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One thing is really starting to irritate me on this car. euro spec 2.5, 60,000 miles on an excellent engine with no problems, uses oil as per the factory manual. but I have noticed it doesn't take more than a few weeks of driving after an intake service, for the accordian section to end up with fresh oil in it again. I know it doesnt really casue any problems, but it annoys me knowing its there, and having to clean out the AAV 3 times a year. What is it about these engines that they put so much oil up through the crank case breathers? Anyone had success with a better oil seperator or additional one to reduce this?

If you're concerned about keeping it clean, simply replace it with a catch can. Same job done, just goes into the can rather than back into the intake.

ROCK ON
R~R

mjr wrote:I know it doesnt really casue any problems,

Actually, it is more of a problem than most people accept. Hot oily blow by gas has an octane reducing effect (promotes detonation) and helps to cause carbon deposits in the combustion chambers, which can also promote detonation/pre-ignition.

mjr wrote:What is it about these engines that they put so much oil up through the crank case breathers?

Most engines tend to breath a bit. I did read an article about the early LS1 powered Holden Commodores here in Australia, having massive oil consumption issues even when new. The story said theat the cars suffered from a combination of pore ring seal and a badly designed crank case ventilation system. The fix was an effective oil/air seperator that scrubbed the blow by gas of the oil mist, causing the oil to condence and fall out of the gas flow, and then it was returned to the sump via a 1 way valve. The design was apparently very effective, reducing oil consumption from being about 1 litre per 1000km (they said it was bad!) down to an almost immeasurable drop in oil level between changes.

I've not seen under the rocker cover of the V6 (yet), but is there any baffling to prevent oil being flung directly up the crankcase breather tube from the camshaft?

I know it doesn't realy answer your question about 'why', but it may provide you with a solution to your (and probably everybody else's) blow by oil mist question without going to a smelly and illegal oil catch can.

ya know...i dont think there is a baffle...and i know on mine it too blows far to much oil and was going to go with catchcan of my own design....the 1way valve to drop it back into the sump is a GREAT idea that i hadnt thought of

sh0rtlife wrote:ya know...i dont think there is a baffle...and i know on mine it too blows far to much oil and was going to go with catchcan of my own design....the 1way valve to drop it back into the sump is a GREAT idea that i hadnt thought of

Shouldn't the contents of the catch can be never returned into the oil system?

PietereQ wrote:

sh0rtlife wrote: Shouldn't the contents of the catch can be never returned into the oil system?

That's supposed to be the point yes.

Duk, I know in Australia a catch can is only illegal if it has the small breather that vents to the atmosphere. If it doesn't, not a problem.

ROCK ON
R~R

Why not return it to the oil system?

Because a black goo made of oil, vapor, fuel and whatever else is not a good additive to oil? Many people just drain it periodicaly.

Well, it is aerosol from inside the crank-case or from under the valve covers so it can't really be all that bad or your engine needs a rebuild. Normally it is automatically drained back to the sump from the separator (as in the Alfa std install) and only a small amount is passed into the intake.

that "small amount" is messy IMO.

not if it doesn't get out.....ie its put back into the sump.

mjr wrote:that "small amount" is messy IMO.

Well, the small amount is led into the intake (stock), we were as far as I can understand, talking about draining the stuff that is caught in the can back into the sump.

What you do with the other end of the hose is up to you (up yer nose? ).