greatwhiteshark

I found this while digging through the bowels of the site.

http://blogs.edmunds.com/greencaradv...n-buildup.html

ArthurPE

thnx, nice find & very interesting...

looks like they are aware of the problem, and are seeking to remediate...

aviator79

This has been a know issue in out Mazdaspeed6's for a while. We had to install an OCC and delete the EGR. These are things that you should look into doing as soon as you have the dealer clean it for you. It is a must on our cars and Im sure yours too. The oil seperator im sure will not work well enough and looking at those pictures I gaurentee you all have an EGR as well. I can help provide more info but im sure it is limated with the fact that I know nothing about your engines. This topic was just linked to on my forums and I am already a memeber here so I figued I would post. Not knowing the rules I do not want to post any links yet thou even thou I did before for the LI GB I held.

silverRS4

There are no EGR components per se, I believe the same result is achieved through valve overlap control (passive). The build up has nothing to do with exhaust gases and everything to do with the high amount of oil vapor in the air charge. The oil separator system already in the car is either completely overwhelmed or not functioning properly. It is as simple as that.

RS4POWER

SilverRs4-

Have you removed your intake manifold recently? How have you been liking Scott's recommended oil, Biosyn?
I have received the kit to send Terry Dyson a sample of my oil and switch over to the recommended oil. I want to get the valves cleaned before switching over though. What worries me is that my dealer has limited experience in this matter as they just did an rs4 and couldn't get all the CB off with the solvents recommended to them.

I talked to a gentleman that works for Audi Technical, (not sure what that means exactly) he told me to apply the BGK treatment and that walnut shell blasting was becoming the "unofficial" way Audi was attacking this matter. My dealer never heard of that approach so I forwarded this post to them. I shall wait for them to review and get back to me. What method did you apply when you cleaned the valves? I know you said it was a PITA. I am just hoping this becomes a one time issue after the clean up and oil switch.

Your thoughts please...

silverRS4

I had the manifold off the fourth time about a month ago when there was close to 3000 miles on the Biosyn. The valves were not clean, but it was more of a thin, oxidized film of oil, rather than thick, gooey, flow-blocking black crud (which was the case after 4000 miles of factory oil, 4000 miles of Mobil 1, and less than 1000 miles of Castrol TXT). I was pleased and will certainly keep using the Biosyn. I am sure Scott could fill you in on the chemistry that makes the build up rate noticably less. I also use the Biosyn fuel conditioner (2 oz) with each fuel fill of Shell gasoline to make sure the injectors stay clean. With the FSI aspect of the 4.2L engine, I believe that sparkly clean valves is just not a realistic expectation - even with Biosyn. But I am happy with how its working thus far. The aspect that really hasn't been discussed is the affect that the oil "contaminated" intake charge has on optimum spark timing. The advanced RS4 ECM's and knock sensors seem particularly sensitive. After endless logging, I have a few cylinders that have timing retarded 4-6 degrees under moderate loads and 9-11 degrees under heavy loads. That is significant. I live in the Midwest and am stuck with Ethanol blended fuel even in the 91-92 octane Tier 1 fuels (Shell included)- that could be part of it, I don't know.

As far as my cleaning method, it was just the old fashion way. In six of the eight cylinders, the intake valves were completely closed, so I just poured in several ounces of carb cleaner right into the intake ports and let the valves soak several hours. Then a majority of the crud comes off with aggressive scraping with an appropriately shaped metal tool. The valve stems block the ability to scrape the area behind them. Vacuum out the mess. Then I poured in fresh solvent and put a small Dremel-type wire brush tool on the end of a cordless drill. Scrub, scrub, scrub. The varnish layer of buildup on the valve surface is very, very hard. This method is limited and removes 90% of the build up at best. The walnut shell blasting would be far better. I have access to such blasting equipment and media, but its ridiculous that I or anyone else has to consider such a chore ...warranty work or not.

TexasFly

Okay - today I will be dropping the factory initial fill (brand unknown) on my 2008 with 750 miles and switching to RLI's 5w-40 .... thought that I try it from the beginning. Any downside?

RI A6

Earliest switch I've seen was at 2K miles. That owner is in Texas and now has around 25K on the engine with consistently good results in oil analysis.

TexasFly

Oil and filter change done at 750 miles. Let me know if you would like for me to contribute oil samples as I progress. What OCI should I follow on my RS4 with RLI? Would every 5K suffice? I am also using RLI's Biosync fuel additive with Chevron Premium 93 Octane fuel. Thanks for all of you help - I have been following this issue in oil guy forums.

nadrealista

interesting thread, I was thinking of replacing my B5 S4 with RS4 in couple years but this issue with carbon build up on intake valves makes me wonder if that would be wise decision.

besides warranty, what obstacles exit to have catch can venting to atmosphere instead this fancy cyclonic oil separator that does not work?