Outboard Air filtration

[Blaster Bretty]

Motor played up a bit yesterday, turns out the fuel plug was not connected properly, Put a whole new batch of fuel in and cleaned the plug and she went great today!
While investigating the motor to see what was wrong I took the airbox apart to have a looksie in the carbie's and to my surprise there was no air filter at all inside the airbox, no air filter in the cowling inlet either. My question is shouldnt there be an air filter of some sort, I had a look at BCF while I was there and they didnt have anything ,only the run of the mill fuel + oil filter's but nothing for the air intake!
Any thought's on this bloke's!
for what its worth I brushed down all the padding / foam surrounding the inside of the cowling and blew it clean with the air hose ,as some of it was flaking off, only hope not too much has gone into the airbox already! but she didnt miss a beat today with a good 30 mins running time!

Bretty

[BM]

Theres no dust on the water Bretty, hence no requirement for a filter. Its been that way forever.

Cheers

[Noelm]

yep, it is only to stop water being sucked into the Motor, if you look at how it is designed, it would be almost impossible for water to get in if you had a "dunking" ,but, not moisture laden air which can cause drama sometimes.

[BM]

Bretty, the best thing to do with that insulation when it becomes perished is to remove it completely or else the engine WILL inhale it and it tends to get stuck in the reeds. You can put new stuff in if you chose to or simply leave it out. Won't effect the engine noise much, although...... these days with people in some cases buying engines based upon how quiet they are (I'll never work that one out!) some may take issue with not replacing the foam.

cheers

[Blaster Bretty]

yeah thanks for that guy's, I must admit I was surprised to see nothing though! Ive tinkered with cars + motorbike's for years but not boat motor's, this is my first one,
thank's again

Bretty

[finga]

What about the dust that settles in there after towing the boat along a dusty road??

[Chimo]

Hi Finga

I doubt that it would be an issue unless the boat motor was operating to suck air in and thats not very likely except at Xmas with a dufus and his new toy!:-/

Cheers
Chimo

PS I saw your US fob watch operating without its cover sort of in bits today. Someone has been inside the cover with a screwdiver and a pocket knife it would seem:P At least it was sort of running but it looks like it has to be pulled to bits again to true up the balance wheel thingy etc .


Pity its not like a bike wheel with spokes and you could hit it with a spoke key. C says he has a machine to true it up;D

[Blaster Bretty]

What about the dust that settles in there after towing the boat along a dusty road??
I also rekon that if you were out wide and on your way back and it started to rain or even that constant drizzle, wouldnt that sort of get sucked in and cause trouble??

Bretty

[Chimo]

Bretty

Think about cats and the salty mist they throw, now that kills motors eventually.

On the other hand I used to add about 5ml of water per km thru the air intake on my V8 and all that did was allow me to advance the spark another 6 degrees to about 12 degrees total and with a few other mods got me from 18 mpg to about 30 mpg. When we rebuilt it after years there was very little carbon and what there was there came off easy.

Moral. IMHO a little unsalted water is great thru a motor; just keep the salt out of it.

Cheers
Chimo

[cormorant]

Not real sure salt water is any worse than fresh water. Have seen same damage on lake boats in the USA ( just takes a bit longer). Especially with 2 strokes where the air goes through the crancase and bearings it can cause rust and corrosion if the motor isn't run regularly and oil coating kept on. Good oils make a huge difference in teh coating they leave on boare and crankcase. 4strakes have an advantage but still get rusty bores if not actuallt started regularly.

A smart manufacturer would design it so all valves are closed on stop as without air contact less ocrrosion happens. It will happen with electronic valves.

Misting isn't only cats and some are better than others. A lot of deaths that were said were misting were dunkings , backing down on fish, not turning over the motor once a week, dunking when launching. This happened with offshore monnos as well. With longer shafts things have movesd on a lot and also cowl design helps..

[Blaster Bretty]

Bretty

Think about cats and the salty mist they throw, now that kills motors eventually.

On the other hand I used to add about 5ml of water per km thru the air intake on my V8 and all that did was allow me to advance the spark another 6 degrees to about 12 degrees total and with a few other mods got me from 18 mpg to about 30 mpg. When we rebuilt it after years there was very little carbon and what there was there came off easy.

Moral. IMHO a little unsalted water is great thru a motor; just keep the salt out of it.

Cheers
Chimo
Hmmm adding water to the air flow...doe's this help cool the air a bit for a better combustion, ive heard of high powered turbo's and the like doing this and then they also spray water on the intercooler as well to keep the intake temp down...Hmmmm very interesting point of view there chimo!!
I do suppose that if it were of great concern we would be hearing a lot about donk's dying from water vapor in the air flow but it doe's seem to be under control!

Bretty

[BM]

I also rekon that if you were out wide and on your way back and it started to rain or even that constant drizzle, wouldnt that sort of get sucked in and cause trouble??

Bretty

Nope. The air intake into the cowl is a water lock. Dense, fine misting could and does make its way in (as mentioned by someone else, cats suffer from this mist destroying the engine if they don't have snorkels fitted).

If it were a problem in the mainstream boating then the manufacturers would have rectified it many years ago but they haven't altered them so there is evidence enough that its not typically an issue.

Cheers

[ozscott]

I used to have a hot holden 6 in a HQ that I water "injected". I just used a tap and it was adjustable to fine increments and it would simply suck it in through the carb venturi style....nice clean plugs, clean pistons and valves, more power and better economy...nice

[BM]

Thats a bit different though ozscott as its injected into the upper cylinder.

Water ingested into an outboard enters via the carbs, past the reed valves, sloshes around past the crank and bearings and then up to the upper cylinder.

That water going past the crank bearings will destroy the crank journal hardening and the bearings.

cheers