Engine blower motor

[JohnB40]

Hi
Have a Beneteau 40, 4JH4AE Yanmar.
There is a Plastimo air blower on the transom to extract hot air from engine compartment. Stopped working. Took apart and see the small 4 amp 12V DC motor is labelled Von Weise, made in Canada, 2807-506-006. Motor is fried. Rather than pay about $300 for blower replacement I would like to replace just motor which seems to cost about US$50 ... if you can find it. I have found a motor that has same measurements (Kysor 2807-506-032) but that is apparently not quite right as is two speed ... that one is US$50.
Has anyone any idea where I can find this motor ... I've searched the web but I'm not very good at that ... sort of a dinosaur!!!
Cheers
JohnB40

[jamhass]

John:

No idea on motor sources for you, but offer a couple of thoughts:

1. Can you relatively easily adapt the alternate motor to the housing? might not be worth the cost difference if the mods needed are excessive or difficult.

2. Your post notes the blower exhausts the engine compartment. I might suggest you reverse the blower AND focus the airflow on the alternator. This a) helps cool the alternator better and b) keeps the blower itself cooler which will extend its life.

[Zai]

I am using something like one of these and it seems to move a lot of air.
About 30 dollars.

https://www.defender.com/product.jsp...138&id=4009999

[a64pilot]

I have never seen a $300 blower.
You have a link to it? I’m curious as to what you have

[Unity]

Originally Posted by jamhass

I might suggest you reverse the blower AND focus the airflow on the alternator. This a) helps cool the alternator better and b) keeps the blower itself cooler which will extend its life.

Wouldn’t blowing air from outside into engine compartment (instead of the normal pull air from inside to out) result in both pushing hot air through various leaks in the compartment into your living space and also increase the risk of carbon monoxide in your living spaces?

[Uncle Bob]

Originally Posted by Unity

Wouldn’t blowing air from outside into engine compartment (instead of the normal pull air from inside to out) result in both pushing hot air through various leaks in the compartment into your living space and also increase the risk of carbon monoxide in your living spaces?

And just where do you think the air that has been sucked out came from??

[a64pilot]

Unity is correct, you want the engine compartment to be a negative pressure area, meaning of course that any fumes, smoke, smells, or just heat goes out the blower hose or out through the engine intake.
If you over pressurize the engine room, all that may leak out into the Salon.

[Unity]

Well, in theory you should have a minimum of an inlet hose from outside (no blower) and an outlet hose (with blower). Air blowing out causes a vacuum in the engine compartment and pulls air in, some from outside and some from inside (usually less). But more importantly, fumes are being sucked out rather than being pushed in. Very low risk of fumes leaking into your living spaces thanks to that vacuum.

In the opposite mode, pushing air from the outside creates a space in the engine compartment that is now pressurized and the air is pushed out to escape, some out the exhaust (non-blower in this case) hose and some into your living spaces.

Also consider an engine room fire. Same problem, but now smoke is being pushed through cracks rather than being pulled out.

Personally, I would never allow my engine room to become pressurized but rather always held in a vacuum.

[Zai]

I don't think it is a good idea to have either overpressure or under pressure.
The engine needs a good air supply in order to run right.

In my installation I have a blower, blowing air from high over the engine to an overboard vent and an intake hose low right near the engine supplying the engine with cool air also from an overboard vent.

[Nicholson58]

Originally Posted by Unity

Wouldn’t blowing air from outside into engine compartment (instead of the normal pull air from inside to out) result in both pushing hot air through various leaks in the compartment into your living space and also increase the risk of carbon monoxide in your living spaces?

Absolutely correct. Th air must be sucked from the engine space so there is a slight negative pressure. If the engine room is positive pressure the stink and any pollutants will be in your living space.

I would be looking for a total replacement blower. Many options out there.

[Jim Cate]

Seems to me that the engine itself will keep the engine compartment at negative pressure relative to the cabin. It moves more air than most blowers that are fitted to small yacht engines. Additional blowers can mean a larger pressure differential, but dunno how much difference that makes in a practical sense.

Jim

[Dockhead]

Originally Posted by a64pilot

I have never seen a $300 blower.
You have a link to it? I’m curious as to what you have

Continuous duty engine room blowers do cost around that much.
https://www.jabscoshop.com/marine/bl...24-volt-dc.htm

I replaced one this summer at 4000 hours. Worth every penny IMHO.

[Dockhead]

Originally Posted by Jim Cate

Seems to me that the engine itself will keep the engine compartment at negative pressure relative to the cabin. It moves more air than most blowers that are fitted to small yacht engines. Additional blowers can mean a larger pressure differential, but dunno how much difference that makes in a practical sense.

Jim

7 m3 per minute blower vs 3 m3 per minute a 2000cc diesel at 3000 RPM? Or less than 1 m3 per minute at idle?

If you want to choke on fumes, just reverse your blower.

That being said, however, the main engine on my boat keeps the ER reasonably cool in cool weather, without the blower going. A couple m3 per minute is a fair bit of air.

[Jim Cate]

7 m3 per minute blower vs 3 m3 per minute a 2000cc diesel at 3000 RPM

DH, I doubt that many of the blowers fitted to normal yachts actually move anything like 7m^3 /min as fitted. The advert numbers are mostly at zero head, and that ain't reality. The engine will move just what it needs to fill the cylinders, pretty uch regardless of pressure drop en route.

At any rate, even one m^3 per min is enough to keep the pressure differential in the right direction. Dunno how much benefit one gets from bigger diffs, anyway!

Jim

[Dockhead]

Originally Posted by Jim Cate

DH, I doubt that many of the blowers fitted to normal yachts actually move anything like 7m^3 /min as fitted. The advert numbers are mostly at zero head, and that ain't reality. The engine will move just what it needs to fill the cylinders, pretty uch regardless of pressure drop en route.

At any rate, even one m^3 per min is enough to keep the pressure differential in the right direction. Dunno how much benefit one gets from bigger diffs, anyway!

Jim

Well, my particular blower (link above), does move 7 m3, nominally.


A 2000cc diesel moves 1 m3 per minute per 1000 RPM -- also nominally.



Both will realistically move less than nominal, and the difference will probably be roughly similar (intake and exhaust system resistance vs blower ducting resistance).




If your point is that the diesel alone will be enough to keep the pressure differential at an adequate level -- I agree with you.


But engine room blowers aren't for that -- they are for pulling cool air through the ER to keep the temps down and give the engine cool air to breathe. And alternators and other gear in there. They suck rather than blowing so that the blower doesn't counteract the engine's sucking power and create overpressure in the ER.



Therefore, it was very bad advice to advise the OP to reverse his blower.