2007 Rs4 , 60,xxx miles. Car is 100% stock , Scheduled Maintence has been followed to a " T " with in-between Mobil 1 oil changes performed, w/ OEM filters.

Carbon Service performed at 30k with a Dyno-Documented 40hp gain after cleaning.

Second Carbon service performed just after 60k and it looked as bad as it did @ 30k , with a common denominator that the valve stems themselves looked wet when the intake was removed both times.

Here's the rub: After the second carbon service the engine oil level light came on and I added 1 qt oil. ( After checking the dipstick cold it showed under the minimum mark ) I went on a 18 hour road trip , mostly highway miles @ higwhay speeds. During those 1500 miles, I had to add another 5 quarts of oil, each time as the oil level light came on, checked level, added a full quart.

After car sat over the weekend, not being started or driven, the engine started ok, but is idling poorly. After a few miles of driving, the yellow CEL started flashing, and I went home. Checked codes to show misfire cylinder 1.

Checked all electrical connections and chose to remove the spark plug cylinder 1, to find it wet with oil. I'd perform a compression test, but there is enough oil in cylinder 1 that I don't think it would be accurate.

A quick call into the Dealership , gave me the reply that they'd want to remove the cylinder head for inspection of damage.

Before I pull the trigger on THAT leap of faith, anyone here experienced anything like this or have internet opinions on this concern?

Thank you in advance for your thoughts,

S

 

They are right that they have to pull the head to see where the issue is. Could be a ring or it could be a valve guide. Though they can do leak down tests too but what ever the issue is they will have to pull the head to fix.

It's one of those problems that does not make sense and is not typical of this engine. We typically burn off 1/2 qt in these engine - for some reasons they seem to stay at 1/2 qt low on the dip stick.

 

Man, that really sucks, so sorry to hear. How much time/mileage elapsed between the 2nd carbon cleaning and the oil consumption issue? Was it immediately upon return of the vehicle?

 

The road trip was immediately ( 2 days ) after pick up from CC, the first oil level light was within the first 2 days of pick up.

Which I why , while I completely trust the services performed, I am hoping for an association between something that was maybe put together incorrectly, a line that's pinched, the oil seperator is clogged, etc...

Between 30k and 60k , the engine may have used 1 qt between annual service, if driven on longer road trips.

Which brings up this question: What could a carbon service cause or lead to this oil consumption seemingly over night?

Examples:
1. Chunk of carbon made its way into cylinder chamber and damaged ring?
2. Chemical used to clean ports made it's way up into valve stem seal area?
3. Chemical used to clean ports made it's way past valve seat and into cylinder chamber and caused XYZ?
4. PCV line or lines clogged with freshly cleaned crud, in turn blocking or causing backup of pressure, causing oil to pressurize into closest cylinder ( 1 ) in this case?

I just have not seen or heard of this happening in any fashion to any other Rs4.

The only common denominator is that a carbon service was just performed AND that I have used this oil ( http://www.renewablelube.com/gasoline.html# ) on the previous oil service 2mths/5,000 miles before the carbon service and an oil service the same visit as the carbon service was performed.

S

 

Understood, but as I listed in my reply above, what is the cause?

Dumb luck or did something happen during the carbon service that could have led to this symptom showing it's head?

A valve guide wouldn't just let go after a cleaning, or would it? A piece of jagged carbon carried into the valve seal area, damaged the valve guide enough to allow oil to leak through...

I know I am rambling, just trying to make sense of it ,

S

 

I've read about a story second-hand - but not sure I believe it - the deal about a piece of carbon dislodged and ending up in the combustion chamber. As the story goes, the carbon supposedly scored the cylinder wall(s). If that's the case, pulling the head is only the tip of the repair iceberg. It's hard for me to believe because (1) it's difficult to get a something past the closed valves. Only one cylinder's intake valves are open at any one time. A decent mechanic would of course plug the port with rags or paper towels while cleaning the others. (2) the carbon is not all that hard. Yes it's hard to scrape off, but it's not exactly coke either. I've seen small screws and nuts pass through motors without harm. it's hit or miss with those (hard) items. (3) A piece of carbon inside the combustion chamber would quickly get smashed to powder in the tight quench area and blown right out the exhaust port. All JMO, of course.

5 quarts though is really bad. The only motors I've torn down that burned that much oil had broken piston rings, which in turn, tear up the cylinder walls. These were all motorcycle motors BTW.

A leakdown test would tell if the cylinder walls and/or rings are damaged. It's a simple, quick, and cheap test.

 

Elevens has some good advice, but the root cause will eventually involve taking the head off. Cause can be the carbon cleaning but that should be remote. Over reving a engine could do it too but since we have rev limiters - the only way t his could occur would have been if you downshifted and let the clutch out too soon and over rev the engine. The other thing could just be a random failure [ I had that happen to my daughters 98 A4 front diff with less than 80k miles on the car - first and only front diff failure I have ever read about]

 

I would highly suggest doing an oil change at a non Audi facility before hand. I have used RLI with great results and swear by it now, but the last thing you'd want is to give Audi some type of out as to what maybe caused the damage if there is any. It's not on their "approved list" becuase they never tested it. But this is all with the assumption you're still under warranty. If not, there was a brand new cylinder head (1-4) that sold on ebay Friday for $522. Pretty sure I know who the new owner is who pulled a fast one on me. He'll probably want $2k (It's a $4k part), but I guess cross that bridge if you get there.

 

Depending on what they use to clean the valves it could be that carbon has gotten into the cylinder if all the carbon was not removed before turning the engine over to the next cylinder during the cleaning and also if the fill the intake port with to much cleaner when they soak the valve the chemical can get into the valve guides and eat the seals. Heads most likely gotta come off.

 

Not sure about the RS4 I've changed valve seals on GM domestic V8's without pulling the head. I think the whole RS4 motor has to be pulled to remove a head.

It seems a long shot to think the head is ruined. Not sure why that could/would even happen in this case. Never seen valve seals leak 5-quarts bad though. Sorry to say that my money is on a scored cylinder or cracked rings.

I holed a piston one time (1965 445 Buick Wildcat) thanks to improper ignition timing. You should have seen the smoke then! The car behind me pulled up and the guy hopped out with a fire extinguisher, thinking my car was on fire!

The tell-tale symptom of leaking valve seals is smoke on cold startup. The oil pools around the seal then when the motor is started, the vacuum pulls the oil in all at once.

Reggie was right, the cracked rings I've seen were all a result of over-reving. That was back before there was rev limiters so it was easy to do. I did it myself about a half-dozen times

Yes, I've wrecked (and fixed) a lot of motors in my day! Good thing I got it out of my system decades ago, these modern motors are too expensive to break.