Originally Posted by romel
The engine blower on my Jeaneau Sun Odyssey has a thermostat that runs on one of the power lines. (Not sure if its the positive or the negative now) So the blower only comes on when the engine room temperature rises above the preset value of the thermostat (usually after 20 minutes or so of motoring) and will stay on till the temp comes back down. The blower runs independently of the engine circuit so that it will stay on even with ignition key turned off. I prefer it this way as it helps cool the boat
down when I get to an anchorage. Normally the blower will stay on 15 to 20 minutes and cycles off /on several times after the engine is turned off as the engine radiates heat. Understandably ambient temperature makes a lot of difference. This difference is easy to notice in winter
as the fan will take longer to start and is quicker to turn off.
In my experience the fans (even the name brands) do not last longer then 2 to 3 seasons. So the last time I replaced with a much cheaper unbranded one which has been there for 2 seasons now. In that time I have never had a problem with the thermostat. I check the thermostat by blowing a hot hairdryer on it to simulate a hot engine room. Do make sure there are no fuel
fumes in the engine compartment before starting a hair dryer.
If you supply the motor
with DC directly from a battery
and it runs OK then start following your power supply lines.
Hope this helps
That was one of the modifications I installed onto my boat.
My boat has gasoline engines and the factory fitted a pair of SHURflo 4" 220 cfm yellowTAIL blowers
to extract possible gasoline fumes. The intake for these blowers is down low in the bottom of the engine room.
Operation of these blowers has minimal effect on the internal engine room temperature. That is because gas fumes are heavier than air, so the intake must be low, but warm air rises, so sucking from low is not optimum.
On my boat the engine room is encased in thick insulation
and weatherstripping. This contains the heat and noise
from the engines.
The problem with this configuration when operating in a warm / hot climate is that the closed engine room temperatures will climb when the engines are shut down, such as stopping for an on-hook lunch break.
With my gasoline engines under these conditions I would suffer vapor lock and would be unable to restart my engines. I tried the Factory Service
Bulletin tips, but the last step was always to decrease the engine room temperature.
The only effective solution without boat modification would be to open the engine compartment when stopping, but that didn't work
on-hook, because guests would want to sit at that area, using those seats and table.
My solution was to add an additional pair of these 220 cfm blowers to suck engine room air out to exterior exhaust
under thermostatic control. The NTC sensor
is placed near the exhaust elbow
, as is the up-high air intake. The air intake is very close to the fuel rail.
This is a perfect solution!
Now when I drop anchor
I hear my blowers kicking on and off automatically to maintain the engine room setpoint temperature that I currently selected at 45°C.
A 12VDC thermal controller was purchased off eBay and was installed per the ABYC standards.
It has been working great for years.