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What accumulates in a catch can?

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Old Dec 20, 2011 | 11:57 PM
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Default What accumulates in a catch can?

I had always just assumed it would be just oil but what I dumped out a week ago was far from just oil. I have a cheapo ebay can that I stuffed with scratch pad material to catch oil vapors from my crank case. I was tearing things down for the winter build last week and emptied it out after about 1000 miles of driving. Out came probably a full cup of rusty looking water that had a burnt oil smell to it. Are these the vapors that accumulate in your crankcase that a PCV system gets rid of? Just want to make sure nothing is totally out of the ordinary. Thanks!
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Old Dec 21, 2011 | 12:49 AM
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if your car sits outside, then the catch can may be accumulating some condensation in it, if so then this is normal.
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Old Dec 21, 2011 | 01:15 AM
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It sits outside when I drive it to work and in an insulated but non-climate controlled garage the rest of the time. Didn't think of that though. Thanks!
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Old Dec 21, 2011 | 02:30 AM
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Originally Posted by Adam86
It sits outside when I drive it to work and in an insulated but non-climate controlled garage the rest of the time. Didn't think of that though. Thanks!
yea when i emptied mine for the first time and found like 2 oz of water in there, i freaked out. my tuner then told me it was condensation, cause if i did indeed have water in my engine, it would not run very long!
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Old Dec 21, 2011 | 04:08 AM
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Condensation forms in the crank case, totally normal. When the engine warns up, it vaporizes, and collects in the catch can. Without the catch can it just gets sucked back into the engine and sent out the exhaust.
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Old Dec 21, 2011 | 07:20 AM
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In addition to condensation, there is the water that is the byproduct of combustion which is accumulated when the engine operates at lower temperatures and the oil temperature is below 212F. Finally, there can be some fuel from fuel dilution that hits the oil catch can before the engine is warmed up.
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Old Dec 21, 2011 | 10:45 AM
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Good to hear. Thanks a lot guys! Before I put the scratch pad in it wasn't catching anything.
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Old Dec 21, 2011 | 12:09 PM
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Originally Posted by Adam86
Good to hear. Thanks a lot guys! Before I put the scratch pad in it wasn't catching anything.
That makes sense because dropping oil out of the vapor stream requires coalescing material. This why filters designed to drop water out of the vapor stream, which only requires a change in pressure/temperature, such as those used on pneumatic lines do not worik well as oil catch cans.
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Old Dec 21, 2011 | 12:53 PM
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Originally Posted by Darkman
That makes sense because dropping oil out of the vapor stream requires coalescing material. This why filters designed to drop water out of the vapor stream, which only requires a change in pressure/temperature, such as those used on pneumatic lines do not worik well as oil catch cans.
Not all catch cans are created equal. Most catch cans help a little, only a few help a lot!

- Jeremy
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Old Dec 21, 2011 | 05:07 PM
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Just received my catch can today.
I looked for the normal place to install and found nowhere to install it.
I have more **** + AC in there than your hand can grab.
For the life of me, I cannot fit the can into the engine compartment.
It's a CA car and as such there is a ton of crap attached to the engine.
There is already some fricking thing attached to the passenger side head that wreaks of smog ****.
Any ideas?
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Old Dec 21, 2011 | 05:53 PM
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Fender well? Well you want it somewhere accessible
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Old Dec 21, 2011 | 06:03 PM
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No room there either..
I tried that.
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Old Dec 21, 2011 | 06:06 PM
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Relocate the battery to the trunk to make room for more engine compartment goodies.
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