Just had the Walnut shell cleaning done at Motoring Magic at 60k miles. I've had an OCC installed since 30k and have been running methanol injection since about 40k. I'm sure the OCC and methanol help to reduce the rate of buildup but there was still enough buildup to impact performance.

The engine feels smoother and much stronger after the cleaning. The idle is smoother as well. I'm spinning the tires well into 2nd gear. Poor tires

The pic below is after the cleaning. It's well worth the $400 in my opinion.

 

Some of you may not agree with this but I come from the DSM world and it is common to just plug up the port on the turbo inlet altogether and run a straight up piece of rubber hose from the drivers side of the valve cover directly to the ground, lol. All vapors and blow-by hit the asphalt. I ran my TSi like this for 15 years with ZERO crud in my fmic and my intake and valves stayed clean to boot (of course not D.I.) but without a OCC at all.

 

Glad you brought this up. I was discussing this with a couple of friends yesterday and we think this would work with the mini's. But I am by no means a mechanic. I know enough to get me in trouble .

 

A High School friend of mine has an '09 MCS that he autocrosses. After ~60k miles, his carbon build-up was rather mild (worst valve was a grade 3).

His father has less than a 5 mile commute and rarely gets his engine up to temperature - at least, not for very long. His MCS had terrible carbon build-up after just 30k miles.


So it would seem than an occasional Italian tune-up just might be the right prescription for the N14s out there

 

Here is a link for Top Tier Gasoline Retailers. There is also a lot of information about engine deposits, gasoline detergent requirements, etc. Don't know for sure, but my guess is that this web site is sponsored by one or more gasoline detergent manufacturer/distributors.

http://www.toptiergas.com/retailers.html

 

Just did some digging… I had no idea "top tier" had meaning. I thought it just meant "buy name brand"!

This video from 76 appears to be more or less truthful http://www.76.com/OurGas.aspx

And here's a relevant excerpt from Wikipedia: http://en.wikipedia.org/wiki/Top_Tie...rgent_Gasoline


For what that's worth.

Note, though, that the article has been flagged by the Wikipedia community as being very ad-like. I checked the citations, and between the dates and titles, it's pretty clear that the coverage was the result of very good work by a PR firm in 07–08 and a bit more in 2010.

I'm not saying it's bad… sounds like Top Tier may be a good thing, since detergent quantities were cut prior to its introduction. But I can't help but think of the advice offered by the best Ducati mechanic I've ever met, Bruce Meyers: "Run the lowest octane you can without pinging. I'd run weasel **** if I could." The guy ran 87 octane in his race bikes with no trouble. On his advice, I ran 87 to 89 depending on temperatures and a decade in, my Ducati has no trouble, and far cleaner intake valves than other 996 Desmoquattro engines with a tenth the miles on them.

I can't help but take BMW's Top Tier destination with a grain of salt….

Wait! one more link: Automakers, Oil Industry in Fuel Fight:


If the API wasn't happy with it, then I am definitely happy with it. Top Tier for me
Okay, it's not actually as cut and dried as all that. I'm not quite sure what I believe.

 

Verrry interesting....great thread guys !

I've got a 2008 MCS with about 38000 miles, here in So Cal. I got a yellow CEL yesterday, took it into the dealer this AM (it's still under the extended warranty), and just got the call-back from the service writer, saying that the car needs a "carbon cleaning".

Once he said it's a "head-off" procedure I had a pretty good idea of what he was talking about but this thread confirmed it for me. He said they were going to request MINI NA to cover it for me, which is great news. Hopefully that happens... but he also said (when I asked him if this was a common thing for the MCS), that they normally recommend an injecter cleaning service at 35 K, but that it's not covered under the warranty (which is fine, but why didn't they tell me this the last time I'd brought it in, a few months back ... - I know, it's no doubt in the manual - I really need to be better about checking that but I've been lulled into the magical thinking that the car's maintenance reminder thingy would notify me of these things).

Soooo, they said they're going to need the car probably until Tuesday (it's Friday today), because it usually takes a few days for MNA to authorize this work under warranty. At least they're going to bat for me, and they're very good about providing free loaners.

Again, good information here, thanks and if anything else happens of interest on this, I'll report back.

 

It's not in the manual. The word "carbon" appears once in the whole 158 pages of it: page 39: "Exhaust gases contain carbon monoxide". Nothing to do with carbon build up. If you were "supposed" to do it at 35k, but they didn't tell you at your service at the time and it also was not documented in your owner's manual, that pretty clearly puts the onus on BMW. Glad the dealer is doing right by you!

(I have the owner's manual PDF on my phone, so I could search it. Boom baby!)

 

My first post on NA Motoring. Thanks to this site, I was aware of the problem. Check engine code at 48 K, dealer diagnosed carbon buildup. Walnut shell service- no cost, under warranty. Seems like an ongoing problem. I have driven my last 2 vehicles, both Audis, 250K and 275K with no such problems. Wondering if, for the first time, I will buy an extended warranty on this Mini. Love the car, but don't want unpleasant surprises. Have 1000 miles to make the decision. Comments please??

 

My dealer also diagnosed carbon buildup at 30k and serviced it under warranty. Soon after, I added a BSH OCC and Boost Tap and am also encountering slight oil consumption. At this time, I inquired about an extended warranty but was informed that carbon buildup was not covered (go figure ), so make sure you look into this.

 

09 JCW with 34,000 required cleanup with Walnut shell blast by the dealer. Solved my cold morning hesitation problem and likely improved performance / mileage. i also had the Timing Chain tensioner replaced prior to the carbon cleaning because that issue appeared first and masked the carbon issue. $619 was the bill for carbon cleaning, fortunately covered by CARMAX under their 60 day warranty. Lucky me.

 

So Craigdevdir, a Mini sles person coached me to never own a Mini without a original or extended warranty. i took his advice and am glad I did. Great car but too many issues. So far, I love the car enough to put up with all this stuff.

 

2008 MCS with 57k miles. Noticed initial starts in the morning were rough. Car would sputter out if I didn't rev the engine. Within a few weeks, the engine light was on. Took it to the dealer and they diagnosed carbon build up and needed to be blasted. Bought the car about a year ago from CarMax and paid extra for the Max Care Warranty, which surprising doesn't cover the $500, 3 hour procedure.

I work with a guy that has a 2009 with fewer miles that had the same issue a few months ago.

 

my car has been at the dealer since yesterday for carbon buildup. Still under warranty thankfully. I always use premium gas and do mostly highway driving, although admittedly it is a lot of stop and go since I live in Los Angeles...

 

2010 Clubman S - had to be decarbonized at 44,000kms under warranty... was idling rough and had stored misfire codes. The dealer removed the intake manifold and used a "carbon blaster" which I assume is the walnut shells.

 

I was told the n18 does not have this issue, Is this true? Thats what the dealer told me.

 

Please read post #276 from this link about carbon build up in a N18 engine. https://www.northamericanmotoring.co...11-mcs-12.html

 

My 2008 Clubman S , purchased in March 2008, had the engine check light go on at 17,988 miles in Nov. 2010. The dealer removed the manifold and did the manual clean up of the intake ports under warranty.
The car is driven largely in a stop and go, up and down hill area (San Francisco). We take some longer rides and trips but do mostly city driving.
Although oil is changed at 7 or 8k miles and Chevron or Shell gas is used, that apparently did not prevent the build up.
Currently at about 36,000 miles and engine seems OK. I do some blasting for a bit on the highway when I can. That may be helping.

I have accepted the carbon problem as a given with my car. I expect to be shopping for a clean up some time in the future.

 

2007 Cooper S- had carbon build up removal at 15k miles (2010) and now again at 28k (2012). Back in 2010 the dealership said it was a known issue with Minis and they had engineers from Germany over looking into the problem. Now they tell me it's because of bad gas. I only fill up at top tier staitions. Over this car.... as this is only part of the problems I have had with it.

 

It is not caused by the kind of gas you use. It is caused by oil mist from the Positive Crankcase Ventilation system that burns on the backs of the intake valves and slowly builds up until the ports are restricted. Our MINIs have direct fuel injection, in which the fuel is injected directly into the cylinder, so the fuel does not have an opportunity to wash the oil off of the intake valves as it does with more conventional port fuel injection.

2011 and newer MINI's with the N18 engine have a modified head and different valve timing, I haven't read of the newer engines having the carbon build up problem, maybe it is too soon to tell, but they may have solved the problem.

The addition of an oil catch can to the PCV system can help to slow the build up of carbon on the intake valves.

Dave

 

My wife just took her 2012 Coupe to the dealership with a check engine light.
They told her that they would need to do a preventative injectors and head clean recommended by Mini to prevent carbon build up and had here sign a work order and the cost would be $390.

I got involved after the work had started and said that this was ridiculous as we have had 3 mini's and BMWs and never had to do this.
The technician on the phone told me it was an issue with these engines but as it was preventative was not covered.

Outrageous

 

While not environmentally friendly that is the way my 68 Barracuda has always been. It has little breather filters that look like mushrooms stuffed with fiberglass that are installed in the valve covers. They have to be replaced relatively frequently because they build up oil and it starts to drip. The added problem caused by inadequate crank case vacuum is that the blow by gasses and moisture build up in the engine. Did you ever check the oil on an older car and see that grey sluggy stuff? On the Barracuda the driving to oil changes ratio is low enough that it isn't an issue.

Possibly combining the catch can with a filter similar to the breather filters might help. The catch can probably doesn't do much for the vapors but under hard driving or hilly conditions it should catch oil that "splashes" into the system.

If you want to feel a little better go on over the the M5 board and see what the dealers are charging them to do carbon clean ups

 

what did they really do that would really prevent this from happening? did they basically just do a preemptive cleaning and charge you for it??

 

58xxx and was advised to get the Walnut Cleaning for $700.00 Going to try to manually clean what I can :/

 

You were conned by the service guy.