Hi,
Got my new Super S Mini in 2007. Now has 116,000 miles. ALMOST considered trading it in because of long-time-to-find cause of Check Engine Light. Fault code P115C found by Meineke and was getting ready to replace O2 Sensors. Another mechanic showed same code but for Mass Air Flow Sensor Plausibility fault. Mini dealer gave same code, but they had to dig deep to find the real cause. They had to do a SMOKE test to find cause of air leak. Cost? $500. Air leak traced to Valve cover. A 2nd code indicated CARBON buildup. How come Carbon buildup when I use Chevron Supreme? Is it really that I'm doing short trips a lot? Moral of the story? When the Mini Dealer and Meineke recommended replacing the valve cover about 2 years ago I should have done it. Check Engine light coming on is a pain to find cause! And also, to do some kind of cleaning of the engine from time to time. Mini Dealer wants 750.00 to sand blast the engine with walnut shells to clean it out. Not so fast there! IS THERE A CHEAPER WAY TO CLEAN THE CARBON?

 

I've run by a number of threads here that describe this issue on second gen MINIs. It's not a gas or driving caused build-up, but a result of the engine design using direct injection. Do a search for "direct injection carbon build-up" and you'll see a flood of results with many different cars, not just the MINI.

I think a lot of folks get oil catch cans to reduce the carbon build-up. Search around - I'm sure there are multiple threads on it here. Either way, you will have to get valves cleaned one way or another first.

 

Search Seafoam for cleaning carbon cleanup.

 

If you let it go too far the build up can eventualy result in serious engine damage so you do need to get them cleaned.
Carbon build up is just a part of owning these "high performance" engines and if you want to play eventualy your'e going to have to pay.

 

Thank you. Very interesting. So, I just relax and not be concerned about driving it to the store... Yes, getting the valves cleaned without it being a costly affair, is my next step. But I'm wondering now if the valves are really bad since there are NO symptoms of carbon buildup such as hesitation, backfiring, loss of power, etc.? And if they're not really bad then I can then just use something like Seafoam to clean the valves. What do you think?

 

Thank you. News to me. I will use Seafoam, but need to find out exactly how dirty the intake valves are... not sure how to go about this. If they are very gunked up then from what I've read Seafoam will not work, and best in this case to sandblast with walnut shells. Hope this latter is not the case. My private, highly ethical mechanic may be able to ascertain the level of gunk... we'll seek.

 

Thanks for the warning. I will not take it lightly.

 

Let us know where you are and maybe someone can direct to an independent MINI shop and save you some money.

If you are in the Philly area look up helix13.com. If you are in California area check out ltmotorwerks.com. They are a BMW shop, but they do Walnut Shell blasting. Both are way cheaper then dealer.

If you want to know what your valves look like it isn't that hard to remove the intake and use a mirror and a flashlight to see the current condition. (Depends on how handy you are. )

Others have either bought or built their own walnut shell blasting equipment.

Valve cover is an easy change. It is like 13 bolts. Will save you some $$ if you DIY.

I just had Helix clean mine at 100k miles. Here are a couple of pictures before and after. I was not having any performance issues. Just wanted to reset the clock at 100k miles. https://www.northamericanmotoring.co...83-post10.html

 

Seafoam might work as a preventative, but only when it is sprayed directly into the intake manifold. Search "Seafoam" to see "how to" posts.

The only way to remove built up carbon on the intake valves is to remove the intake manifold and mechanically clean the backs of the valves either with walnut shell media blasting or with wire brushes and a carbon dissolving chemical, like Seafoam.

Dave

 

You are indeed a 'gifted mechanic'. I will pass the wire brushes and Seafoam method to my 'backyard mechanic'. Yea. I think this will save some bucks! Thanks so much!

 

Thank you! I'm getting so much out of this connection with Mini Cooper folk. For one thing, I will not give up my Mini now!

Can you imagine the dealership wanted 1,200 to replace the valve cover, and when you look online, as my backyard mechanic did, it takes 1.2 hrs of labor.I got the whole thing done for 1/3 rd the price which includes the factory valve cover!

I'm going to take the other fellow's advise and have my mechanic use a wire brush and Seafoam. Will follow your advise regarding taking a look inside. This is all so helpful! Incidentally, your valves look brand new!!