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Diesel fumes from breather cap

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fatjohnz View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fatjohnz Quote  Post ReplyReply Direct Link To This Post Posted: 18 July 2017 at 9:46am
Good info here gentlemen. I was pulling my hair out trying to figure out where the fumes were coming from and poof(!), a solution in the forum. Thanks, John
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fatjohnz View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fatjohnz Quote  Post ReplyReply Direct Link To This Post Posted: 25 July 2017 at 12:59pm
I'm surprised by the amount of air flowing from the vent tube now that it's captured in a hose. Does back pressure on this vent pose a problem for the engine operation? js

Edited by fatjohnz - 25 July 2017 at 1:01pm
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bal149 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bal149 Quote  Post ReplyReply Direct Link To This Post Posted: 01 August 2017 at 8:39pm
i agree , nice work. The drawback is that you must now check your air filter more often as that oil mist will clog it up. Running the lines into the filter housing downstream from the filter would avoid this, but should the Buhk take a big gulp of oil that has pooled in the bottom of the housing the con rod will suffer (hydraulic lock). The reed is there to generate negative pressure in the crankcase so that the seals are not blown out. Pollution controls on cars plumbed this back into the air intake as you have done -PCV valve. They do not heel like a laser so there are no big discharges that could cause problems. Cars that sustain high G forces pump their oil into a tank to avoid this (Dry Sump).
This was on a lot of classic motorcycles in the past but now internal baffles prevent large losses of lubricants. You can't make a silk blanket from a sow's ear but you have greatly improved what is at best a very old design.Big smile
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Mad Max View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mad Max Quote  Post ReplyReply Direct Link To This Post Posted: 02 August 2017 at 6:30am
I've been thinking about adding a catch can to Mad Max so solve (avoid) this very problem.  People have been adding these to cars to cut down on repairs to direct injection vehicles where the intake valve is being fouled after thousands of miles.  Here is an article explaining the problem with autos. 

http://tinyurl.com/ydf8slph

I'm thinking a metal can with screw on lid containing heavy steel wool acting as the separator would eliminate the problem.  Mounted in a convenient location for easy access, simply duct the breather hose in and out before entering the air intake.
Looking for input.
Dick #122
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Bill Layton View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bill Layton Quote  Post ReplyReply Direct Link To This Post Posted: 02 August 2017 at 7:08am
The air filter in the snorkel is actually only a wire mesh screen so oil won't clog it. I keep my snorkel vertical. If your worried that your collecting too much oil in it you could drill a hole in the bottom outside of the wire screen and this would allow it to drain in to a catch can.. or even on to a rag. I haven't collected any oil in my snorkel in the 2 years it's been installed. If you do not use your engine with the boat heeled it won't be an issue. And if you do you should be wise enough to check it out occasionally. This device isn't meant to compensate for using the engine when heeled. It's only to keep the crankcase fumes separate from the air you breathe down below.

Catch cans on cars are meant to drain automatically back into the engine. To do this on this engine it would have to be mounted above the oil filler neck of which there isn't much space between the cockpit floor and the top of it. 
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frfletch View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote frfletch Quote  Post ReplyReply Direct Link To This Post Posted: 02 August 2017 at 10:36am
I have been running with this re-breather for over 3 years now and we race 12 months per year plus do some cruising in the summer. I haven't had any problems to date. My observation is that because my tube mounts vertically to the top of the fill cap, the oil fumes condense as they rise and cool coming out of the cap and into the hose. Then, any condensed oil probably runs back down into the engine via the same route it came out of when the engine is not running. No idea how it gets past the reed valve, however I can see some oil residual in the clear hose up to about 100mm above the attachment to the cap, but none beyond that, so I'm guessing that is what happens. I think it never makes it to the air filter. I took my cap off the other day and neither was there any accumulation of oil between the top of the cap and my re-breather cap. If one makes one of these gismos, I can advise that if you use that clear reinforces plastic hose that is on Voila, it may look upon installation that it stands up nicely to bridge between the oil fill cap and the air filter. However when the engine compartment heats up, the plastic goes temporarily soft and will sag onto the flywheel. I support mine by suspending it from the bottom of the cockpit sole, or the top of the engine compartment.

Finally, I am not afraid of engine damage at this point and the arrangement keeps my boat smelling fresh when running and also keeps my engine compartment much cleaner that having the oil fumes condense all over the place at large after escaping the original oil cap into the atmosphere.
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fatjohnz View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fatjohnz Quote  Post ReplyReply Direct Link To This Post Posted: 18 September 2017 at 6:44pm
Hi Frank, Nice work! You have a PM with my address. John
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Winner Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2017 at 8:11pm
I'll be doing this modification as a winter project.  Two questions:

1) The pictures that Frank posted a few years ago no longer seem to be active.  Frank are you able to repost them or email them to me?

2) I removed my oil filler cap and air intake to bring home and noticed that the wire mesh of my air intake is pretty sooty.  Can I just clean it with diesel fuel or is something else better?
Chris
Eclipse #240
Thunder Bay, ON
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Bill Layton View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bill Layton Quote  Post ReplyReply Direct Link To This Post Posted: 23 October 2017 at 6:49am
You can wash the air cleaner screen in just about anything. From Lacquer thinner to Kerosene, even paint thinner works.
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Mad Max View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mad Max Quote  Post ReplyReply Direct Link To This Post Posted: 23 October 2017 at 9:08pm
Unable to view pictures, what am I missing?
Dick #122
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Winner Quote  Post ReplyReply Direct Link To This Post Posted: 10 March 2018 at 4:25pm
I'm shamelessly bumping this.  Frank by chance do you still have those pictures of your setup for the rebreather cap?  The ones you posted a few years back have a broken link now.
Chris
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Post Options Post Options   Thanks (0) Thanks(0)   Quote frfletch Quote  Post ReplyReply Direct Link To This Post Posted: 10 March 2018 at 6:51pm
Hi Chris,

Sorry. I made this item up for you and then moved my shop. I will find it and send it. Please send me your mailing address.

Frank
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Post Options Post Options   Thanks (0) Thanks(0)   Quote John Mills Quote  Post ReplyReply Direct Link To This Post Posted: 29 April 2018 at 7:14am
Did this upgrade , easy to do . will let you know if it worked . I note that I was surprised that the crankcase is sealed and the reed valve seems to be there to let presure out but there is no "intake" so the air does not seem to flow through . I guess you are just catching the blowby ? 
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