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Slight Oil Leak- Crankcase Vents & Oil Filler Neck

13K views 8 replies 3 participants last post by  LW_Black4 
#1 · (Edited)
Confirmed that the crankcase vents at the top of my EJ205 cylinder heads (both sides) and the oil filler pipe neck have a slight leak on my new engine. Marked it 1. and 2. on the diagram below.

Likely gaskets weren't replaced during the rebuild, as they were also leaking here before.

Gaskets are not expensive and i can change them myself, without having to go under the car.

Some disassembly is required to get at them though.

It's wet down the valve covers and looks like it gets to the exhaust manifold on the passenger site.

With the right gaskets and filler neck O-ring, how long should I expect for this repair and are there any special considerations?
 

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#4 ·
Well I'd say the easiest way to do it would be remove the IC and Intake manifold.
The fuel injector covers have to come off in order to get to the vent covers easily and in order to get them off you pretty much have to remove the intake manifold.
I know the bottom 2 bolts on the passenger side are one of the reasons.
Not to sure about the driver side I think that one might come off.
When I put my top end back on I left the bottom bolts out for easy access to the injectors.
You could try to wrestle around this but I think your life might be easier to just remove like said so you have more room to work and not have to worry about dropping bolts and such.
 
#5 ·
As for the oil filler neck you probably could get to that easy with no issues but the vent cover on the driver side might be a little right as well.
I just took a look at my engine and your biggest obstacle is gonna be the injector covers.
 
#7 · (Edited)
Vapor separators were weeping oil on the new engine, so I changed the gaskets.

Also got some mayonnaise in the vent system, which I didn't expect since I walk to work and only take long trips. Why might I be getting water vapor into the crankcase?

I was clear the gaskets were from the old engine so they needed to be changed, but I don't like the gunk in the vapor separator chamber.

Now I'm wondering if there's something wrong with the PCV valve? I don't expect weeping given this system is under vacuum most of the time - even if the gaskets were old. The PCV valve is recent - within the last year, or 30,000km.
 

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#8 ·
Thanks to Epic and Keith for helping identify how the crankcase ventilation works.

The EJ205 has a center crankcase vent that is connected to the intake manifold and the intake duct through the PCV valve, as per the photo below.

The valve cover line that connects the vapor separators on each cylinder head is connected to only the intake duct, from the schematic diagram in EC(H4DOTC)-6 below.

Looks like air flows into the vapor separators from the intake duct at part throttle, and at WOT the flow is reversed to expel crankcase gases up out of the vapor separators as the blowby increases with engine rpm.

So the crankcase takes in cool air through the vapor separators from the intake duct at part throttle and expels hot crankcase gases through them into the intake duct at WOT.

Still doesn't explain why my vapor separators were leaking. I'd expect them to be under some vacuum at vacuum or boost. Is this correct?

Shouldn't the crankcase be under some sort of light vacuum in all operating conditions?
 

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#9 ·
By the way, car Club guys say there is significantly more blow-by in a built motor because of the forged pistons, especially during warmup, and not to worry about the crankcase ventilation.

"That explanation is only partially correct.

A crank case should always be almost atmosphere neutral, that's the main purpose of the "Positive Crancase Vent", if there is a pressure differential in the crank case (positive), the intent is to expel that pressure and route it to either "Atmosphere" or to be more politically and environmentally correct, reroute it to the intake (vacuum side) where it can get recycled into the system.

The Vapor Separators should NEVER see any pressure or boost, because if you increase crankcase pressure through the Vapor Separator or blow by, "Overpressurization of the crank case" occurs which can result in thing like "oil burning" specially through the turbo slingers. Which results in nice blue smoke everytime it happens. Some of it is unavoidable as in Track Cars, but they too do their best to evacuate any pressure going to crank case.

So your head "vapour" separators are subject to the bernulli principal (you can read up on that) and the effect of fast moving air on pressure (vacuum), and never see any pressure.

The "Aeoli" or white stuff in your tubing is a result of water vapour mixing with oil, the most common "normal" cause of this is short trips. When you do a short trip, your engine never warms up enough to vaporize all the water in the system. Remember, the byproduct of combustion is..... (you can research this too, but the most prevalent byproduct is H20). Forged internals make this much much much worse too.. LOL Welcome to the Forged piston crowd. Overbuilding does not equal reliability, you can't even call it overbuilding, it's "Purpose building" does not equal reliability. LOL

They are leaking because either the Orings or the Fujibond has lived beyond their expected life span or your rubber tube's need to be refreshed. LOL"
 
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