Roadster Sparkplug Fitting
The Roadster engine is almost identical to the Fortwo engine so the sparkplug changing guide is the same. What does differ is the access. Here is a quick way.
Removing the rear panels of a Fortwo is easy, removing the rear panels of a Roadster is a bit more of a pain so here is a far easier way of doing it. Thanks to Ferrina for the information.
What Sparkplugs Do I Need?
For the Roadster there are 2 options for standard plugs
6x NGK R LKR8A (OEM fitted).
6x NGK R LKR8AP (Platinum) - thanks Neil.
The upper set of 3 spark plugs are the same as before so take a look here.
Lower Plugs - Hidden Access
The lower set are the same as before but we are going to cheat on the access.
Run a pencil line around the outside edge of the number plate on the right side as you look at it.
Then remove rear number plate.
Using an electric drill and a 50mm hole cutter (I used one which is used for making stair banister post holes), carefully cut out three holes 10mm inside the pencil line as shown below.
If you want to be more accurate and you are using a 50mm hole cutter...
...measure up 35mm from the pencil line.
The hole centres from the right hand line are...
50mm, 110mm, 170mm.
You will see from the next picture that the tolerances aren't particularly tight
so don't be too worried about getting this spot on.
With an HT lead remover, a long extension piece, rachet and a universal joint, the spark
plugs can be removed with very little hassle and replaced with the panel still in situ.
The smart's own HT lead remover is rubbish. The better the quality HT lead remover
and spark plug socket with a universal joint, the easier this job will be.
Apart from the obvious time it saves, doing this mod has a few extra bonuses. You can:
inspect the turbo studs
view the upstream lambda sensor
inspect the TIK pipe
check the turbo
view the back section of the engine
Ferrina rightly points out that if the 50mm holes continued all the way along, top and bottom,
the number plate could be slightly spaced out from holed panel. This would act as a vent and would allow hot air from the engine and the exhaust to escape the engine bay.
Thanks again to Ferrina (Neil) for the information.