My 2000 C280, 60m, is probably overdue for a plug change. Is this procedure pretty routine save for the cost of 12 plugs? Also I been reading that there is a potential of frozen plugs with this engine and that anti-seize is recommended with a change. Is it ever appropriate to spray a penetrating fluid like WD40 or Liquid Wrench down in the spark plug bore before trying to break them loose?

Thanks,

glenmore
2000 C280
1991 300CE
1990 LS400

Use of a spray won't accomplish any thing. Getting off the wire connectors might be the most difficult!
Just go easy & deliberate.

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I have had problems in the past with spark plugs seized in the aluminum heads of vw's. I found that squirting some 'tap magic' tapping fluid around the plug will prevent the galling that strips out the threads. If the plug turns hard after it is broken loose, just squirt some tap magic and work the plug. Sometimes you can only turn the plug a fraction of a turn but keep working it back and forth and the fluid penetrates and then the plug will come out cleanly. I have yet to have this method fail me. Penetrating oil may also work but I will continue to use what I know from experience will work.
I chase the threads before installing plugs if they did not remove easily and I use anti-sieze on the threads.

Well no walk in the park but certainly doable for the DIYer. Took me 4-5 hours with a lot of time wasted just trying to get the wires back on. No trouble breaking the plugs loose, they were not on tight at all. On the passengers side, working from front to back, it went quickly. The drivers side is tight. Removing the center coil first finally moved the repair along. It seemed I spent an inordinate amount of time just getting the wires back on. You'll need a nice assortment of short extensions, the more varied, the better. The hard part is pulling the wires. I used several tools, sparkplug wire puller by Lisle, pry bars, long screwdrivers and a 17mm wrench, the thinner the better. I think the plugs are original to the car, model year 2000 with 60m. All the threads of the plugs were covered with brown black sticky varnish. The plug closet to the driver was clearly fouled and the other one on the same coil was slightly fouled. The rest of the plugs looked OK except for the stuff on the threads. Is this normal? I also just changed the plugs on my 300CE after about 4 years. The threads were nice and clean. What could have caused the fouling of the 2 plugs? They were both on the same coil. Faltering coil? Or is it simply the plugs being too old? Attached is a photo. The two on the right were the worst.

glenmore
2000 C2809
1991 300CE
1990 LS400

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