blowers for diesel engine

[Mat-C]

I know that an engineroom blower is mandatory for a petrol engine installation, but is it a requirement for a diesel?

[whitepointer23]

not for diesel

[Stumble]

They are still a good idea though. Nothing worse than changing a filter in a seaway with the smell of diesel fuel wafting off of a warm engine... Turning on a good blower can help vent the smell, and reduce the vapor intrusion into the hull. They can also help reduce humidity inside the boat that helps to prevent mold.

[FAST FRED]

A blower might not be required but good ventilation is.

Good , is when the engine compartment is 20- max 30 deg above outside air temps.

Not that easy to do without LARGE vents to feed the engine space.

FF

[michael pierzga]

The blower is used to evacuate waste heat from the engine compartment.....very important for machine room longevity. Use an AC electrified blower via inverter for max reliability. The largest capacity that you can fit. Set the blower on a timer relay....so that the blower runs 30 minutes past engine shut down. The most damaging heat buildup develops after engine shut down.

Filter the blower intake with standard household heating system filters to keep your machine room clean.

[Ike]

Diesel use lots of air. Give it to them. Install a blower. Too many engine rooms starve the engines of air.

[Landlubber]

...yep, like they said, feed it plenty of fresh air, however you decide to do so.

[Willallison]

Mat,
From memory, you have a 30-something foot diesel engined sports cruiser, so I assume you are referring to one of the small in line, pre-start blowers like you see on (hopefully all) petrol engined craft.
As the others have said, it is not a requirement to fit one of these to a diesel engined boat.
However, diesels like to be fed with 3 things - clean fuel, clean oil, and cool air. Engine manufacturers specify both the required air intake cross-sectional area and the maximum increase in engineroom temperature relative to the outside air. In my experience, few small production craft comply with the first and probably not that many comply with the 2nd.
If yours doesn't, then a continuous duty blower is definitely a worthwhile investment.

[Mat-C]

Thanks everyone.
Yes, I have a 30ft 'sportscruiser' that has a single diesel sterndrive.
I was really only asking about the pre-start blowers, but this give food for thought... I might go check the engineroom temperatures...
thanks again

[michael pierzga]

Purchase a cheap Hi Lo thermometer. You will be surprised at the heat buildup...particularly the overheat spike that occures after engine shut down.. That heat spike prematurely ages everything in the machine room.

[Stumble]

I had never really thought of this, just assuming than the manufacturers had installed adequate ventilation. A quick check with my cooking probe thermometer proved that my deltaT was significantly above the recommended 30degrees on two of my engines (port side and generator). Looks like I will have yet another thing to take care of on my next haul out.

As an aside, does anyone know of a quiet ventilation fan? Mine sounds like a jet engine when running.

[michael pierzga]

Youre correct Stumble. Both Naval Architects and builders fail to supply adequate space and ventilation for machinery. First class machine room ventilation systems are expensive and space consuming to build. Obviously both Input and exhaust air ducting must be installed to function dry in heavy weather and be quite.

When installing your system be particularly careful with the intake side. Large diameter, straight run ductwork to avoid JET ENGINE noise, cushy mountings on the blower, flood proof with the ability to close off and choke the air supply in the advent of fire in the machinery room. I find standard AC blowers from a typical household heating system to be cost effective and long lasting.

For a small craft a good compromise is a two intake blower systems. Smaller intake ducting and blowers are eaasier to retrofit when you use a two blower layout and most importantly one blower can be shut down to conserve stored DC battery power when evacuating waste heat after powerplant shut down.

[CDK]

Originally Posted by Stumble

I had never really thought of this, just assuming than the manufacturers had installed adequate ventilation. A quick check with my cooking probe thermometer proved that my deltaT was significantly above the recommended 30degrees on two of my engines (port side and generator). Looks like I will have yet another thing to take care of on my next haul out.

As an aside, does anyone know of a quiet ventilation fan? Mine sounds like a jet engine when running.

Wire the blower in series with a "Klixon" thermostat so it only runs when necessary. That is a coin size device you can screw (or glue) on a known hotspot. It switches at a fixed threshold and is available in 10 degree steps for approx. $ 2.

For quick temperature measurements I recommend a Chinese $ 25 infrared laser thermometer.