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Old 25-06-2013, 09:13   #1
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ENGINE BREATHER SYSTEM .

My Perkins Prima M50 was supplied with a rain cap type strainer on the air inlet .My engine breather system was piped to this cap although the standpipe that it connects to is welded into the open hood . I have since made up a S/S intake pipe onto which l have mounted a proper aircleaner . I would like to weld a standpipe on the intake pipe to connect the breather system to , but my concern is will the vacuum created by the engine cause a problem with the breather system .
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Old 25-06-2013, 09:36   #2
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Re: ENGINE BREATHER SYSTEM .

I did something like this to our 107. Added an air filter and plumbed in the breather downstream of the filter. It did suck in crankcase vapor and oil use increased. Ended up plumbing the breather tube directly into the air filter itself. This seems to have worked.
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Old 25-06-2013, 09:53   #3
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Re: ENGINE BREATHER SYSTEM .

You really need to put a PCV valve http://en.wikipedia.org/wiki/Crankca...ilation_system
inline to prevent the engine from running away. Not to say it will ever happen without it, but if for some reason the blow by contains more oil than usual and there is nothing metering the suction on the crankcase then the engine has just found it's new fuel source.
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Old 25-06-2013, 09:59   #4
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Re: ENGINE BREATHER SYSTEM .

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Originally Posted by Sailmonkey View Post
You really need to put a PCV valve http://en.wikipedia.org/wiki/Crankca...ilation_system
inline to prevent the engine from running away. Not to say it will ever happen without it, but if for some reason the blow by contains more oil than usual and there is nothing metering the suction on the crankcase then the engine has just found it's new fuel source.
That would be a backwards PCV valve?
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Old 25-06-2013, 10:08   #5
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Re: ENGINE BREATHER SYSTEM .

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That would be a backwards PCV valve?
blah....your correct. Either way, the volume of vacuum needs to be controlled to prevent the above mentioned problems.
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Old 25-06-2013, 12:43   #6
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Re: ENGINE BREATHER SYSTEM .

Many thanks guys for your replies . I have read the link you posted on PCV valves and now understand what their function is although you mention it should be mounted backwards ? Please explain how this would work . Secondly , you mentioned that you fitted the pipe into the aircleaner housing . Would that not be the same as connecting it into the intake pipe or did you connect the pipe ahead of the element . Apologies for all the questions but l am about to cross the South Atlantic and want to make sure l get this right .
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Old 25-06-2013, 14:23   #7
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Re: ENGINE BREATHER SYSTEM .

I think the pcv valve idea is pretty much for a gas engine. It prevents a back fire from getting into the crank case. Not something you need to worry about. Sorry for being ironic. The reason for plumbing the vent line into the air filter is to get to as far from the engine as possible so the air pressure is as close to ambient as possible. Anything down stream of the filter is lower pressure and will suck in oil vapor. In my orginal 107 set-up, the vent was outside the inlet screen but the suction drew the vapor into the engine. It would be hard to have the same thing with an air filter, I think it would make a mess. I used a K&N filter that had plastic ends so I just plumbed the breather line into the inside of the filter. There is not much vacuum inside the filter because of the large area of the filter media.
I think the concern for a runaway engine is not anymore of a problem than it would be with the orignal air inlet.
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Old 26-06-2013, 05:27   #8
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Re: ENGINE BREATHER SYSTEM .

The more l think about it , the more l dislike the idea of plumbing the breather into the air intake pipe . As the restriction builds when the aircleaner gets dirty , the vacuum increases on the breather system increasing the amount of oil vapour being drawn into the air intake . Guy , what about leading the breather pipe vertically so that the oil does not fill the pipe causing a pressure build up in the crankcase , then fitting a course strainer onto the end and keeping the system separate from the aircleaner . Leading the pipe vertically would allow the oil that collects on the walls of the pipe to drain back into the crankcase .
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Old 26-06-2013, 09:12   #9
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Re: ENGINE BREATHER SYSTEM .

What you describe is an air oil seperator, kind of. The only kind I know of, requires an oil return line, not using the breather line itself
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Old 26-06-2013, 09:25   #10
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Re: ENGINE BREATHER SYSTEM .

here's the commercial solution. it has a vacuum regulator inline to prevent the problems I described earlier.

Walker Engineering - Product Detail
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Old 26-06-2013, 10:43   #11
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Re: ENGINE BREATHER SYSTEM .

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Originally Posted by Sailmonkey View Post
here's the commercial solution. it has a vacuum regulator inline to prevent the problems I described earlier.

Walker Engineering - Product Detail
Wow , what a complicated set up for such a simple task and $500 no less.
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Old 01-07-2013, 16:14   #12
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Re: ENGINE BREATHER SYSTEM .

Sheesh you guys get real complicated over simple things. Let the crank case breather vent into the intake, that's what all modern diesels do for .... sake, if you fit a sufficient size paper element air filter upstream(recommended) it will cut down engine intake noise by 25% or more. The crankcase breather vents in there to cut down on emissions, t'aint complicated at all.
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Old 07-07-2013, 07:59   #13
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Re: ENGINE BREATHER SYSTEM .

interesting posts - I want to simply vent the breather outside the boat and dump the oil vapour, as i understand that a return line to the air intake would add sludgy/carbony blowby gases into the intake.
but i am queasy about putting a hose 'out of the window', or worse underwater, since there's a risk of water coming back into the engine oil! {plus air pollution to the crew} so -
1 does anyone know of a oneway valve to fit inline?
2 does anyone know of an oil catcher/separator/filter housing ?
3 where should i mount the outboard end of the hose and the above kit?
4 also the sump breather outlet on our ford dorset diesel is a plain aperture of about 1in diameter. what sort of fitting would serve to plumb the hose in ? i assume a THF type would do, but obviously i don't have access to the far side in side the sump!

thanks

John
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Old 08-07-2013, 20:22   #14
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Re: ENGINE BREATHER SYSTEM .

Why would you want to complicate a simple system and why would you want and air filter your boat that dirty.HA! My engine dripped oil from the straight breather tube so I put a 90% hose that pointed up on the end to cup the oil so to speak, it would then drain back to the engine. a pcv systemis a check valve that prevents back fires into the crankcase and utilizes vacuum from the intake which a diesel does not have
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Old 08-07-2013, 23:28   #15
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Re: ENGINE BREATHER SYSTEM .

Quote:
Originally Posted by ALLAN WARD View Post
My Perkins Prima M50 was supplied with a rain cap type strainer on the air inlet .My engine breather system was piped to this cap although the standpipe that it connects to is welded into the open hood . I have since made up a S/S intake pipe onto which l have mounted a proper aircleaner . I would like to weld a standpipe on the intake pipe to connect the breather system to , but my concern is will the vacuum created by the engine cause a problem with the breather system .
Hi Allan,

because I have the same engine as you do I wanted to ask a few questions:

1) What is wrong with the original setup? Why should it need to be changed? (sorry I don't have enough experience about this subject)

2) I only have a metal screen/mesh in the metal air cleaner "Cover", no paper filter, no foam element - do you have the same or am I missing something? Neither the owner's manual nor the Perkins Part Book are clear about this.

Thanks,
Erik
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