when the engine is running as I would think this is counterproductive to the engines' combustion.