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I am trying to understand how oil gets into the intake plenum. Can someone describe this system to me?
Reason: I am getting paranoid about intake valve carbon buildup and want to understand the system that contributes to this issue. From reviewing the Porsche parts diagrams, oil vapor comes from two sources... 1) the air/oil separator, and 2) "crankcase housing bleeding ventilation" on each of the heads. Through various hoses and junctions including a "vapor purge valve solenoid", and then fed back to the throttle body just after the butterfly for injection into the plenum. Is this correct?
I am looking for something to clean, or empty, or check for functionality of this system. Yes, the voices in my head are getting louder.
Your engine lasts 200,000 miles. What are you paranoid about?
I want to know where there are maintenance items for a car at this mileage. Given direct injection is pretty infamous for clogged intake valves, I am wondering if there is any maintenance I can do here. Anything that can clog? Examples of other items include changing power steering fluid and engine coolant... I don't agree they are lifetime fluids so I changed them out. Changing the manual transmission fluid way earlier than 120K miles as denoted in the manual is a good thing.... etc.
I am trying to understand how oil gets into the intake plenum.
At a high level... Oil vapor is present in the engine crankcase air space. Because of vacuum in the throttle body that is directed via tubing to the AOS and ultimately a hole in the crankcase case, the oil vapor is sucked into the AOS. The AOS attempts to separate the oil vapor from the air. Any liquid oil is drained back into the crankcase. Any remaining oil vapor in the air continues towards the throttle body via tubing. The oil vapor can condense on the surfaces of the intake system (throttle body, plenum, intake runners). This is why you can find liquid oil in the intake tract.
When the AOS fails, it no longer separates the oil vapor and entrained oil from the air - hence one gets a lot of oil in the intake system leading to the smoky exhaust condition. Sometimes there's enough oil making it to the cylinder to cause hydrolock and engine damage.
So what does that "purge solenoid" do? It appears to be a valve(?) that is on the line to the throttle body.
And, what are the channels for oil vapor getting into the intake plenum? Appears to be that tube to the throttle body, are there other ways? The diagrams are not clear about pipe routing. Does all vapor pass through the AOS? then though that solenoid? Then on to the throttle body?
And, what are the channels for oil vapor getting into the intake plenum? Appears to be that tube to the throttle body, are there other ways? The diagrams are not clear about pipe routing. Does all vapor pass through the AOS? then though that solenoid? Then on to the throttle body?
Oil vapor handling is described with this diagram. I don't know where every line terminates but one/some must terminate at throttle body for the vacuum.
I am not sure of this... the solenoid I was referring to, is on the line that attaches to the side of the throttle body. 9A1 110 091 02 "breather line complete" is actually called "Porsche Vapor Canister Purge Solenoid" on parts supplier pages https://www.pelicanparts.com/More_In...110-093-04-OEM.
Where is this vapor canister? Gas or oil? On the parts list, it is item #1 under "Crankcase housing Bleeding Tank ventilation" - two separate things? Oil and gas? Or a single system.... very confusing. I have trouble believing they are routing gas vapors to the intake plenum... while that would be good for limiting carbon buildup on the intake valves, seems like it may be a cause of fires or other loss of combustion control.
Peace
Bruce in Philly (now Atlanta)
Last edited by Bruce In Philly; 02-10-2024 at 08:55 AM.
Oil vapor handling is described with this diagram. I don't know where every line terminates but one/some must terminate at throttle body for the vacuum.
In this diagram, hose #8 is the one that returns oil vapor to the intake tract.
I am not sure of this... the solenoid I was referring to, is on the line that attaches to the side of the throttle body. 9A1 110 091 02 "breather line complete" is actually called "Porsche Vapor Canister Purge Solenoid" on parts supplier pages https://www.pelicanparts.com/More_In...110-093-04-OEM.
Where is this vapor canister? Gas or oil? On the parts list, it is item #1 under "Crankcase housing Bleeding Tank ventilation" - two separate things? Oil and gas? Or a single system.... very confusing. I have trouble believing they are routing gas vapors to the intake plenum... while that would be good for limiting carbon buildup on the intake valves, seems like it may be a cause of fires or other loss of combustion control.
Peace
Bruce in Philly (now Atlanta)
Here is a link that might help explain a little bit about the evap system.
Wow, cool... thanx. So..... Well..... If this is introducing gasoline vapor into the intake plenum, then this may a reason we with .2 engines are not having intake valve coking. Hmmmmm......... Thoughts?
Peace
Bruce in Philly (now Atlanta)
Last edited by Bruce In Philly; 02-10-2024 at 11:58 AM.
02-09-2024, 05:28 PM
Crankase Bleeding/Breather PVC - Please Explain
