Sunday, April 10, 2011

R56 MINI Cooper S Spark Plug Change DIY

Note: A PDF version is available.

Another DIY for me. This time a relatively simple job – changing the spark plugs on my R56 MCS. The spark plugs on an MCS should be changed every 60k miles (so I am overdue by quite a bit). On a MC the interval is 100k miles. With the way life has panned out for me, I don’t think I’ve ever changed spark plugs on a vehicle, so this was something new for me.


First up was to find the proper spark plugs. I was fortunate to find a couple threads over at Motoring Alliance on the subject. First up was a post – A Basic Guide to Spark Plugs – which helped me get up to speed. The second was a thread about what spark plugs people were using in their MINIs. I’ve gathered at this point that there are basically 3 choices (4 I suppose if you get them from the dealership) – Brisk, NGK, and Beru. NGK is what comes installed in the MINI (at least in mine they were). However, I decided I wanted to maybe notch things up just a bit compared stock, so I ordered some of the Brisk plugs - MR12YS – from Alta Performance (a Google shopping search will yield some other sources, but I couldn’t find anything cheaper than Alta, although per piece I could if I ordered six at one time as packaged for a Mitsubishi Evo 10).


Before you get started though, you will need one other special item. The stock spark plugs require a 14mm 12 point spark plug socket. This is probably not something you are going to find at the local parts store. Fortunately, BMWs require this as well, so it was not hard to find an Assenmacher (ASSSP1412) 12 Point Thin Walled 14mm Spark Plug Socket on And kudos to Tooltopia who had it to me in only about 3 days.

My final pre-install step was to gap the spark plugs (may not be necessary if you go with NGK or Beru). The Brisk plugs come with a huge gap and I had to get them down to .018”. That took some patience to do it without messing up the tip.

The installation itself took maybe 15 minutes. One tip I picked up was to remove and install one plug at a time so as not to get wires crossed up (which may not really be possible with a MINI, but better safe than sorry). So I worked right to left looking at my engine from the front of the car.

The first step is to remove the ignition coils. These are the four connectors you see along the top of the motor. There is no trick to getting them off – you just pull them straight up. Go ahead and really pull up on them!



Once you have them loose, pull them on up and out. They are about six inches long. The bottom part is rubber, so it is flexible if you are worried as you pull them out – with the wires connected, the angle gets a little sharp. Looking down, you can see the spark plug down at the bottom.



Put the socket on an extension and unscrew the spark plug. Then screw a new spark plug in. For an MCS, the spark plugs should be torqued to 14.5 lb-ft.


One issue I did run into is that the socket had such a strong grip on the spark plug, that I could not pull it back out without it coming off the extension bar. That was solved by using some electrical tape to hold the socket and the extension together:


I did use some tape and marked each of the spark plugs as I took them out (using the right to left numbers). Since the plugs I’m using required me to gap them myself and are a little different from stock in the material they use, I wanted to be sure I could revert things if something doesn’t work out. I know the plugs I’m taking out work, so if needed I can re-install them. It may not matter, but I’d want to put them back in to the same place they came out of.


Finally, below is a pic showing one of the plugs taken out and the Brisk plug next to it. The plugs that came out looked to be in pretty good condition to me. Obviously used, but no unusual discoloration.


Upon completion, I did test things out and started up the MINI. I’m glad to report that I did have fire with the successful start! And a quick drive down the road seemed to be a smooth run. I’ll keep an eye on how the MINI runs the next couple weeks to see if I notice any stumbling, misses, or major changes in fuel mileage.

The spark plug change itself is pretty easy. Hope the tips in this DIY are helpful!

Enjoy motoring!

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