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Author Topic: routing crankcase breather back to intake?  (Read 5455 times)

mjn

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routing crankcase breather back to intake?
« on: January 11, 2007, 12:20:11 AM »
In an attempt to cut down on the oily film all over my engine, I am considering adding a tube to route the crankcase breather back to the intake.

Is this a good idea?  I'm concerned that the oily vapors could cause a runaway.  Is there something I can do to trap the oil?
Changfa 195 7.5 kw ST.  WVO conversion http://martin.nile.googlepages.com/
Metro 6/1 DI Listeroid. Pumping water for fire control.
1933 Stover CT-1 hit and miss
1936 Farmall F-12 -- unrestored, still used to mow the field

rmchambers

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Re: routing crankcase breather back to intake?
« Reply #1 on: January 11, 2007, 12:45:18 AM »
It's a good idea to be wary of a runaway.  What you need to do is get some sort of air/oil separator device.  They are common on airplane engines of people who hate greasy bellies.  I think you could make one easily enough, you'd need a cylinder with a fixture on each end and then some material inside the cylinder for the oil vapor to condense on and turn into drops that would eventually run back down the intake port into the sump.  I'm thinking something like one of those pot scrubber deals (stainless one) might work pretty well.

I'd also try and use a clear tube at least on the top of the device that goes into the intake area so you can see at a glance if anything is making it past the separator.

I'd also plumb the return into the outside of the air filter area not the intake tube.  Doug I believe told the story of a gas generator that had the breather plumbed into the intake behind the filter - once the filter clogs a bit the engine sucks all the oil out of the sump and you seize (or in the diesel's case runaway and then seize).

Robert

europachris

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Re: routing crankcase breather back to intake?
« Reply #2 on: January 11, 2007, 01:26:24 AM »
In an attempt to cut down on the oily film all over my engine, I am considering adding a tube to route the crankcase breather back to the intake.

Is this a good idea?  I'm concerned that the oily vapors could cause a runaway.  Is there something I can do to trap the oil?


How much oil are you getting out of the breather?  I've not even seen so much as a wet spot on the end of R185, and it does indeed breathe.  I believe there is a reed valve arrangement in there, also, as I can hear it 'squeak' when I crank the engine slowly.

Granted, I've only got maybe 10 hours on my setup (backup only), so I'm sure it's not a real fair comparison....

Chris

wrightkiller

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mjn

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Re: routing crankcase breather back to intake?
« Reply #4 on: January 12, 2007, 07:16:28 PM »
How much oil are you getting out of the breather?  I've not even seen so much as a wet spot on the end of R185, and it does indeed breathe.  I believe there is a reed valve arrangement in there, also, as I can hear it 'squeak' when I crank the engine slowly.
...
There is a light film of oil in the vicinity of the breather output.  In my case, the breather output is directly onto the governer lever and spring.  The oil makes a wonderful "dust catcher" which gets onto my hands whenever I am working in that area.

At low power, I don't see anything coming out of the breather.  With a  heavy load, I can see a light fog coming out of the breather. 

Changfa 195 7.5 kw ST.  WVO conversion http://martin.nile.googlepages.com/
Metro 6/1 DI Listeroid. Pumping water for fire control.
1933 Stover CT-1 hit and miss
1936 Farmall F-12 -- unrestored, still used to mow the field

europachris

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Re: routing crankcase breather back to intake?
« Reply #5 on: January 12, 2007, 09:22:12 PM »
There is a light film of oil in the vicinity of the breather output.  In my case, the breather output is directly onto the governer lever and spring.  The oil makes a wonderful "dust catcher" which gets onto my hands whenever I am working in that area.


Interesting.  The breather on my R185 is on the crankcase cover at the 'end' of the engine.

You should have no problems running that back to the intake.  Shoot, both our VW Jetta TDI wagon and Jeep Liberty CRD run the crankcase vent back to the intake.  Both pump a fair amount of oil through them.  Combine that with the soot from the wonderful EGR systems and you have a recipie for serious intake clogging..... >:(

chris