In newer Corolla and Civic. Why is that? It's a pain to replace those hidden under the intake manifold.
PCV screwed into crankcase rather than valve cover
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My 95 Mustang with a 5.0 Windsor has that, it is on the back of the intake manifold. Just another way of doing things.
twouvakind
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2.4L Theta, Mitsubishi and Kia same way as well. Plastic valve cover may be a factor.
Originally Posted By: bdcardinal
My 95 Mustang with a 5.0 Windsor has that, it is on the back of the intake manifold. Just another way of doing things.
This is not what I mean. I mean the PCV outlet is low on the engine rather than on the valve cover. It's almost like they want fresh air in the head and blowback removed directly from crankcase. While it sounds like a good idea, some people claim more oil is sucked up via PCV.
My 95 Mustang with a 5.0 Windsor has that, it is on the back of the intake manifold. Just another way of doing things.
This is not what I mean. I mean the PCV outlet is low on the engine rather than on the valve cover. It's almost like they want fresh air in the head and blowback removed directly from crankcase. While it sounds like a good idea, some people claim more oil is sucked up via PCV.
Originally Posted By: friendly_jacek
some people claim more oil is sucked up via PCV.
It's been my experience that such systems result in less oil in the intake.
The simple reason why is that any oil that escapes the crankcase (and the PCV baffle system) now has to travel a lot farther upwards in order to end up in the intake, and is more likely to condense out and run back down the pipe again.
some people claim more oil is sucked up via PCV.
It's been my experience that such systems result in less oil in the intake.
The simple reason why is that any oil that escapes the crankcase (and the PCV baffle system) now has to travel a lot farther upwards in order to end up in the intake, and is more likely to condense out and run back down the pipe again.
This is something inline engines have been chasing for a while.
Due to them only having a single cylinder head, it's difficult for the PCV system to work as effectively on a double-bank engine.
On a double-bank engine, fresh air enters one valve cover, flows down into the crankcase, up into the other cylinder head, and out of the other valve cover. Fresh air moves through the entire engine, scavenging gases and moisture from the entire assembly.
On a single-bank engine, fresh air usually enters one part of the valve cover, and then goes out of the other side of it. Fresh air never makes its way down into the crankcase at all. The crankcase can remain a pocket of gases and moisture throughout engine operation that is never positively vented. What makes its way out simply does so as it can.
The have been a number of single-bank engines that have airflow entry or exit through the crankcase. VW and Volvo engines come to mind.
Way back when, you even had engines that had their road draft tubes exiting from the crankcase.
Crankcase ventilation is for the crankcase, after all.
Due to them only having a single cylinder head, it's difficult for the PCV system to work as effectively on a double-bank engine.
On a double-bank engine, fresh air enters one valve cover, flows down into the crankcase, up into the other cylinder head, and out of the other valve cover. Fresh air moves through the entire engine, scavenging gases and moisture from the entire assembly.
On a single-bank engine, fresh air usually enters one part of the valve cover, and then goes out of the other side of it. Fresh air never makes its way down into the crankcase at all. The crankcase can remain a pocket of gases and moisture throughout engine operation that is never positively vented. What makes its way out simply does so as it can.
The have been a number of single-bank engines that have airflow entry or exit through the crankcase. VW and Volvo engines come to mind.
Way back when, you even had engines that had their road draft tubes exiting from the crankcase.
Crankcase ventilation is for the crankcase, after all.
Originally Posted By: DoubleWasp
The have been a number of single-bank engines that have airflow entry or exit through the crankcase. VW and Volvo engines come to mind.
And Honda engines around 1990. I do not know why Honda moved away from that system, other than possible cost-savings.
The have been a number of single-bank engines that have airflow entry or exit through the crankcase. VW and Volvo engines come to mind.
And Honda engines around 1990. I do not know why Honda moved away from that system, other than possible cost-savings.
Our old Nissan truck had the PCV valve down in the block. It was a PITA to change compared to a normal one.
BL B-series and the Lada engine both had a low crankcase vent IIRC. Wasn't a problem changing the PCV valve because there wasn't a PCV valve.
Current car vents via the rocker cover but there still isn't a PCV valve.
I wonder what I'm missing?
Current car vents via the rocker cover but there still isn't a PCV valve.
I wonder what I'm missing?
Originally Posted By: Tegger
... The simple reason why is that any oil that escapes the crankcase (and the PCV baffle system) now has to travel a lot farther upwards in order to end up in the intake, and is more likely to condense out and run back down the pipe again.
Maybe so on some models, but on Prius the (short) tube from the crankcase to the low-mounted intake manifold is approximately horizontal. Nevertheless, oil separation by the baffle system must be pretty good, because overall oil consumption is so low (so far!).
... The simple reason why is that any oil that escapes the crankcase (and the PCV baffle system) now has to travel a lot farther upwards in order to end up in the intake, and is more likely to condense out and run back down the pipe again.
Maybe so on some models, but on Prius the (short) tube from the crankcase to the low-mounted intake manifold is approximately horizontal. Nevertheless, oil separation by the baffle system must be pretty good, because overall oil consumption is so low (so far!).
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