3GM30F and a Bilge blower

[IanR]

I have a Yanmar 3GM30 F (Freshwater cooled) on my yacht, it has been fitted since new with a bilgeblower which I have replaced once because the old one died.

My question is as the bilgeblower vents into the cockpit it is in actual fact probably 3 times louder than the engine, a fact I noted the other day when moored next to a boat running engines to charge batteries. The noise is really starting to grate particularly on the odd long haul.

What would be the impact of turning it off, is it there for heat removal, air intake efficiency (cooler air more power) or fumes extract.

Or is there a quiter brand, I have a Vetus currently can I do anything to dampen the turbo fan??:??

I would rather be sailing in P&Q but sometimes passage plans force us.

?

 

[Salty John]

Bilge blowers are usually found in petrol engine installations, often wired so that they run for a few minutes to disperse any fumes before allowing the engine to be started. A bilge blower in a diesel installation can be useful to disperse bilge smells and generally vent the area but there is certainly no need to run one full time with the engine. My 3GM30F performed faultlessly in a cramped engine compartment in the tropics with no forced ventilation.

 

[tillergirl]

I would have thought that the bilge blower is there as an aid for clearing any gas leaks that might accidentally occur (assuming it has a sealed motor) or perhaps if you have a fridge compressor down there for assisting the removal of hot air from the bilge after a spell of motoring. I would have thought you had no need of 'cooler' air for extra power with that engine in your boat. And I would expect not to have to assist the engine cooling during 'normal' operation. As to fumes extraction - you shouldn't have any and if you have that should be tackled as a matter of urgency. I'd turn it off.

 

[oldsaltoz]

Blowers are used primarily to remove flammable fumes from from enclosed engine boxes, a typical installation would be a power boat fitted with an out-drive / leg / mercruiser etc.

Even they only run a few minutes before and after starting then are turned off, the air intake on the engine provides enough air flow too keep things cool and the air fresh, though not stone cold.

A 27.3 HP diesel engine will suck down an awful amount of air when running, so, provided you have no external air feed direct to the air intake you should be fine.

Try stuffing the blower hose full of rags to shut it up and disconnect the blower power; take her for good run at normal and hard revs, monitor the temperature if you like but I will bet you almost anything you will only notice less noise and smell.

Avagoodweekend......

PS: We run twin 30 HP VP's and have a dorade on deck with a 5 inch duct that runs down to the floor (Cool air flow at the bottom). The engines have bulk heads fore and aft so no fuel or engine smells at all, also very very quiet. Large well insulated hatch on deck for access and room to walk around the engine. If air was a problem I imagine it would be a real problem in a larger area with less turn over, but we have never had a heating problem, stepping down to the engines to turn off the batteries and fuel lines only minutes after shut down the area is fresh and not hot at all.

 

[Marsupial]

I use sails, I find its much much quieter, anyway on Yanmar installations the blower is used to get rid of excess heat which would otherwise compromise the efficiency of the engine. Its a physics thermodynamics thing, if your not worried about flywheel BHP then turn it off.

 

[TheBoatman]

I agree with the other posters on this one ~ it is unnecessary to use a bilge blower on a 30hp diesel engine if it has a reasonable supply of fresh air.

As suggested try disconnecting it and running the engine hard for an hour or two. I would bet you the only difference you notice is the reduced noise level from the blower.

Peter.

 

[Oldhand]

Reducing blower speed normally substantially reduces noise and this can be done by puting a series power resistor in the circuit. The resistor value depends on the resistance of the blower motor and how much you want to slow it by.