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So as most of you know, some of our 997s end up with the dreaded bore scoring. I took it upon myself to do some scoping and investigate some of the symptoms I have been experiencing. So I have owned the car for 2 years now and runs great. Now keep in mind before I did this test I was parked on a hill overnight and some oil leaked into the cylinder which I think is pretty normal, in one of the photos you can see the oil resting on the bottom of the cylinder wall. The question is, there is no super obvious scoring. There is a lot of carbon build up. Could this be a faulty oil separator?
Symptoms
eats about 1qt roughly every 2k miles
never smokes unless on a hill
sooty driver side tips
its quiet, no tapping, runs smooth
visible carbon buildup on top of pistons
heavy carbon on valves visible when rotating the motor around
I don't think you should have oil sitting in there, hill or not. That oil will burn, create soot, and some smoke. I think you are looking at your problem. Which bank is that photo from? A bad AOS sends oil to all cylinders.
Not sure if i can add much, but your plugs look like either you have carbon fouling or oil deposits probably due to the leaking oil. I also have an 07 4s with 75k on it and mine usually wear with a brownish/greyish color.
As to the AOS, i just replaced mine and what i noticed in my case was that i had oil deposits on the intake tracts right behind the throttle body and i could see the oil puddling near the band clamps. Also both of my tailpipes had soot, not just one side. However my oil consumption wasn't that bad, maybe 1quart every 4k using Motul 5w-40. Check your AOS with the manometer test, however the fact that you have heavy soot on side of the pipe is odd. The AOS can wear with minor perforations on the diaphragm(in my case) and just just completely open up which results in huge amounts of oil being sucked into the intake and erratic idle and high crankcase pressure.
The NA 997.2s we had burned Zero oil over 10k miles.
It's not a joke. Porsche says it's within tolerance to lose 1qt per 1,000 miles which is crazy to me but mine does consume about 0.5-1qtper 1200-1500 miles.
Do some searching on the 996 forum, esp on FSI and LNE posts about sooty tailpipes.
The short answer is the ethanol they force on our cars corrodes the injectors leading to very rich cylinders (hence soot and black carbon) which does not throw a CEL. The fuel washes the bores of oil lube and they eventually score/fail.
Apparently if you catch it early you can get your injectors checked and/or replaced and catch it before you score.
Nice job tackling your own bore scoping project. What did you use to capture those images? Would be nice to see a little diy explanation. I would not think your symptoms are alarming, but rather normal for a 2007 with 50k. The AOS return line enters at the plenum just after the throttle body. Seeing residual oil in the plenum after the throttle body is perfectly fine as well. It would not surprise me if a few drops of hot oil dripped down your intake manifold from the plenum area, through an open valve and rested on the bottom of that Flat cylinder wall over night. A little bit of soot on the tail pipes is more common than you might think. Excessive soot should be looked in to though.
-I use any good fuel system cleaner once every 5k to keep carbon build up at a minimum. Might be worth a try.
-Smoking after being parked on a hill, or a tough track day is most likely the AOS being overwhelmed with oil temporarily..
Usually goes away after a good drive. If the smoking returns several days in a row after decent amount of driving then definitely consider swaping out the AOS.
-Yup. +1 997.1 0.5 - 1 quart per 1000 miles. Perfectly normal, but some burn more than others based on driving habits. If you are an aggressive driver and like to hit red line a lot, take hard and fast corners often, do a track day or some spirited canyon driving a few times a month, then about 1 quart, but preferably less, every 1000 miles is what several techs have told me is within range, expected and normal.
The NA 997.2s we had burned Zero oil over 10k miles.
Is that a serious question? Also, your pivoting from the issue. No one is asking about a DFI .2 engine. This was .1 specific. (OP has a 2007 C4S Cab with a manual trans. 50k miles)
It's not a joke. Porsche says it's within tolerance to lose 1qt per 1,000 miles which is crazy to me but mine does consume about 0.5-1qtper 1200-1500 miles.
Yep. According to this spec sheet, up to 1.6 qts per 622 miles is acceptable ... although, I think I'd $h!t myself if my car was burning oil at that rate. (link below)
06-19-2018, 11:11 PM
Borescope - some odd findings
