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Discussion Starter · #1 ·
Hi,

I have a 2002 corolla with ~100K miles. I noticed that when I when I opened the oil filler cap, there was smoke/vapor coming out of the engine for a few minutes. The thermostat showed that the engine was at a normal operating temperature. Should I be concerned about this or is this normal?

Thanks
 

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Resident asshole
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And what does looking inside the oil filler cap tell you? Absolutely nothing, keep that thing closed when the car engine is running. And in newer cars you'll just cause shit on yourself when you open a wrong path for PCV operation.
 

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it si normal. that is what the PCV system is for. WHen oil gets hot there are impurities that will burn off and cause the vapor/fumes. Normally they will go through the PCV system and back into the intake and be burnt off through there. NOthing to worry about.
 

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Discussion Starter · #7 ·
Flashmn said:
And what does looking inside the oil filler cap tell you? Absolutely nothing, keep that thing closed when the car engine is running. And in newer cars you'll just cause shit on yourself when you open a wrong path for PCV operation.
The car was off. I was just adding a little oil.
 

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Discussion Starter · #8 ·
Cyorke said:
it si normal. that is what the PCV system is for. WHen oil gets hot there are impurities that will burn off and cause the vapor/fumes. Normally they will go through the PCV system and back into the intake and be burnt off through there. NOthing to worry about.
Thanks for the help!!
 

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Actually thats not what the PCV system is for. PCV system vents out the blowby gasses that come past the pistonrings, since those gasses contain pollutants and other noxious particles they're ingested by the PCV system and burnt in the cylinders. PCV system is just a emissions system, old cars vented it out through the oilcap / etc hose.

The car was off. I was just adding a little oil.
well hot water steams, same thing. Add oil when the car is cold, since when you add oil when the engine is warm, a portion of the oil will be in the head. (unless its below the empty mark, or very close to it)
 

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Actually thats not what the PCV system is for. PCV system vents out the blowby gasses that come past the pistonrings, since those gasses contain pollutants and other noxious particles they're ingested by the PCV system and burnt in the cylinders. PCV system is just a emissions system, old cars vented it out through the oilcap / etc hose.
Yes but those gasses that are blown by end up in the crankcase so if you were to open the oil cap while the car was still warm you will see the steam scming out of the valve cover. When you open the cap you are jsut giving those gasses another way to vent out, which unfotunately are going to bevented out to the atmosphere and therby defeat the purpose of the PCV system.
 

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Yeah, ofcourse they end up in the crankcase, but theres a canal from the crankcase to the valvecover.
When you open the cap you are jsut giving those gasses another way to vent out,
yeah, however it shouldnt vent it after the engines been shut off, theres no pressure in the crankcase after shutoff.
 

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yeah, however it shouldnt vent it after the engines been shut off, theres no pressure in the crankcase after shutoff.
True when you turn the engine off anything taht comes out of hte crankcase is most likely going to be steam. There is almost always some amount of water in your crankcase at any given time. When it heats up in the crank case the water boils and you get steam.
 

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Don't worry about it, it's likely just a little blow by. Any engine with close to 100K on it is going to some ammount of blow by.
 

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There is almost always some amount of water in your crankcase at any given time.
Water vapour maybe, but whatever minute amount there is will be "eaten" by the oils or blown out, but aleast I dont want water to be in my crank case..... that means headgasket kaput and mayonnaise in the oilpan... But i suppose you mean water vapour.
 
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