While changing the sparkplugs on my wife’s roadster, I discovered a minor valve cover leak.
Mercedes books about 8 hours* for a sparkplug change on the car, which has the M275 V-12 engine with 2 plugs per cylinder. Yes, that’s a total of 24 iridium plugs. since the coils have to come out to get the valve covers off, better to clean up the leak while doing the plugs.
The car was dealer serviced. 10,000 mile intervals. Mobil 1 0W40 as far as I can tell. But it was many years between each change. 52,000 total miles. Here’s how it looked.
Passenger side:
View attachment 128297
Driver side:
View attachment 128298
I used new insulator boots for each plug, and reused the coils, which are notorious for short lives. I’m hoping that the new plugs keep those coils happy.
I‘m pleased with how the engine looks. I took a look down each cylinder with my scope. Cylinder walls look perfect. Tiny bit of carbon above the ring travel. Tried to take pictures of them as well, but I clearly didn’t remember the scope directions.
The engine as it sits with the beauty covers off and all the parts in place.
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*A lot of intake and other parts have to come off to get the coils out. Each coil is about two feet long, and fires 12 plugs.