Alan

Fresh air into the breather on the cam cover (from the throttle body) and blowby - it certainly isn't all blow-by all the time (though it may be at very high RPM...)

Alan

Alan

Fred this is apparently the name Porsche used for the S4 rear filler neck breather valved port (on S4 not GTS). I don't realistically see how ice is ever a real factor here - maybe someone can explain it.

See https://rennlist.com/forums/showthre...eferrerid=6055 last few page for more info... interesting.

Alan

FredR

So have I! I was never enamoured with my S4 motors oil consumption the PO reckconed "they all do that" and to be fair, most S4's I have come across do seem to use oil to varying degrees.

Before we transplanted my S4 motor into the GTS chassis we had the motor partially stripped- no signs of distress in the bores which measured well, we did not remove any pistons [a mistake with hindsight?] and the valves looked good- they were re-lapped and new seals etc installed. I hoped for better oil consumption but it did not materialise. So, I tried the conversion to the GTS system using the filler neck from my TBF'd GTS motor. I stuck a larger bore vent on the front of the drivers side cam cover and this mod seemed to make the oil consumption worse. never thought it cvould be because the GTS system is crap until Greg B commented about that being the case.

A short while ago I modified this again using John Kuhn's crankcase baffle, bored a 1 inch hole in the base of the filler neck to vent to the Pro Vent. The pro Vent does not take out any oil at all and the gas vent pipe shows no signs of oily mist. The engine then seemed to run a bit better but I have not put the ST2 on since this mod. Then last weekend after my water pump and timing belt DIY job, I modifed the breather a bit more such that the hose that bridges the cam towers now tees into the inlet to the pro vent. At the moment the motor feels as though it is running better than ever at higher rpms- somehow smoother/crisper. Whether I will see more oil coming out of the pro vent or less oil consumption remains to be seen.

I was concerned as to whether John's baffle might be a bit restrictive with the wire mesh in the basket.

However I did convert to the GTS breather system and my oil consumption seemingly got worse- and that on a S4 motor.

With Roger's EIS system fitted, I am wondering if I can recycle the pro vent gas out to the air filter inlet given the element is "oiled".

Trust this is relevant to the thread- I will also try to take some pics of my GTS pistons [about 75k miles on them] to see how they compare to the ones Rob photographed if anyone is interested.

Regards

Fred

FredR

Alan,

Thanks for that- the thing has always puzzled me as to what it is intended to do. Ironically I kept the GTS filler neck stock and trashed my S4 neck to make my current system with the John kuhn baffle currently fitted.

Regards

Fred

ptuomov

On S4, it's called the de-icer valve because it _doesn't_ freeze! ;-)

Here's what I think they were thinking. The crankcase gasses have a lot of water vapor. When the engine is turned off in a cold climate, the water condenses in the breather hoses and flows towards the valve cover breather elbows, and may be held there perhaps because of some surface tension, oil crud, etc. Then, the water may freeze there, since those are metal parts and may cool relatively quickly. If the passenger side rear cam cover fitting freezes, there's no good way for the crankcase to breathe out blowby at full throttle -- except thru the secondary channel which starts with the one-way "de-icer valve" and doesn't have any metal parts.

Alan

Yes please do post more piston pictures

I don't think EIS or stock makes any difference to the answer - only recirculate crank gasses ahead of the MAF if you are sure they are clean of oil residue. There is a difference between a liquid oiled filter and oil mist. I would not have done this when my Provent filter was very oily - mainly because I could detect oil film on the outlet plumbing. I now do recirculate into the CAI because it is now totally clean after thousands of miles.

Alan

Alan

Yes but given the configuration where both elbow portions are at ~ 45 to vertical how would it not just drain back under residual heat... I can't envisage a case where it would block - maybe I have been in Phoenix just too long and have forgotton about the cold...

Alan

Leon Speed

Is it?

Alan

Yes I was actually surprised at this too - but I suppose a K&N type there is possible (not sure if its really desireable though...). Again I don't think it matters to this discussion either way.

Alan

MFranke

I don't have this issue on any of my cars. Little to no oil consumption. They are pre GTSes. S4s and GT, driven spiritedly with good run distances but no racing. It must be something to do with driving style or the engine design change.

Alan

Yes its primarily a GTS thing but there are certainly S4/GT cars that do seem to exhibit consumption issues - but not so many percentage wise. There must still be something that can trigger it for some cars...

Never really heard of a stock street pre-S4 with oil consumption issues. Now pre-S4's cars actually did have an oil separator as stock equipment.

Alan

siscogts

Maybe cause my poor language comprehension, I cannot understand the difference between the elbows...

Alan

There are functionally only two types: a straight through type (unrestricted) and a necked down orifice type (restricted). There are two versions of the unrestricted types that fit in different cam cover positions. The orifice type was fitted in the passenger rear location on most cars (but maybe not all).

Orifice = 0R
Straight Through = 1R/2R

Alan

FredR

Some photos of one of my GTS pistons. The side skirts show signs of very light scratches but that may be normal. the crowns have a fairly equal light coating of carbon with [presumably] some oil ash build up around the valve cut outs.

No idea if these useful. I have not attempted to remove the rings and could not behind the oil ring. The compression ring lands look quite clean.

Regards

Fred

jeff spahn

Are you going to drill the oil holes Fred?