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Old 15-05-2016, 02:35   #1
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Engine Fan broke again

The electric fan for my port engine has broken again. The first time the bearing went and the only solution was to replace the fan. I have forgotten the brand for the fan but noticed it was rated for 200 hours only. A bit low since I already have 500 hours on each engine.

Obviously I can do the same again and put another of the same brand. Or has anyone on a Lagoon 400 had the same problem and put in a different brand of fan?

Thanks

Brian
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Old 15-05-2016, 06:56   #2
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Re: Engine Fan broke again

Don't wish to sound trite, but why do you need fans? I'm assuming that these are ventilation blowers for the engine compartments.

My non S2 model and all others I've seen don't have these fitted. Ventilation is fine via the large corregated air ducts. Two less things to break and consume power?
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Old 15-05-2016, 09:12   #3
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Re: Engine Fan broke again

Thanks for the heads up on that Tuskie.

I wonder why Lagoon decided on this additional gear if it is not needed? And even stranger why did they add a fan with a 200 hour duty cycle? As Alice said 'This is stranger and stranger'.

Brian
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Old 24-05-2016, 16:17   #4
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Re: Engine Fan broke again

We have a L450, the original equipment Osculati radial blower failed on the starboard engine after 1200 hours (bearing) These come from italy.
I had trouble sourcing from USA but found an identical footprint blower from Johnson Pump model AirV 3-280 Flange Mount - designed for continuous duty. Not sure what L400 uses, but it is worth hunting around.

See part of a quote below from a marine insurance company:

"...
In diesel-powered boats, safety is not the reason to have an engine room blower. Diesel fumes are not dangerous and are unlikely to burn. However, diesel engines need enormous amounts of air. If the engine is starved for air, its life may be shortened. Blowers are installed to bring air in either directly or indirectly when mounted as exhaust blowers. In both cases, the blowers increase the amount of air entering the engine room to feed the engine. ..."
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Old 24-05-2016, 16:53   #5
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Re: Engine Fan broke again

Our L450 includes Jabsco blowers (150 CFM Blower; Model 34739-0010; or the slightly larger model) that are readily available in most chandleries or a quick order. We haven't had to replace ours yet - 1000hrs on each engine but have replaced the same in our generator room. Brian, you may be able to retrofit these into your L400.
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Old 24-05-2016, 18:51   #6
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Re: Engine Fan broke again

[QUOTE=See part of a quote below from a marine insurance company:
"...
In diesel-powered boats, safety is not the reason to have an engine room blower. Diesel fumes are not dangerous and are unlikely to burn. However, diesel engines need enormous amounts of air. If the engine is starved for air, its life may be shortened. Blowers are installed to bring air in either directly or indirectly when mounted as exhaust blowers. In both cases, the blowers increase the amount of air entering the engine room to feed the engine. ..."[/QUOTE]

Sounds like a bit of arse covering or ignorance to me, how could restricting the intake of an engine shorten it's life?? Almost ALL gasoline engines have throttle plates and they seem to last.
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Old 24-05-2016, 19:51   #7
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Re: Engine Fan broke again

Quote:
Originally Posted by Bean Counter View Post
We have a L450, the original equipment Osculati radial blower failed on the starboard engine after 1200 hours (bearing) These come from italy.
I had trouble sourcing from USA but found an identical footprint blower from Johnson Pump model AirV 3-280 Flange Mount - designed for continuous duty. Not sure what L400 uses, but it is worth hunting around.

See part of a quote below from a marine insurance company:

"...
In diesel-powered boats, safety is not the reason to have an engine room blower. Diesel fumes are not dangerous and are unlikely to burn. However, diesel engines need enormous amounts of air. If the engine is starved for air, its life may be shortened. Blowers are installed to bring air in either directly or indirectly when mounted as exhaust blowers. In both cases, the blowers increase the amount of air entering the engine room to feed the engine. ..."
A centrifigal fan is not going to fix a flow restriction issue. This is a sales bs statement.

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Old 24-05-2016, 21:46   #8
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Re: Engine Fan broke again

Quote:
Originally Posted by leftbrainstuff View Post
A centrifigal fan is not going to fix a flow restriction issue. This is a sales bs statement.

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Probably not, but the statement is reasonable. Engine room blowers are not a safety requirement for diesel installations, and the volume of air required is large.

Assuming that Yanmar 40 hp diesels are fitted; 1.64 litre capacity (100 cubes for the yanks ).
So, at 2000 RPM air volume is 3,280 litres per minute. Nearly one third of a cubic metre. To use the venacular; that really sucks!

As previously noted, my Lagoon 400 and many others of the same model, function perfectly without engine room fans. In my experience, the chief reason that engine room fans are fitted to diesel powered vessels is to reduce engine bay temperature. Not so much for the comfort of the engine, but for other reasons such as the cooling of battery banks, watermaker installations etc. or to reduce heat transfer to deck or adjacent cabins.
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Old 24-05-2016, 22:48   #9
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Re: Engine Fan broke again

Quote:
Assuming that Yanmar 40 hp diesels are fitted; 1.64 litre capacity (100 cubes for the yanks ).
So, at 2000 RPM air volume is 3,280 litres per minute. Nearly one third of a cubic metre. To use the venacular; that really sucks!
I think that you are off by a factor of two in that calc. These are 4 stroke engines, so there is only one intake stroke every other revolution, and thus at 2K rpm it would inhale only 1640 lpm. Still a lot of air, but I bet that the vents are sized correctly to allow low pressure drop at those rates.

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Old 25-05-2016, 00:25   #10
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Re: Engine Fan broke again

In our (long sold) Lagoon 410 the fans were designed to suck air / fumes / heat from the engine compartment. Not to provide fresh air.

Maybe the 400 is different?
Our Mahe doesn't have engine blowers at all.
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Old 25-05-2016, 00:29   #11
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Re: Engine Fan broke again

Quote:
Originally Posted by Jim Cate View Post
I think that you are off by a factor of two in that calc. These are 4 stroke engines, so there is only one intake stroke every other revolution, and thus at 2K rpm it would inhale only 1640 lpm. Still a lot of air, but I bet that the vents are sized correctly to allow low pressure drop at those rates.

Jim
Yes Jim, you are correct again.

Thanks, and hope to see you in sunny Queensland this winter. Safe sailing.
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Old 27-05-2016, 04:14   #12
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Re: Engine Fan broke again

See this link on engine life and air requirements
The Life Expectancy of the Marine Engine - BoatSafe.com
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Old 27-05-2016, 10:45   #13
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Re: Engine Fan broke again

A friend of mine, former Mobil Oil lubrication engineer, recommends using aircraft 'ashless dispersant' oil for engines that run for long periods at constant RPM (aircraft and boats) to keep them from carboning up. He said that after he talked a rapid transit company into using it in their EMD locomotive engines, they doubled their lifespan. Just passing this along.
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Old 27-05-2016, 11:21   #14
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Re: Engine Fan broke again

Quote:
Originally Posted by Bean Counter View Post
"...
In diesel-powered boats, safety is not the reason to have an engine room blower. Diesel fumes are not dangerous and are unlikely to burn. However, diesel engines need enormous amounts of air. If the engine is starved for air, its life may be shortened. Blowers are installed to bring air in either directly or indirectly when mounted as exhaust blowers. In both cases, the blowers increase the amount of air entering the engine room to feed the engine. ..."

Something doesn't add up here. An exhaust blower in the engine room decreases the back pressure and tends to hurt the engine's air intake efficiency. In effect the exhaust blower "steals" air the engine wants.

Exhaust blowers really have only one purpose which is to lower the engine compartment temperature. This helps the alternator life span. It doesn't do much else. A Diesel engine doesn't much care how hot the air is.

If there is a blower forcing air into the compartment (not an exhaust blower) then that helps the air intake efficiency. But it requires very special design details because of the risks. One risk is if there is an exhaust leak the blower may force exhaust gasses into living spaces. Another risk is fire. The blower must be turned off automatically by any fire detection/suppression system. Otherwise a fire will be provided one essential element it needs to keep burning.
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Old 27-05-2016, 11:37   #15
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Re: Engine Fan broke again

Temperature of intake air affects how much oxygen is inhaled with each intake stroke. That's why my truck's diesel engine has an intercooler as well as a turbocharger.
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