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Old 06-25-2016, 10:29 AM   #1
Bus Geek
Join Date: May 2009
Location: Columbus Ohio
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Year: 1991
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Chassis: International 3800
Engine: DTA360 / MT643
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IHC DT engine no blow by?

as I keep workign on and learnign my way around a diesel engine.. I had been reading that all diesel engines need to "breathe" and they do so by way of a breather tube or some call a Blow-by tube.. .

my neighbor says thats how the crankcase pressure is relieved ion mechanical engines like mine so that it doesnrt blow all of the seals out of the engine..

a couple people told me its normal to see "smoke" coming out of this tube and all diesels do it..

I located my Breather tube.. pointed at the ground on the side of the engine.... i started the engine and there is nothing coming out of that tube whatsoever... no air no smoke no steam no notrhing coming out of that pipe..

is that normal or is my pipe likely clogged up?

I do have a slight oil seep (I see wetness around the rear main and occasionally a couple drops of oil on the ground but my oil level stays high and my exhaust doesnt smoke)...

do your guys diesels smoke from this breather pipe?

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Old 06-25-2016, 12:38 PM   #2
Bus Crazy
Join Date: May 2016
Location: Georgia
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Chassis: IH
Engine: T444E
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You may not see anything at all at idle. Might see a little something at high idle. Bet you'd see something at 1500+ RPM's under a load, like when it's being driven. Many newer engines may not have this breather tube open toward the ground, it would be routed to the intake system and burned.
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Old 06-25-2016, 04:15 PM   #3
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Location: Richmond Virginia
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Engine: 366 Big block Chevy! :) w/ Stick shift
I only notice crankcase smoke or fog after a motor has been run for a stint. Then that will show up.
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Old 06-25-2016, 07:16 PM   #4
Bus Crazy
Join Date: Nov 2011
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Chassis: B3800 Short bus
Engine: T444E
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As mentioned, there will be blow by when the engine is under load. Exhaust + oil can also be seen coming out of the hose when the pistons are no longer sealing well (low engine compression).
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Old 06-28-2016, 10:09 AM   #5
Bus Crazy
Join Date: May 2014
Location: West Ohio
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Engine: 6.9 International
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Pull the oil fill cap while it's running to check if it's plugged. Otherwise I wouldn't be overly concerned about it.
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