What is Oil Blow by
06-07-2012, 06:23 AM
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What is Oil Blow by
hi there..
ive been doing research on the net in general, here and looking for videos to describe Oil Blow by..on FI setups..?
what exactly is it.. how/why does it happen.. where is the oil coming from etc..
I know using an Oil Catch can.. gathers oil from blow by.. but is there a way or can it be prevented..?
I have a vortech setup.. im not using a Catch Can.. for the moment.
I just want to understand what it is.. and if I can go without using a catchcan..?
thanks.
ive been doing research on the net in general, here and looking for videos to describe Oil Blow by..on FI setups..?
what exactly is it.. how/why does it happen.. where is the oil coming from etc..
I know using an Oil Catch can.. gathers oil from blow by.. but is there a way or can it be prevented..?
I have a vortech setup.. im not using a Catch Can.. for the moment.
I just want to understand what it is.. and if I can go without using a catchcan..?
thanks.
06-07-2012, 06:37 AM
#2
Wiki and the Google to the rescue:
Air ventilationMain article: crankcase ventilation system
During normal operation, a small amount of unburned fuel and exhaust gases escape around the piston rings and enter the crankcase, referred to as "blow-by".[7] If these gases had no controlled escape mechanism, the gasketed joints would leak (as they "found their own way out"); also, if the gases remained in the crankcase and condensed, the oil would become diluted and chemically degraded over time, decreasing its ability to lubricate. Condensed water would also cause parts of the engine to rust.[8] To counter this, a crankcase ventilation system exists. In all modern vehicles, this consists of a channel to expel the gases out of the crankcase, through an oil-separating baffle, to the PCV valve, into the intake manifold. In a non-turbo engine, the intake manifold is at a lower pressure than the crankcase, providing the suction to keep the ventilation system going. A turbo engine usually has a check valve somewhere in the tubing to avoid pressurizing the crankcase when the turbo produces boost.
If an engine is damaged or enters old age, gaps can form between the cylinder walls and pistons, resulting in larger amounts of blow-by than the crankcase ventilation system can handle. The gaps cause power loss, and ultimately mean that the engine needs to be rebuilt or replaced.[7] Symptoms of excessive blow-by include oil being pushed up into the air filter, out the dipstick,[9] or out the PCV valve. In rare cases of serious piston or ring damage, the oil filter housing's sheet metal can even burst at its seam.
Air ventilationMain article: crankcase ventilation system
During normal operation, a small amount of unburned fuel and exhaust gases escape around the piston rings and enter the crankcase, referred to as "blow-by".[7] If these gases had no controlled escape mechanism, the gasketed joints would leak (as they "found their own way out"); also, if the gases remained in the crankcase and condensed, the oil would become diluted and chemically degraded over time, decreasing its ability to lubricate. Condensed water would also cause parts of the engine to rust.[8] To counter this, a crankcase ventilation system exists. In all modern vehicles, this consists of a channel to expel the gases out of the crankcase, through an oil-separating baffle, to the PCV valve, into the intake manifold. In a non-turbo engine, the intake manifold is at a lower pressure than the crankcase, providing the suction to keep the ventilation system going. A turbo engine usually has a check valve somewhere in the tubing to avoid pressurizing the crankcase when the turbo produces boost.
If an engine is damaged or enters old age, gaps can form between the cylinder walls and pistons, resulting in larger amounts of blow-by than the crankcase ventilation system can handle. The gaps cause power loss, and ultimately mean that the engine needs to be rebuilt or replaced.[7] Symptoms of excessive blow-by include oil being pushed up into the air filter, out the dipstick,[9] or out the PCV valve. In rare cases of serious piston or ring damage, the oil filter housing's sheet metal can even burst at its seam.
06-07-2012, 06:45 AM
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hi.. ok thanks for the reply..
sorry to sound stupid.. but that is still pretty techincal for my understanding..?
how does oil get into the air filter.. and back into the intake..?
what I have read here.. is that some guys.. get oil all in the intercooler piping etc.. and have to clean it out..
so how is that happening..?
sorry to sound stupid.. but that is still pretty techincal for my understanding..?
how does oil get into the air filter.. and back into the intake..?
what I have read here.. is that some guys.. get oil all in the intercooler piping etc.. and have to clean it out..
so how is that happening..?
06-07-2012, 07:15 AM
#4
If you study the picture of the stock PCV system in the FSM, it shows how oil vapors from the crankcase are potentially routed to both the plenum and the driver's side turbo intake (in most turbo kits). There is a large thread on crankcase ventilation. If you read through that, you will see some alternatives.
To answer your question, yes, you can remove the catch can. Just put breathers on both valve cover ports and vent to atmosphere. Not emissions friendly and kind of smelly...
To answer your question, yes, you can remove the catch can. Just put breathers on both valve cover ports and vent to atmosphere. Not emissions friendly and kind of smelly...
Last edited by rcdash; 06-07-2012 at 07:17 AM.
06-07-2012, 08:45 AM
#5
Normally aspirated or forced-induction its the same.
Just think of the engine as a controlled explosion: Gasoline plus air plus a spark. The result moves the piston. The exhaust cycle clears the combustion chamber for the next injection of gasoline and air for the next explosion.
The piston and cylinder is not a perfect seal. Its not perfect because the piston must move. Some gases (and anything inside the gases) will get by the piston ring. Whatever gets by the ring is referred to as blow by.
Just think of the engine as a controlled explosion: Gasoline plus air plus a spark. The result moves the piston. The exhaust cycle clears the combustion chamber for the next injection of gasoline and air for the next explosion.
The piston and cylinder is not a perfect seal. Its not perfect because the piston must move. Some gases (and anything inside the gases) will get by the piston ring. Whatever gets by the ring is referred to as blow by.
06-07-2012, 10:18 AM
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op, just google an image of a general pcv system. these guys have done a good job of describing what blowby is and how it happens, but as far as how that gets back into the intake, it would be best looking at a picture and the path the gases take through a general pcv system
basically, gasses get by rings, they are then in the crankcase. typically, each valve cover will have an opening, and both valve covers are connected with a hose in some way. one side will be a filtered air source, usually connected to the intake tube somehow before the throttle body. the other side will be a hose connected to the intake manifold after the throttle body and serves as a vacuum as the engine sucks in air. the vacuum pulls air from the crankcase, which includes those blowby gasses, and it gets its source of air from the filtered source on the other valve cover. this is how the system gets the blowby gasses out of the crankcase and how that oily air can get into your intake. hope that helps, but like i said, look at a general picture and it will be worth many more words.
basically, gasses get by rings, they are then in the crankcase. typically, each valve cover will have an opening, and both valve covers are connected with a hose in some way. one side will be a filtered air source, usually connected to the intake tube somehow before the throttle body. the other side will be a hose connected to the intake manifold after the throttle body and serves as a vacuum as the engine sucks in air. the vacuum pulls air from the crankcase, which includes those blowby gasses, and it gets its source of air from the filtered source on the other valve cover. this is how the system gets the blowby gasses out of the crankcase and how that oily air can get into your intake. hope that helps, but like i said, look at a general picture and it will be worth many more words.
06-07-2012, 02:34 PM
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"what I have read here.. is that some guys.. get oil all in the intercooler piping etc.. and have to clean it out..
so how is that happening..? "
Bad seals in the Blower (which are lubricated from the engine's oil) or from the driver side manifold vent which is fed into the Blowers filter?? Any oil getting into the airstream will be fed into the Intercooler..
so how is that happening..? "
Bad seals in the Blower (which are lubricated from the engine's oil) or from the driver side manifold vent which is fed into the Blowers filter?? Any oil getting into the airstream will be fed into the Intercooler..
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